标准编号:	GB/T 1094.1-2013/XG1-2018
中文名称:	电力变压器 第1部分：总则，含国家标准第1号修改单
英文名称:	Power transformers―Part 1:General, includes Amendment 1
中标分类:	K41    变压器
行业分类:	GB    国家标准
ICS分类:	29.180 29.180    变压器、电抗器 29.180
发布机构:	中华人民共和国国家质量监督检验检疫总局 中国国家标准化管理委员会
发布日期:	2013-12-17
实施日期:	2018-2-1
标准状态:	现行
替代旧标准:	GB 1094.1-2013 电力变压器 第1部分：总则 GB/T 1094.1-2013 电力变压器 第1部分：总则
翻译语言:	英文
文件格式:	PDF
中文字符数:	50000 字
翻译价格(元):	2300.00 元
交付时间:	付款后 1 个工作日

NATIONAL STANDARD

OF THE PEOPLE'S REPUBLIC OF CHINA

中华人民共和国国家标准

GB 1094.1-2013

Power Transformers - Part 1: General

电力变压器 第1部分: 总则



1 Scope



This part of GB 1094 applies to three-phase and single-phase power transformers (including auto-transformers) with the exception of certain categories of small and special transformers such as:

——single-phase transformers with rated power less than 1 kVA and three-phase transformers less than 5 kVA;

——transformers, which have no windings with rated voltage higher than 1000 V;

——instrument transformers;

——traction transformers mounted on rolling stock;

——starting transformers;

——testing transformers;

——welding transformers;

——explosion-proof and mining transformers;

——transformers for deep water (submerged) applications.

When some standards do not exist for such categories of transformers (in particular transformer having no winding exceeding 1000V for industrial applications), this part may still be applicable either as a whole or in part.

This part does not address the requirements that would make a transformer suitable for mounting in a position accessible to the general public.

For those categories of power transformers and reactors which have their own standards, this part is applicable only to the extent in which it is specifically called up by cross-reference in the other standard. Such standards exist for:

——reactors (GB/T 1094.6);

——dry-type transformers (GB 1094.11);

——self-protected transformers (IEC 60076-13);

——gas-filled power transformers (IEC 60076-15);

——transformers for wind turbine applications (GB 1094.16);

——traction transformers and traction reactors (GB/T 25120);

——converter transformers for industrial applications (GB/T 18494.1);

——converter transformers for HVDC applications (GB/T 18494.2).

At several places in this part it is specified or recommended that an 'agreement' should be reached concerning alternative or additional technical solutions or procedures. Such agreement is made between the manufacturer and the purchaser. The matters should preferably be raised at an early stage and the agreements included in the contract specification.



2 Normative References



The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

GB 1094.2 Power Transformers Part 2: Temperature Rise for Liquid-immersed Transformers (GB 1094.2-2013, IEC 60076 - 2: 2011, MOD)

GB 1094.3 Power transformers - Part 3: Insulation Levels, Dielectric Tests and External Clearances in Air (GB 1094.3-2003, IEC 60076-3: 2000, MOD)

GB 1094.5 Power Transformers - Part 5: Ability to Withstand Short Circuit (GB 1094.5-2008, IEC 60076-5: 2006, MOD)

GB/T 1094.10 Power Transformers - Part 10: Determination of Sound Levels (GB/T 1094.10-2003, IEC 60076-10: 2001, MOD)

GB 1094.11 Power Transformers - Part 11: Dry-type Transformers (GB 1094.11-2007, IEC 60076-11: 2004, MOD)

GB/T 2521 Cold-rolled Grain-oriented and Non-oriented Magnetic steel Strip (Sheet) (GB/T 2521-2008, IEC 60404-8-7: 1998 and IEC60404-8-4: 1998, MOD)

GB 2536 Fluids for Electrotechnical Applications - Unused Mineral Insulating oils for Transformers and Switchgear(GB 2536-2011, IEC 60296: 2003, MOD)

GB/T 2900.15 Electrotechnical Terminology - Transformer, Instrument Transformer, Voltage Regulator and Reactor (GB/T 2900.15-1997, neq. IEC 60050-421: 1990 and IEC 60050-321: 1986)

GB/T 4109 Insulated Bushings for Alternating Voltages above 1 000V (GB/T 4109-2008, IEC 60137: 2008, MOD)

GB/T 4798.4 Environmental Conditions Existing in the Application of Electric and Electronic Products - Part 4: Stationary Use at Non-weather-protected Locations (GB/T 4798.4-2007, IEC 60721-3-4: 1995, MOD)

GB 10230.1 Tap-changers - Part 1: Performance Requirements and Test Methods (GB 10230.1-2007, IEC 60214-1: 2003, MOD)

GB/T 19001 Requirements for Quality Management System (GB/T 19001-2008, ISO 9001: 2008, IDT)



3 Terms and Definitions



For the purposes of this document, the terms and definitions specified in GB/T 2900.15 and the following ones apply. Some are listed more than once and some are changed.

3.1 General

3.1.1

Power transformer

A static piece of apparatus with two or more windings which, by electromagnetic induction, transforms a system of alternating voltage and current into another system of voltage and current usually of different values and at the same frequency for the purpose of transmitting electrical power.

Note: GB/T 2900.15-1997, 3.1.1, modified.

3.1.2

Auto-transformer

A transformer in which at least two windings have a common part.

[GB/T 2900.15-1997, 3.1.15]

Note: Where there is a need to express that a transformer is not auto-connected, use is made of terms such as separate winding transformer, or double-wound transformer.

3.1.3

Series transformer

A transformer, other than an autotransformer, of which one winding is intended to be connected in series with a circuit in order to alter its voltage and/or shift its phase. The other winding is an energizing winding.

Note 1: GB/T 2900.15-1997, 3.1.8, modified.

Note 2: Series transformers were called booster transformers in earlier editions of this part.

3.1.4

Liquid-immersed type transformer

A transformer in which the core and windings are immersed in liquid.

[GB/T 2900.15-1997, 3.1.4]

3.1.5

Dry-type transformer

A transformer in which the core and windings are not immersed in an insulating liquid

[GB/T 2900.15-1997, 3.1.5]

3.1.6

Liquid preservation system

System in a liquid-filled transformer by which the thermal expansion of the liquid is accommodated.

Note: Contact between the liquid and external air may sometimes be diminished or prevented.

3.1.7

Specified value

The value specified by the purchaser at the time of order.

3.1.8

Design value

The expected value given by the number of turns in the design in the case of turns ratio or calculated from the design in the case of impedance, no-load current or other parameters.

3.1.9

Highest voltage for equipment applicable to a transformer winding

Um

The highest r.m.s. phase-to-phase voltage in a three-phase system.

[GB 1094.3-2003, 3.1]

3.2 Terminals and neutral point

3.2.1

Terminal

A conducting element intended for connecting a winding to external conductors.

3.2.2

Line terminal

A terminal intended for connection to a line conductor of a network.

[GB/T 2900.15-1997, 5.5.1]

3.2.3

Neutral terminal

Neutral terminal includes:

a) for three-phase transformers and three-phase banks of single-phase transformers: the terminal or terminals connected to the common point (the neutral point) of a star- connected or zigzag connected winding

b) for single-phase transformers: the terminal intended for connection to a neutral point of a network.

Note: GB/T 2900.15-1997, 5.5.2, modified.

3.2.4

Neutral point

The point of a symmetrical system of voltages which is normally at zero potential.

3.2.5

Corresponding terminal

Terminals of different windings of a transformer, marked with the same letter or corresponding symbol.

[GB/T 2900.15-1997, 2.1.28]

3.3 Windings

3.3.1

Winding

The assembly of turns forming an electrical circuit associated with one of the voltages assigned to the transformer

Note 1: GB/T 2900.15-1997, 4.3.1, modified.

Note 2: For a three-phase transformer, the 'winding' is the combination of the phase windings (see 3.3.3).

3.3.2

Tapped winding

A winding in which the effective number of turns can be changed in steps.

3.3.3

Phase winding

The assembly of turns forming one phase of a three-phase winding.

Note 1: GB/T 2900.15-1997, 4.3.16, modified.

Note 2: The term 'phase winding' shall not be used for identifying the assembly of all coils on a specific leg.

3.3.4

High-voltage winding; HV winding

The winding having the highest rated voltage

[GB/T 2900.15-1997, 4.3.2]

3.3.5

Low-voltage winding; LV winding1

The winding having the lowest rated voltage.

[GB/T 2900.15-1997, 4.3.3]

Note: For a series transformer, the winding having the lower rated voltage may be that having the higher insulation level.

3.3.6

Intermediate-voltage winding1

A winding of a multi-winding transformer having a rated voltage intermediate between the highest and lowest winding rated voltages.

[GB/T 2900.15-1997, 4.3.4]

3.3.7

Auxiliary winding

A winding intended only for a small load compared with the rated power of the transformer.

[GB/T 2900.15-1997, 4.3.11]

3.3.8

Stabilizing winding

A supplementary delta-connected winding provided in a star-star-connected or star-zigzag- connected transformer to decrease its zero-sequence impedance, see 3.7.3

Note 1: GB/T 2900.15-1997, 4.3.12, modified.

Note 2: A winding is referred to as a stabilizing winding only if it is not intended for three-phase connection to an external circuit.

3.3.9

Common winding

The common part of the windings of an auto-transformer.

[GB/T 2900.15-1997, 4.3.13]

3.3.10

Series winding

The part of the winding of an auto-transformer or the winding of a series transformer which is intended to be connected in series with a circuit.

Note: GB/T 2900.15-1997, 4.3.14, modified.

3.3.11

Energizing winding

The winding of a series transformer (or series transformer) which is intended to supply power to the series winding.

Note: GB/T 2900.15-1997, 4.3.15, modified.

3.3.12

Auto-connected windings

The series and common windings of an auto-transformer.

3.4 Rating

3.4.1

Rating

Those numerical values assigned to the quantities which define the operation of the transformer in the conditions specified in this part and on which the manufacturer's guarantees and the tests are based.

3.4.2

Rated quantities

Quantities (voltage, current, etc.), the numerical values of which define the rating.

Note 1: For transformers having tappings, rated quantities are related to the principal tapping (see 3.5.2), unless otherwise specified. Corresponding quantities with analogous meaning, related to other specific tappings, are called tapping quantities (see 3.5.9).

Note 2: Voltages and currents are always expressed by their r.m.s. values, unless otherwise specified.

3.4.3

Rated voltage of a winding

Ur

The voltage assigned to be applied, or developed at no-load, between the terminals of an untapped winding, or of a tapped winding connected on the principal tapping (see 3.5.2) , for a three-phase winding it is the voltage between line terminals.

Note 1: GB/T 2900.15-1997, 2.1.4, modified.

Note 2: The rated voltages of all windings appear simultaneously at no-load when the voltage applied to one of them has its rated value.

Note 3: For single-phase transformers intended to be connected in star to form a three-phase bank or to be connected between the line and the neutral of a three phase system, the rated voltage is indicated as the phase-to-phase voltage, divided by . Such as:

kV

Note 4: For single phase transformers intended to be connected between phases of a network, the rated voltage is indicated as the phase-to-phase voltage.

Note 5: For the series winding of a three-phase series transformer, which is designed as an open winding (see 3.10.5), the rated voltage is indicated as if the windings were connected in star.

3.4.4

Rated voltage ratio

The ratio of the rated voltage of a winding to the rated voltage of another winding associated with a lower or equal rated voltage

Note: GB/T 2900.15-1997, 2.1.5, modified.

3.4.5

Rated frequency

fr

The frequency at which the transformer is designed to operate.

Note: GB/T 2900.15-1997, 2.1.6, modified.

3.4.6

Rated power

Sr

Conventional value of apparent power assigned to a winding which, together with the rated voltage of the winding, determines its rated current.

Note: Both windings of a two-winding transformer have the same rated power which by definition is the rate d power of the whole transformer.

3.4.7

Rated current

Ir

The current flowing through a line terminal of a winding which is derived from rated power Sr and rated voltage Ur for the winding.

Note 1: GB/T 2900.15-1997, 2.1.7, modified.

Note 2: For a three-phase winding the rated current is given by:



Note 3: For single-phase transformer windings intended to be connected in delta to form a three-phase bank, the rated current is indicated as line current divided by :



Note 4: For a single phase transformer not intended to be connected to form a three phase bank, the rated current is:



Note 5: The rated current of the open windings is the rated power divided by the number of phases and by the rated voltage of the open winding:



Where,

n——the number of phase.

3.5 Tappings

3.5.1

Tapping

In a transformer having a tapped winding, a specific connection of that winding, representing a definite effective number of turns in the tapped winding and, consequently, a definite turns ratio between this winding and any other winding with a fixed number of turns.

Note: One of the tappings is the principal tapping, and other tappings are described in relation to the principal tapping by their respective tapping factors. See definitions of these terms below.

3.5.2

Principal tapping

The tapping to which the rated quantities are related.

[GB/T 2900.15-1997, 2.1.12]

3.5.3

Tapping factor (corresponding to a given tapping)

The ratio:

Ud/Ur (tapping factor) or 100Ud/Ur (tapping factor expressed as a percentage).

Where,

Ur——the rated voltage of the winding (see 3.4.3);

Ud——the voltage which would be developed at no-load at the terminals of the winding, at the tapping concerned, by applying rated voltage to an untapped winding

Note 1: For series transformers, the tapping factor is the ratio of the voltage of the series winding corresponding to a given tapping to Ur.

Note 2: GB/T 2900.15-1997, 2.1.13, modified.

3.5.4

Plus tapping

A tapping whose tapping factor is higher than 1.

[GB/T 2900.15-1997, 2.1.14]

3.5.5

Minus tapping

a tapping whose tapping factor is lower than 1.

[GB/T 2900.15-1997, 2.1.15]

3.5.6

Tapping step

The difference between the tapping factors, expressed as a percentage, of two adjacent tappings.

[GB/T 2900.15-1997, 2.1.16]

3.5.7

Tapping range

The variation range of the tapping factor, expressed as a percentage, compared with the value 100.

Note: If this factor ranges from 100 + a to 100 – b, the tapping range is said to be: +a %, –b % or ±a %, if a = b.

[GB/T 2900.15-1997, 2.1.17]

3.5.8

Tapping voltage ratio (of a pair of windings)

The ratio which is equal to the rated voltage ratio:

Multiplied by the tapping factor of the tapped winding if this is the high-voltage winding;

Divided by the tapping factor of the tapped winding if this is the low-voltage winding.

[GB/T 2900.15-1997, 2.1.18]

Note: While the rated voltage ratio is, by definition, at least equal to 1, the tapping voltage ratio can be lower than 1 for certain tappings when the rated voltage ratio is close to 1.

3.5.9

Tapping quantities

Those quantities the numerical values of which define the duty of a particular tapping (other than the principal tapping).

Note 1: Tapping quantities exist for any winding in the transformer, not only for the tapped winding (see 6.2 and 6.3).

The tapping quantities are:

——tapping voltage (analogous to rated voltage, 3.4.3);

——tapping power (analogous to rated power, 3.4.6);

——tapping current (analogous to rated current, 3.4.7).

Note 2: GB/T 2900.15-1997, 2.1.20, modified.

3.5.10

Full-power tapping

A tapping whose tapping power is equal to the rated power.

[GB/T 2900.15-1997, 2.1.24]

3.5.11

Reduced-power tapping

A tapping whose tapping power is lower than the rated power.

[GB/T 2900.15-1997, 2.1.25]

3.5.12

On-load tap-changer; OLTC

A device for changing the tapping connections of a winding, suitable for operation while the transformer is energized or on load.

[GB/T 2900.15-1997, 5.6.1]

3.5.13

De-energized tap-changer; DETC

A device for changing the tapping connections of a winding, suitable for operation only while the transformer is de-energized (isolated from the system).

Note: GB/T 2900.15-1997, 5.6.2, modified.

3.5.14

Maximum allowable tapping service voltage

The voltage at rated frequency a transformer is designed to withstand continuously without damage at any particular tap position at the relevant tapping power

Note 1: This voltage is limited by Um.

Note 2: This voltage will normally be limited to 105 % of the rated tapping voltage unless a higher voltage is required by the purchaser’s specification of the tapping (see 6.4) either explicitly or as a result of a specification according to 6.4.2.

3.6 Loss and no-load current

The values are related to the principal tapping, unless another tapping is specifically stated.

3.6.1

No-load loss

The active power absorbed when a rated voltage (tapping voltage) at a rated frequency is applied to the terminals of one of the windings, the other winding or windings being open- circuited.

Note: GB/T 2900.15-1997, 2.1.33, modified.

3.6.2

No-load current

The r.m.s. value of the current flowing through a line terminal of a winding when rated voltage (tapping voltage) is applied at a rated frequency to that winding, the other winding or windings being open-circuited.。

Note 1: For a three-phase transformer, the value is the arithmetic mean of the values of current in the three lines.

Note 2: The no-load current of a winding is often expressed as a percentage of the rated current of that winding. For a multi-winding transformer, this percentage is referred to the winding with the highest rated power.

Note 3: GB/T 2900.15-1997, 2.1.34, modified.

3.6.3

Load loss

The absorbed active power at a rated frequency and reference temperature (see 11.1), associated with a pair of windings when rated current (tapping current) is flowing through the line terminals of one of the windings, and the terminals of the other winding are short- circuited. Further windings, if existing, are open-circuited.

Note 1: For a two-winding transformer, there is only one winding combination and one value of load loss.

For a multi-winding transformer, there are several values of load loss corresponding to the different two-winding combinations (see Clause 7 of GB/T 13499-2002). A combined load loss figure for the complete transformer is referred to a specified winding load combination. In general, it is usually not accessible for direct measurement in testing.

Note 2: When the windings of the pair have different rated power values, the load loss is referred to rated current in the winding with the lower rated power and the reference power shall be mentioned.

Note 3: GB/T 2900.15-1997, 2.1.31, modified.

3.6.4

Total losses

The sum of the no-load loss and the load loss.

Note 1: The power consumption of the auxiliary plant is not included in the total losses and shall be stated separately.

Note 2: GB/T 2900.15-1997, 2.1.30, modified.

3.7 Short-circuit impedance and voltage drop

3.7.1

Short-circuit impedance of a pair of windings

The equivalent series impedance Z=R+jX(Ω) at rated frequency and reference temperature, across the terminals of one winding of a pair, when the terminals of the other winding are short-circuited and further windings, if existing, are open-circuited: for a three- phase transformer, the impedance is expressed as phase impedance (equivalent star connection).

Note 1: In a transformer having a tapped winding, the short-circuit impedance is referred to a particular tapping. Unless otherwise specified, the principal tapping applies.

Note 2: This quantity can be expressed in relative, dimensionless form, as a fraction z of the reference impedance Zref, of the same winding of the pair. In percentage notation:



Where,



Formula valid for both three-phase and single-phase transformers.

U——the voltage (rated voltage or tapping voltage) of the winding to which Z and Zref belong;

Sr——the reference value of rated power.

The relative value is also equal to the ratio between the applied voltage during a short-circuit measurement which causes the relevant rated current (or tapping current) to flow, and rated voltage (or tapping voltage). This applied voltage is referred to as the short-circuit voltage (see GB/T 2900.15-1997, 2.1.37) of the pair of windings. It is normally expressed as a percentage.

Note 3: GB/T 2900.15-1997, 2.1.37, modified.

3.7.2

Voltage drop of rise for a specified load condition

The arithmetic difference between the no-load voltage of a winding and the voltage developed at the terminals of the same winding at a specified load and power factor, the voltage supplied to (one of) the other winding(s) being equal to:

——its rated value if the transformer is connected on the principal tapping (the no- load voltage of the winding is then equal to its rated value);

—— the tapping voltage if the transformer is connected on another tapping.

This difference is generally expressed as a percentage of the no- load voltage of the winding.

Note: For multi-winding transformers, the voltage drop or rise depends not only on the load and power factor of the winding itself, but also on the load and power factor of the other windings (see GB/T 13499).

[GB/T 2900.15-1997, 2.1.40]

3.7.3

Zero-sequence impedance (of a three-phase winding)

The impedance, expressed in ohms per phase at rated frequency, between the line terminals of a three-phase star-connected or zigzag-connected winding, connected together, and its neutral terminal.

Note 1: The zero-sequence impedance may have several values because it depends on how the terminals of the other winding or windings are connected and loaded.

Note 2: The zero-sequence impedance may be dependent on the value of the current and the temperature, particularly in transformers without any delta-connected winding.

Note 3: The zero-sequence impedance may also be expressed as a relative value in the same way as the (positive sequence) short-circuit impedance (see 3.7.1).

Note 4: GB/T 2900.15-1997, 2.1.41, modified.

3.8 Temperature rise

Temperature rise

The difference between the temperature of the part under consideration and the temperature of the external cooling medium (see GB 1094.2).

Note: GB/T 2900.15-1997, 2.1.46, modified.

3.9 Insulation

For terms and definitions relating to insulation, see GB 1094.3.

3.10 Connections

3.10.1

Star connection

The winding connection so arranged that each of the phase windings of a three-phase transformer, or of each of the windings for the same rated voltage of single- phase transformers associated in a three-phase bank, is connected to a common point (the neutral point) and the other end to its appropriate line terminal

Note 1: GB/T 2900.15-1997, 4.4.1, modified.

Note 2: Star connection is sometimes referred to as Y-connection.

3.10.2

Delta connection

The winding connection so arranged that the phase windings of a three- phase transformer, or the windings for the same rated voltage of single-phase transformers associated in a three- phase bank, are connected in series to form a closed circuit.

Note 1: GB/T 2900.15-1997, 4.4.2, modified.

Note 2: Delta connection is sometimes referred to as D-connection.

3.10.3

Open-delta connection

The winding connection in which the phase windings of a three-phase transformer, or the windings for the same rated voltage of single-phase transformers associated in a three-phase bank, are connected in series without closing one corner of the delta.

[GB/T 2900.15-1997, 4.4.4]

3.10.4

Zigzag connection

A winding connection consisting of two winding sections, the first section connected in star, the second connected in series between the first section and the line terminals: the two sections are arranged so that each phase of the second section is wound on a different limb of the transformer to the part of the first section to which it is connected.

Note 1: See Annex C for cases where the winding sections have equal voltages.

Note 2: zigzag connection is sometimes referred to as Z-connection.

3.10.5

Open windings

The phase windings of a three-phase transformer which are not interconnected within the transformer.

Note: GB/T 2900.15-1997, 4.4.5, modified.

3.10.6

Phase displacement (of a three-phase winding)

The angular difference between the phasors representing the voltages between the neutral point (real or imaginary) and the corresponding terminals of two windings, a positive- sequence voltage system being applied to the high-voltage terminals, following each other in alphabetical sequence if they are lettered, or in numerical sequence if they are numbered: the phasors are assumed to rotate in a counter-clockwise sense

Note 1: GB/T 2900.15-1997, 2.1.27, modified.

Note 2: See Clause 7 and Annex C.

Note 3: The high-voltage winding phasor is taken as reference, and the displacement for any other winding is conventionally expressed by the 'clock notation', that is, the hour indicated by the winding phasor when the H.V. winding phasor is at 12 o'clock (rising numbers indicate increasing phase lag).

3.10.7

Connection symbol

A conventional notation indicating the connections of the high-voltage, intermediate-voltage (if any), and low-voltage windings and their relative phase displacement(s) expressed as a combination of letters and clock-hour figure(s).

Note: GB/T 2900.15-1997, 2.1.26, modified.

3.11 Test classification

3.11.1

Routine test

A test to which each individual transformer is subjected

3.11.2

Type test

A test made on a transformer which is representative of other transformers, to demonstrate that these transformers comply with the specified requirements not covered by the routine tests: a transformer is considered to be representative of others if it is built to the same drawings using the same techniques and materials in the same factory.

Note 1: Design variations that are clearly irrelevant to a particular type test would not require that type test to be repeated.

Note 2: Design variations that cause a reduction in values and stresses relevant to a particular type test do not require a new type test if accepted by the purchaser and the manufacturer.

Note 3: For transformers below 20 MVA and Um≤72.5 kV, significant design variations may be acceptable if supported by demonstration of compliance with type test requirements.

3.11.3

Special test

A test other than a type test or a routine test, agreed by the manufacturer and the purchaser.

Note: Special tests can be carried out on one transformer or all transformers of a particular design, as specified by the purchaser in the enquiry and order for every special test.

3.12 Meteorological data with respect to cooling

3.12.1

Temperature of cooling medium (at any time)

The maximum temperature of the cooling medium measured over many years.

3.12.2

Monthly average temperature

Half the sum of the average of the daily maxima and the average of the daily minima during a particular month over many years.

3.12.3

Yearly average temperature

One-twelfth of the sum of the monthly average temperatures.

3.13 Other definitions

3.13.1

Load current

The r.m.s. value of the current in any winding under service conditions

3.13.2

Total harmonic content

The ratio of the effective value of all the harmonics to the effective value of the fundamental (E1, I1).

Total harmonic content:



Total harmonic content:



Where,

Ei——the r.m.s. value of voltage of the ith harmonic;

Ii——the r.m.s. value of current of the ith harmonic.

3.13.3

Even harmonic content

The ratio of effective value of all the even harmonics to the effective value of the fundamental (E1, I1)

Even harmonic content:



Even harmonic content:



Where,

E2i——the r.m.s. value of voltage of the 2ith harmonic;

I2i——the r.m.s. value of current of the 2ith harmonic.



4 Service Conditions



4.1 General

The service conditions set out in 4.2 represent the normal scope of operation of a transformer specified to this standard. For any unusual service conditions which require special consideration in the design of a transformer see 5.5. Such conditions include high altitude, extreme high or low external cooling medium temperature, tropical humidity, seismic activity, severe contamination, unusual voltage or load current wave shapes, high solar radiation and intermittent loading. They may also concern conditions for shipment, storage and installation, such as weight or space limitations (see Annex D).

Supplementary rules for rating and testing are given in the following publications:

——temperature rise and cooling in high external cooling medium temperature or at high altitude: GB 1094.2 for liquid-immersed transformers, and GB 1094.11 for dry-type transformers;

——external insulation at high altitude: GB 1094.3 for liquid-filled transformers, and

GB 1094.11 for dry-type transformers.

4.2 Normal service conditions

This part gives detailed requirements for transformers for use under the following conditions:

a) Altitude

A height above sea-level not exceeding 1000 m.

b) Temperature of cooling medium

The temperature of cooling air at the inlet to the cooling equipment not exceeding:

40℃ at any time;

30℃ monthly average of the hottest month;

20℃ yearly average.

and not below:

–25℃ in the case of outdoor transformers;

–25℃ in the case of outdoor transformers;

At any time, monthly average and yearly average are defined in 3.12.

The purchaser may specify a higher minimum temperature of cooling medium in which case the minimum temperature of cooling medium shall be stated on the rating plate.

Note 1: This paragraph above is intended to allow the use of an alternative insulating liquid which does not meet minimum temperature requirements in circumstances where the minimum temperature of –25 ℃ is not appropriate.

For water-cooled transformers, a temperature of cooling water at the inlet not exceeding:

25℃ at any time;

20℃ yearly average.

At any time and yearly average are defined in 3.12.

Further limitations, with regard to cooling are given for:

——liquid-immersed transformers in GB 1094.2;

——dry-type transformers in GB 1094.11.

Note 2: For transformers with both air/water and water/liquid heat exchangers, the temperature of cooling medium refers to the external air temperature rather than the water temperature in the intermediate circuit which may exceed the normal value

Note 3: The relevant temperature is at the inlet to the cooling equipment rather than the outside air temperature, this means that the user should take care that if the installation can create conditions where air recirculation from the output of the cooler can occur, that this is taken into account when assessing the cooling air temperature.

c) Wave shape of supply voltage

A sinusoidal supply voltage with a total harmonic content not exceeding 5% and an even harmonic content not exceeding 1%.

d) Load current harmonic content

Total harmonic content of the load current not exceeding 5% of rated current.

Note 4: Transformers where total harmonic content of the load current exceeds 5% of rated current, or transformers specifically intended to supply power electronic or rectifier loads should be specified according to GB/T 18494 series.

Note 5: Transformers can operate at rated current without excessive loss of life with a current harmonic content of less than 5 %, however it should be noted that the temperature rise will increase for any harmonic loading and may exceed rated rise.

e) Symmetry of three-phase supply voltage

For three-phase transformers, a set of three-phase supply voltages which are approximately symmetrical. Approximately symmetrical shall be taken to mean that the highest phase to phase voltage is no more than 1% higher than the lowest phase to phase voltage continuously or 2% higher for short periods (approximately 30min) under exceptional conditions.

f) Installation environment

An environment with a pollution rate (see GB/T 4109 and GB/T 26218.1) that does not require special consideration regarding the external insulation of transformer bushings or of the transformer itself. An environment not exposed to seismic disturbance which would require special consideration in the design. (This is assumed to be the case when the ground acceleration level is below 3ms-2 horizontally; or below 1.5ms-2 vertically) See GB/T 2424.25.

Where the transformer is installed in an enclosure not supplied by the transformer manufacturer remotely from the cooling equipment, for example in an acoustic enclosure, the temperature of the air surrounding the transformer is not exceeding 40℃ at any time.

Environmental conditions within the following definitions according to GB/T 4798.4:

——climatic conditions 4K2 except that the minimum external cooling medium temperature is –25℃;

——special climatic conditions 4Z2, 4Z4, 4Z7;

——biological conditions 4B1;

——chemically active substances 4C2;

—— mechanically active substances 4S3;

——mechanical conditions 4M4.

For transformers intended to be installed indoors, some of these environmental conditions may not be applicable.



5 Rating and General Requirements



5.1 Rated power

5.1.1 General

The rated power for each winding shall either be specified by the purchaser or the purchaser shall provide sufficient information to the manufacturer to determine the rated power at the enquiry stage.

The transformer shall have an assigned rated power for each winding which shall be marked on the rating plate. The rated power refers to continuous loading. This is a reference value for guarantees and tests concerning load losses and temperature rises.

If different values of apparent power are assigned under different circumstances, for example, with different methods of cooling, the highest of these values is the rated power.

A two-winding transformer has only one value of rated power, identical for both windings.

For multi-winding transformers, the purchaser shall specify the required power-loading combinations, stating, when necessary, the active and reactive outputs separately.

When the transformer has rated voltage applied to a primary winding, and rated current flows through the terminals of a secondary winding, the transformer receives the relevant rated power for that pair of windings.

The transformer shall be capable of carrying, in continuous service, the rated power (for a multi-winding transformer: the specified combination(s) of winding rated power(s)) under conditions listed in Clause 4 and without exceeding the temperature-rise limitations specified in GB 1094.2 for liquid immersed transformers.

Note 1: The interpretation of rated power according to this subclause implies that it is a value of apparent power input to the transformer - including its own absorption of active and reactive power. The apparent power that the transformer delivers to the circuit connected to the terminals of the secondary winding under rated loading differs from the rated power. The voltage across the secondary terminals differs from rated voltage by the voltage drop (or rise) in the transformer. Allowance for voltage drop, with regard to load power factor, is made in the specification of the rated voltage and the tapping range (see Clause 7 of GB/T 13499-2002).

Note 2: For a multi-winding transformer, half the arithmetic sum of the rated power values of all windings (separate windings, not auto-connected) gives a rough estimate of its physical size as compared with a two winding transformer.

5.1.2 Preferred values of rated power

Values of rated power should preferably be taken from the R10 series (……100, 125, 160, 200, 250, 315, 400, 500, 630, 800, 1000……).

5.1.3 Minimum power under alternative cooling modes

Where the user has a particular requirement for a minimum power under a particular cooling mode other than the cooling mode for rated power, this shall be stated in the enquiry.

The transformer shall be capable of carrying, in continuous service, the specified minimum power (for a multi-winding transformer: the specified combination(s) of winding rated power(s) under conditions listed in Clause 4, and under the specified cooling mode, without exceeding the temperature-rise limitations specified in GB 1094.2 for liquid immersed transformers.

Note: An example of this is where the transformer is required to operate at a particular minimum percentage of rated power with the forced cooling out of service (ONAN) to allow for the loss of auxiliary supply.

5.1.4 Loading beyond rated power

A transformer and its component parts in accordance with this part are able under some circumstances to carry loading beyond rated power. The method for calculating the permissible loading can be found in GB/T 1094.7 for liquid immersed transformers and in GB/T 1094.12 for dry-type transformers.

Any specific requirements for loading beyond rated power, operation at higher external cooling medium temperatures or reduced temperature rise limits shall be specified by the purchaser in the enquiry and the contract. Any additional tests or calculations required to verify compliance with these specific requirements shall also be specified.

Note 1: This option is intended to be used in particular to give a basis for design and guarantees concerning temporary emergency loading of power t transformers.

The bushings, tap-changers, current transformers and other auxiliary equipment shall be selected so as not to restrict the loading capability of the transformer.

Note 2: The relevant component standards GB/T 4109 for bushings and GB 10230.1 for tap-changers should be consulted for the loading capability of those components.

Note 3: These requirements do not apply to transformers for special applications, which do not need a loading capability beyond rated power. For these transformers, if such a capability is required, it should be specified.

5.2 Cooling mode

The user shall specify the cooling medium (air or water).

If the user has particular requirements for the cooling method(s) or cooling equipment, this shall be stated in the enquiry.

For additional information see GB 1094.2.

5.3 Load rejection on transformers directly connected to a generator

Transformers intended to be connected directly to generators in such a way that they may be subjected to load rejection conditions shall be able to withstand 1.4 times rated voltage for 5s at the transformer terminals to which the generator is to be connected.

5.4 Rated voltage and rated frequency

5.4.1 Rated voltage

The rated voltage shall either be specified by the purchaser or for special applications the purchaser shall provide sufficient information to the manufacturer to determine the rated voltage at the enquiry stage.

The transformer shall have an assigned rated voltage for each winding which shall be marked on the rating plate.

5.4.2 Rated frequency

The rated frequency shall be specified by the purchaser to be the normal undisturbed frequency of the network.

The rated frequency is the basis for the guaranteed values such as losses, impedance, and sound level.

5.4.3 Operation at higher than rated voltage and/or at other than rated frequency

Methods for the specification of suitable rated voltage values and tapping range to cope with a set of loading cases (loading power and power factor, corresponding line- to-line service voltages) are described in GB/T 13499.

Within the prescribed values of (Um), for the transformer windings, a transformer shall be capable of continuous operation at rated power without damage under conditions of 'overfluxing' where the value of voltage divided by frequency (V/Hz) exceeds the corresponding value at rated voltage and rated frequency by no more than 5%, unless otherwise specified by the purchaser.

At no load, transformers shall be capable of continuous operation at a V/Hz of 110% of the rated V/Hz.

At a current K times the transformer rated current (0≤K≤1), the overfluxing shall be limited in accordance with the following formula:



If the transformer is to be operated at V/Hz in excess of those stated above, this shall be identified by the purchaser in the enquiry

5.5 Provision for unusual service conditions

The purchaser shall identify in his enquiry any service conditions not covered by the normal service conditions. Examples of such conditions are:

——external cooling medium temperature outside the limits prescribed in 4.2;

——restricted ventilation;

——altitude in excess of the limit prescribed in 4.2;

——damaging fumes and vapours;

——steam;

——humidity in excess of the limit prescribed in 4.2;

——dripping water;

——salt spray;

——excessive and abrasive dust;

——high harmonic content of the load current exceeding the requirements of 4.2;

——distortion of the supply voltage waveform exceeding the limits of 4.2;

——unusual high frequency switching transients, see Clause 13;

——superimposed DC current;

——seismic qualification which would otherwise require special considerations in the design, see 4.2;

——extreme mechanical shock and vibrations;

——solar radiation;

——regular frequent energization in excess of 24 times per year;

——regular frequent short-circuits;

——regular frequent short-circuits;

——if a generator step up transformer is intended to be used in back -feed mode when not connected to the generator without protection on the lower voltage side;

——corrosion protection, according to the kind of installation and the installation environment (see 4.2), the purchaser should choose classes of protection in ISO 12944 or by agreement between purchaser and manufacturer;

——load rejection conditions for generator transformers more severe than those given in 5.3 above.

——Operation at extreme low temperature;

——special wiring modes;

——special installation positions and arrangement modes;

——installation at public places;

——special grounding mode of neutral points.

Transformer specification for operation under such abnormal conditions shall be subject to agreement between the supplier and purchaser.

Supplementary requirements, within defined limits, for the rating and testing of transformers designed for other than normal service conditions listed in Clause 4, such as high temperature of cooling air or altitude above 1000 m are given in GB 1094.2.

5.6 Highest voltage for equipment Um and dielectric tests levels

For line terminals, unless otherwise specified by the purchaser, Um shall be taken to be the value that equals to or slightly exceeds rated voltage of each winding.

For transformer windings with a highest voltage for equipment greater than (>) 72.5 kV, the purchaser shall specify whether any neutral terminals for that winding are to be directly earthed in service or not, and if not, the Um for the neutral terminals shall be specified by the purchaser.

Unless otherwise specified by the purchaser, dielectric test levels shall be taken to be the lowest applicable value corresponding to Um, given in GB 1094.3.

5.7 Additional information required for enquiry

5.7.1 Transformer classification

The kind of transformer, for example, separate winding transformer, auto-transformer or series transformer shall be specified by the user.

5.7.2 Winding connection and number of phases

The required winding connection shall be specified by the user in accordance with Clause 7.

If a stabilizing winding is required, it shall be specified by the purchaser. For star-star connected transformers or autotransformers, if the design has a closed magnetic circuit for zero sequence flux and no delta winding is specified, then the requirement shall be discussed between the manufacturer and the purchaser (see GB/T 13499).

Note: A closed magnetic circuit for zero sequence flux exists in a shell-form transformer, and in a core-form transformer with an unwound limb or limbs.

If there are requirements for high and low limits for the zero sequence impedance, this shall be stated by the purchaser and may influence the core configuration and the requirement for a delta winding. If the zero sequence requirements dictated the use of a delta connected winding that was not directly specified by the purchaser, then this shall be clearly stated by the manufacturer in the tender documents.

The transformer manufacturer shall not use a delta connected test winding if no delta winding has been specified, unless specifically agreed by the purchaser.

If there is a particular requirement for either a bank of single phase transformer or a three phase unit, then this shall be specified by the user; otherwise the manufacturer shall make it clear in the tender document what type of transformer is being offered.

5.7.3 Sound level

Where the purchaser has a specific requirement for a guaranteed maximum sound level, this shall be given in the enquiry and should preferably be expressed as a sound power level.

Unless otherwise specified, the sound level shall be taken as the no load sound level with all cooling equipment required to achieve rated power in operation. If an alternative cooling mode is specified (see 5.1.3) the sound level for each alternative mode may be specified by the purchaser and if specified shall be guaranteed by the manufacturer and measured on test.

The sound level in service is influenced by the load current (see GB/T 1094.10). If the purchaser requires a load current sound level measurement test or a guarantee of the total noise level of the transformers, including load noise, this shall be stated in the enquiry.

The sound level measured in the test according to GB/T 1094.10 shall not exceed the guaranteed maximum sound level. The guaranteed maximum sound level is a limit without tolerance.

5.7.4 Transport

5.7.4.1 Transport limitation

If transport size or weight limits apply, they shall be stated in the enquiry.

If any other special conditions apply during transportation, they shall be stated in the enquiry.

This might include a restriction on the transportation with insulating liquid or different environmental conditions expected to be experienced during transportation than those expected in service.

5.7.4.2 Transport acceleration

The transformer shall be designed and manufactured to withstand a constant acceleration of at least 3g in all directions without any damage, demonstrated by static force calculations based on a constant value of acceleration.

If the transport is not the responsibility of the manufacturer and an acceleration in excess of 3g is expected during transport, the accelerations and frequencies shall be defined in the enquiry. If higher accelerations are specified by the customer, the manufacturer shall demonstrate compliance by means of calculation.

If the transformer is intended to be used as a mobile transformer, this shall be stated in the enquiry.

Note: The use of impact or shock recorders during transportation for large transformer is common practice.

5.8 Components and materials

All components and materials used in the construction of the transformer shall comply with the requirements of the relevant standards where they exist unless otherwise agreed or specified. In particular bushings shall comply with GB/T 4109, tap-changers shall comply with GB 10230.1, and insulating liquid shall comply with GB 2536 for mineral oil or as agreed for other liquids. The electrical steel strip shall comply with GB/T 2521.



6 Requirements for Transformers Having a Tapped Winding



6.1 General – Notation of tapping range

The following subclauses apply to transformers in which only one of the windings is a tapped winding.

In a multi-winding transformer, the statements apply to the combination of the tapped winding with either of the untapped windings.

For transformers specified in accordance with 6.4.2, the notation shall be as specified by the purchaser in 6.4.2c).

In auto-connected transformers, tappings are sometimes arranged at the neutral which means that the effective number of turns is changed simultaneously in both windings. For such transformers, unless they are specified in accordance with 6.4.2, the tapping particulars are subject to agreement. The requirements of this subclause should be used as far as applicable.

Unless otherwise specified, the principal tapping is located in the middle of the tapping range. Other tappings are identified by their tapping factors. The number of tappings and the range of variation of the transformer ratio may be expressed in short notation by the deviations of the tapping factor percentages from the value 100 (for definitions of terms, see 3.5).

Example: A transformer with a tapped 220 kV winding with a tapping range of ±10 % having 17 tappings, symmetrically arranged around the rated voltage, is designated:

(220±8×1.25%)/35 kV

If the tapping range is specified asymmetrically around the rated voltage, this is designated as:

KV

Regarding the full presentation on the nameplate of data related to individual tappings, see Clause 8.

Some tappings may be 'reduced-power tappings' due to restrictions in either tapping voltage or tapping current. The boundary tappings where such limitations appear are called 'maximum voltage tapping' and 'maximum current tapping' [see Figures 1a), 1b) and 1c)].

6.2 Tapping voltage – tapping current (standard categories of tapping voltage variation. Maximum voltage tapping)

The short notation of tapping range and tapping steps indicates the variation range of the ratio of the transformer. But the assigned values of tapping quantities are not fully defined by this alone. Additional information is necessary. This can be given either in tabular form with tapping power, tapping voltage and tapping current for each tapping, or as text, indicating 'category of voltage variation' and possible limitations of the range within which the tappings are 'full-power tappings'.

The categories of tapping voltage variation are defined as follows:

a) Constant flux voltage variation (CFVV)

The tapping voltage in any untapped winding is constant from tapping to tapping. The tapping voltages in the tapped winding are proportional to the tapping factors. See Figure 1a).

b) Variable flux voltage variation (VFVV)

The tapping voltage in the tapped winding is constant from tapping to tapping. The tapping voltages in any untapped winding are inversely proportional to the tapping factor. See Figure 1b).

c) Combined voltage variation (CbVV)

In many applications and particularly with transformers having a large tapping range, a combination is specified using both principles applied to different parts of the range: combined voltage variation (CbVV). The change-over point is called 'maximum voltage tapping'. For this system the following applies:

CFVV applies for tappings with tapping factors below the maximum voltage tapping factor. VFVV applies for tappings with tapping factors above the maximum voltage tapping factor. See Figure 1c).



a) Constant Flux Voltage Variation (CFVV)

b) Variable Flux Voltage Variation (VFVV)

c) Combined Voltage Variation (CbVV) (from left to right)

From Figure 1c), the change-over point is shown in the plus tapping range. It constitutes both a maximum voltage tapping (UA), and a maximum current tapping (IB constant, not rising above the change-over point). An additional, optional maximum current tapping (in the CFVV range) is also shown.

Key:

UA and IA——the tapping voltage and tapping current in the tapped winding;

UB and IB——the tapping voltage and tapping current in the untapped winding;

SAB——the tapping power;

Abscissa——the tapping factor, percentage (indicating relative number of effective turns in tapped winding);

1——full-power tappings throughout the tapping range

2——'maximum-voltage tapping', 'maximum current tapping' and range of reduced power tappings.

Figure 1 Different Types of Voltage Variation

6.3 Tapping power (Full-power tappings – reduced-power tappings)

The following shall apply unless the voltage and current at each tapping is otherwise specified.

All tappings shall be full-power tappings, that is, the rated tapping current at each tapping shall be the rated power divided by the rated tapping voltage at each tap except as specified below.

In separate-winding transformers up to and including 2500 kVA with a tapping range not exceeding ±5%, the rated tapping current at all minus tappings shall be equal to the rated tapping current at the principal tapping. This means that the principal tapping is a 'maximum current tapping'.

In transformers with a tapping range wider than ±5%, restrictions may be specified on values of tapping voltage or tapping current which would otherwise rise considerably above the rated values. When such restrictions are specified, the tappings concerned will be 'reduced-power tappings'. This subclause describes such arrangements.

When the tapping factor deviates from 1, the tapping current for full-power tappings may rise above rated current on one of the windings. As Figure 1a) illustrates, this applies for minus tappings, on the tapped winding, under CFVV, and for plus tappings on the untapped winding under VFVV [Figure 1b)]. In order to limit the corresponding reinforcement of the winding in question, it is possible to specify a maximum current tapping. From this tapping onwards the tapping current values for the winding are then specified to be constant. This means that the remaining tappings towards the extreme tapping are reduced-power tappings [see Figures 1a), 1b) and 1c)].

Under CbVV, the 'maximum voltage tapping', the change-over point between CFVV and VFVV shall at the same time be a 'maximum current tapping' unless otherwise specified. This means that the untapped winding current stays constant up to the extreme plus tapping [Figure 1c)].

6.4 Specification of tappings in enquiry and order

6.4.1 General

The purchaser shall specify the requirements for tapping either according to 6.4.2 or 6.4.3.

The purchaser shall specify if the tap changer or tap changers are intended to be operated on load or de-energized.

Where variable flux voltage variation VFVV is used, it is normally only possible for the design ratio to match the specified ratio at two positions over the regulation range. The purchaser shall specify where the design ratio shall match the specified ratio, e.g. extreme taps, principal and maximum tap or principal and minimum tap. If not otherwise specified, the two extreme taps shall be the ratios to match.

Note: Subclause 6.4.2 requires the user to specify which winding is to be tapped and particular tapping powers. Subclause 6.4.3 defines overall voltage and current requirements and requires the manufacturer to select which winding or windings will be tapped. Such a specification may result in a variety of possible transformer designs. GB/T 13499 gives details of tapping arrangements and voltage drop calculations.

6.4.2 Constructional specification

The following data are necessary to define the design of the transformer:

a) which winding shall be tapped;

b) the number of steps and the tapping step (or the tapping range and number of steps). Unless otherwise specified, it shall be assumed that the range is symmetrical around the principal tapping and that the tapping steps in the tapped winding are equal. If for some reason, the design has unequal steps, this shall be indicated in the tender;

c) the category of voltage variation and, if combined variation is applied, the change-over point ('maximum voltage tapping', see 6.2);

d) whether maximum current limitation (reduced power tappings) shall apply, and if so, for which tappings.

Instead of items c) and d), tabulation of the same type as used on the rating plate may be used to advantage (see example in Annex E).

6.4.3 Functional specification

This type of specification is intended to allow the purchaser to specify operational requirements and not the category of voltage variation or which winding is to be tapped.

This method of specification is not applicable to separate-winding transformers up to and including 2500 kVA with a tapping range not exceeding ±5%.

The following information shall be given by the purchaser in the enquiry in addition to the rated voltage and rated power defined in Clause 5:

a) Direction of power flow (can be both directions).

b) The number of tapping steps and the size of the tapping step expressed as a percentage of the rated voltage at the principal tapping. If the tapping range is not symmetrical about the principal tapping then this shall be indicated. If the tapping steps are not equal across the range then this shall be indicated.

Note 1: It may be that the range of variation and the number of steps is more important than achieving the exact voltage at the principal tap. In this case the range of variation and the number of steps may be specified. For example +5% to –10% in 11 steps.

c) Which voltage shall vary for the purpose of defining rated tapping voltage.

Note 2: The rated tapping voltage is needed to determine the impedance base for each tap. Where the functional method of specification is adopted, the rated tapping voltage cannot be used to determine the rated tapping power.

d) Any requirements for fixing the ratio of turns between two particular windings on a more than two winding transformer.

e) Minimum full load power factor (this affects the voltage drop of the transformer).

f) Whether any tapping or range of tappings can be reduced power tappings.

The manufacturer will choose the arrangement of windings, the winding or windings that are tapped. The transformer shall be able to supply the rated current on the secondary winding on all tapping positions consistent with the above operating conditions, without exceeding the temperature rise requirements defined by GB 1094.2.

The transformer shall be designed to withstand without damage the voltages and fluxes arising from the above specified loading conditions (including any specified overload conditions). A calculation showing that this condition is satisfied shall be supplied to the purchaser on request.

An example is given in Annex E (Example 4).

Alternatively, the user shall submit a set of loading cases with values of active and reactive power (clearly indicating the direction of power flow), and corresponding on-load voltages. These cases shall indicate the extreme values of voltage ratio under full and reduced power (see “the six-parameter method” of GB/T 13499). Based on this information, the manufacturer will then select the tapped winding and specify rated quantities and tapping quantities in his tender proposal. An agreement shall be reached between the manufacturer and the purchaser on the design tapping quantities.

6.5 Specification of short-circuit impedance

For transformers with no tappings exceeding a voltage variation of ±5% from the principal tapping, the short-circuit impedance of a pair of windings shall be specified at the principal tapping only, either in terms of ohms per phase Z or in percentage terms z referred to the rated power and rated voltage of the transformer (see 3.7.1). Alternatively, the impedance may be specified in accordance with one of the methods below.

For transformers with tappings exceeding a voltage variation of ±5% from the principal tapping, impedance values expressed in terms of Z or z shall be specified for the principal tapping and the extreme tapping(s) exceeding ±5%. On such transformers, these values of impedance shall also be measured during the short-circuit impedance and load losses test (see 11.4) and shall be subject to the tolerances given in Clause 10. If the impedance is expressed in percentage terms z, this shall be referred to the rated tapping voltage (at that tapping) and the rated power of the transformer (at the principal tapping).

Note 1: The selection of an impedance value by the user is subject to conflicting demands: limitation of voltage drop versus limitation of overcurrent under system fault conditions. Economic optimization of the design, bearing in mind loss, leads towards a certain range of impedance values. Parallel operation with an existing transformer requires matching impedance (see GB/T 13499).

Note 2: If an enquiry contains a specification of not only the impedance at the principal tapping but also its variation across the tapping range, this can impose an important restriction on the design of the transformer (the arrangement of the windings in relation to each other and their geometry). The transformer specification and design also need to take into account that large changes in impedance between taps can reduce or exaggerate the effect of the tappings.

Alternatively maximum and minimum impedances in terms of z or Z may be specified for each tapping across the whole tapping range. This may be done with the aid of a graph or a table.(See Annex F). The boundaries shall where possible be at least as far apart as to permit the double-sided tolerances of Clause 10 to be applied on a median value between them. Measured values shall not fall outside the boundaries, which are limits without tolerance.

Note 3: The specified maximum and minimum impedances shall allow an impedance tolerance at least as great as the tolerances given in Clause 10 but where necessary a tighter tolerance may be used by agreement between manufacturer and purchaser.

Note 4: Basing the impedance on the rated tapping voltage and the rated power of the transformer at the principal tapping means that the relationship between ohms per phase Z and percentage impedance z will be different for each tap and will also depend on which winding the voltage variation is specified. Great care is therefore needed to ensure that the specified impedance is correct. This is particularly important for transformers specified with tapping powers different to rated power at principal tapping.

6.6 Load loss and temperature rise

Load loss and temperature rise shall be in accordance with:

a) If the tapping range is within ±5%, and the rated power not above 2500 kVA, load loss guarantees and temperature rise refer to the principal tapping only, and the temperature rise test is run on that tapping.

b) If the tapping range exceeds ±5% or the rated power is above 2500 kVA, the guaranteed losses shall be stated on the principal tapping position, unless otherwise specified by the purchaser at the enquiry stage. If such a requirement exists, it shall be stated for which tappings, in addition to the principal tapping, the load losses are to be guaranteed by the manufacturer. These load losses are referred to the relevant tapping current values. The temperature-rise limits are valid for all tappings, at the appropriate tapping power, tapping voltage and tapping current.

The temperature-rise type test shall be carried out on one tapping only, unless otherwise specified. It will, unless otherwise agreed, be the 'maximum current tapping' (which is usually the tapping with the highest load loss). The maximum total loss on any tapping is the test power for determination of liquid temperature rise during the temperature rise test, and the tapping current for the selected tapping is the reference current for determination of winding temperature rise above liquid. For information about rules and tests regarding the temperature rise of liquid-immersed transformers, see GB 1094.2.

In principle, the temperature-rise type test shall demonstrate that the cooling equipment is sufficient for dissipation of maximum total loss on any tapping, and that the temperature rise over external cooling medium temperature of any winding, at any tapping, does not exceed the specified maximum value.

Note 1: For an autotransformer, the maximum current in the series and common windings are usually at two different tap positions. Therefore an intermediate tap position may be selected for test to allow the requirements of GB 1094.2 to be met on both windings during the same test.

Note 2: For some tapping arrangements, the tapping winding is not carrying current in the maximum current tapping position. Therefore, if the temperature rise of the tapping winding needs to be determined, another tapping may be selected or an extra test may be agreed.



7 Connection and Connection Symbols



7.1 Connection and connection symbols for three-phase transformers and for single phase transformers connected in a three phase bank

7.1.1 Connection symbol

The star, delta, or zigzag connection of a set of phase windings of a three-phase transformer or of windings of the same voltage of single-phase transformers associated in a three-phase bank shall be indicated by the capital letters Y, D or Z for the high-voltage (HV) winding and small letters y, d or z for the intermediate and low-voltage (LV) windings.

If the neutral point of a star-connected or zigzag-connected winding is brought out, the indication shall be YN (yn) or ZN (zn) respectively. This also applies to transformers where the neutral end connections for each phase winding is brought out separately but are connected together to form a neutral point for service.

For an auto-connected pair of windings, the symbol of the lower voltage winding is replaced by the letter a.

Open windings in a three-phase transformer (that are not connected together in the transformer but have both ends of each phase winding brough

Foreword I
1 Scope
2 Normative References
3 Terms and Definitions
4 Service Conditions
5 Rating and General Requirements
6 Requirements for Transformers Having a Tapped Winding
7 Connection and Connection Symbols
8 Rating Plates
9 Safety, Environmental and other Requirements
10 Tolerances
11 Tests
12 Electromagnetic Compatibility (EMC)
13 High Frequency Switching Transients
Annex A (Informative) Technical Differences between This Part and IEC 60076-1: 2011 and Their Reasons
Annex B (Informative) Vacuum Deflection Test and Pressure Deflection Test for Liquid Immersed Transformers in IEC 60076-1:
Annex C (Informative) Examples of Three-phase Transformer Connections
Annex D (Informative) Technical Requirements to be Provided with Enquiry and Order
Annex E (Informative) Examples of Specifications for Transformers with Tappings
Annex F (Informative) Specification of Short-circuit Impedance by Boundaries
Annex G (Normative) Temperature Correction of Load Loss
Annex H (Informative) Facilities for Future Fitting of Condition Monitoring Systems to Transformers
Annex I (Informative) Environmental and Safety Considerations
Bibliography

电力变压器 第1部分：总则
1 范围
GB 1094的本部分适用于三相及单相变压器(包括自耦变压器)，但不包括某些小型和特殊变压器，如：
——额定容量小于1 kVA的单相变压器和5 kVA的三相变压器；
——所有绕组额定电压均不高于1 000 V的变压器；
——互感器；
——电机车牵引变压器；
——起动变压器；
——试验变压器；
——电焊变压器；
——防爆矿用变压器；
——深水(浸水)用变压器。
当某些类型的变压器(尤其是所有绕组电压均不高于1 000 V的工业用特种变压器)没有相应的标准时，本部分可以整体或部分适用。
本部分不涉及变压器安装在公共场所的要求。
对于具有相关标准的变压器和电抗器，本部分只适用于被其产品标准明确提及可相互参考的内容范围。这些产品(标准)包括：
——电抗器(GB/T 1094.6)；
——干式变压器(GB 1094.11)；
——自保护变压器(IEC 60076-13)；
——充气式电力变压器(IEC 60076-15)；
——风力发电用变压器(GB 1094.16)；
——牵引变压器和牵引电抗器(GB/T 25120)；
——工业用变流变压器(GB/T 18494.1)；
——HVDC用换流变压器(GB/T 18494.2)。
本部分中有几处规定或建议涉及的是某些替换方案、附加技术方案或程序需要达成的协议。这类协议需要由制造方与用户达成。问题应在早期提出，协议应包含在技术规范中。
2 规范性引用文件
下列文件对于本文件的应用是必不可少的。凡是注日期的引用文件，仅注日期的版本适用于本文件。凡是不注日期的引用文件，其最新版本(包括所有的修改单)适用于本文件。
GB 1094.2 电力变压器 第2部分：液浸式变压器的温升(GB 1094.2-2013，IEC 60076—2：2011，MOD)
GB 1094.3 电力变压器 第3部分：绝缘水平、绝缘试验和外绝缘空气间隙(GB 1094.3-2003，IEC 60076-3：2000，MOD)
GB 1094.5 电力变压器 第5部分：承受短路的能力(GB 1094.5-2008，IEC 60076-5：2006，MOD)
GB/T 1094.10 电力变压器 第10部分：声级测定(GB/T 1094.10-2003，IEC 60076-10：2001，MOD)
GB 1094.11 电力变压器 第11部分：干式变压器(GB 1094.11-2007，IEC 60076-11：2004，MOD)
GB/T 2521 冷轧取向和无取向电工钢带(片)(GB/T 2521-2008，IEC 60404-8-7：1998、IEC60404-8-4：1998，MOD)
GB 2536 电工流体变压器和开关用的未使用过的矿物绝缘油(GB 2536-2011，IEC 60296：2003，MOD)
GB/T 2900.15 电工术语 变压器、互感器、调压器和电抗器(GB/T 2900.15-1997，neqIEC 60050-421：1990、IEC 60050-321：1986)
GB/T 4109交流电压高于1 000 V的绝缘套管(GB/T 4109-2008，IEC 60137：2008，MOD)
GB/T 4798.4 电工电子产品应用环境条件 第4部分：无气候防护场所固定使用(GB/T 4798.4-2007，IEC 60721-3-4：1995，MOD)
GB l0230.1分接开关第1部分：性能要求和试验方法(GB 10230.1-2007，IEC 60214-1：2003，MOD)
GB/T 19001质量管理体系要求(GB/T 19001-2008，IS0 9001：2008，IDT)
3 术语和定义
GB/T 2900.15界定的以及下列术语和定义适用于本文件。为了便于使用，以下重复列出了GB/T 2900.15中的某些术语和定义，且个别术语和定义进行了修改。
3.1 一般术语
3.1.1
电力变压器 power transformer
具有两个或两个以上绕组的静止设备，为了传输电能，在同一频率下，通过电磁感应将一个系统的交流电压和电流转换为另一个系统的交流电压和电流，通常这些电流和电压的值是不同的。
注：改写GB/T 2900.15-1997，定义3.1.1。
3.1.2
自耦变压器 auto-transformer
至少有两个绕组具有公共部分的变压器。
[GB/T 2900.15-1997，定义3.1.15]
注：如果需要表示变压器不是自耦联结时，可用术语如：独立绕组变压器或双绕组变压器表示。
3.1.3
串联变压器 series transformer
具有一个与线路串联以改变线路电压值和(或)相位的串联绕组及一个励磁绕组的变压器，它不同于自耦变压器。
注1：改写GB/T 2900.15-1997，定义3.1.8。
注2：在本部分的以前版本中，串联变压器被称作增压变压器。
3.1.4
液浸式变压器 liquid-immersed type transformer
铁心和绕组都浸入液体中的变压器。
[GB/T 2900.15-1997，定义3.1.4]
3.1.5
干式变压器 dry-type transformer
铁心和绕组都不浸入绝缘液体中的变压器。
[GB/T 2900.15-1997，定义3.1.5]
3.1.6
液体保护系统 liquid preservation system
在液浸式变压器中，为适应液体的热膨胀而设置的保护系统。
注：有的可以减少或防止液体与外部空气接触。
3.1.7
规定值 specified value
采购方订货时规定的值。
3.1.8
设计值 design value
根据匝数比设计得到的绕组匝数或计算得到的阻抗、空载电流或其他参数的期望值。
3.1.9
适用于变压器绕组的设备最高电压 highest voltage for equipment applicable to a transformer winding
Um
三相系统中相问最高电压的方均根值。
[GB 1094.3-2003，定义3.1]
3.2 端子和中性点
3.2.1
端子 terminal
用于将绕组与外部导线相连接的导电部件。
3.2.2
线路端子 line terminal
接到电网线路导体用的接线端子。
[GB/T 2900.15-1997，定义5.5.1]
3.2.3
中性点端子 neutral terminal
中性点端子包括：
a)对于三相变压器或由单相变压器组成的三相组，指连接星形联结或曲折形联结公共点(中性点)的端子；
b)对于单相变压器，指连接网络中性点的端子。
注：改写GB/T 2900.15-1997，定义5.5.2。
3.2.4
中性点 neutral point
对称电压系统中，通常处于零电位的一点。
3.2.5
对应端子 corresponding terminal
变压器不同绕组标注相同字母或符号的各端子。
[GB/T 2900.15-1997，定义2.1.28]
3.3 绕组
3.3.1
绕组 winding
构成与变压器标注的某一电压值相对应的电气线路的一组线匝。
注1：改写GB/T 2900.15-1997，定义4.3.1。
注2：对于三相变压器，指三个相绕组的组合(见3.3.3)。
3.3.2
分接绕组 tapped winding
有效匝数可以逐级改变的绕组。
3.3.3
相绕组 phase winding
构成三相绕组的一个相的线匝组合。
注1：改写GB/T 2900.15-1997，定义4.3.16。
注2：“相绕组”一词不应与某一心柱上所有线圈的组装体混同。
3.3.4
高压绕组1) high-voltage windin9；HV winding
具有最高额定电压值的绕组。
[GB/T 2900.15-1997，定义4.3.2]
3.3.5
低压绕组1) low-voltage winding；LV winding
具有最低额定电压值的绕组。
[GB/T 2900.15-1997，定义4.3.3]
注：对于串联变压器，较低额定电压的绕组可能具有较高的绝缘水平。
3.3.6
中压绕组1) intermediate-voltage winding
多绕组变压器中的一个绕组，其额定电压介于高压绕组额定电压和低压绕组额定电压之间。
[GB/T 2900.15-1997，定义4.3.4]
3.3.7
辅助绕组 auxiliary winding
只承担比变压器额定容量小得多的负载的绕组。
[GB/T 2900.15-1997，定义4.3.11]
3.3.8
稳定绕组 stabilizing winding
在星形一星形联结或星形一曲折形联结的变压器中，用来减小零序阻抗的三角形联结的辅助绕组，见3.7.3。
注1：改写GB/T 2900.15-1997，定义4.3.12。
注2：此绕组只有在不与外部做三相连接时，才称为稳定绕组。
1) 运行中从电源接收有功功率的绕组被称为“一次绕组”，将有功功率传递给负载的绕组被称为“二次绕组”。这些术语不说明哪个绕组的额定电压高，并且除了需要指明有功功率流动方向外不宜使用这些术语。额定容量通常小于二次绕组的变压器的其他绕组，通常被称为“第三”绕组，见3.3.8。
3.3.9
公共绕组 c001.on winding
自耦变压器绕组的公共部分。
[GB/T 2900.15-1997，定义4.3.13]
3.3.10
串联绕组 series winding
自耦变压器或串联变压器中，拟串接到电路中的那部分绕组。
注：改写GB/T 2900.15-1997，定义4.3.14。
3.3.11
励磁绕组 energizing winding
向串联绕组(串联变压器)或相关绕组提供电能的绕组。
注：改写GB/T 2900.15-1997，定义4.3.15。
3.3.12
自耦联结绕组 auto-connected windings
自耦变压器中的串联绕组和公共绕组。
3.4额定值
3.4.1
额定值 rating
对某些参数指定的值，用于限定变压器在本部分规定条件下的运行，并作为试验的基准和制造方的保证值。
3.4.2
额定参数 rated quantities
其数值用于确定额定值的某些参数(电流、电压等)。
注1：对于有分接的变压器，如无另行规定，则额定参数均指主分接(见3.5.2)。与其他具体分接有类似意义的相应参数叫分接参数(见3.5.9)。
注2：如无另行规定，电压和电流用其方均根值表示。
3.4.3
绕组的额定电压 rated voltage of a winding
Ur
在处于主分接(见3.5.2)的带分接绕组的端子间或不带分接的绕组端子间，指定施加的电压或空载时感应出的电压。对于三相绕组，是指线路端子间的电压。
注1：改写GB/T 2900.15-1997，定义2.1.4。
注2：当施加在一个绕组上的电压为额定值时，在空载情况下，所有绕组同时出现各自的额定电压值。
注3：对于拟联结成星形三相组的单相变压器或接到线路与中性点之间的单相变压器，用相-相电压除以 来表示
额定电压。如：
kV
注4：对于要接到网络相间的单相变压器，用相-相电压表示额定电压。
注5：对于三相串联变压器的串联绕组，如果绕组设计为开路绕组(见3.10.5)，则按照绕组结成星结来给出额定电压。
3.4.4
额定电压比 rated voltage ratio 一个绕组的额定电压与另一个具有较低或相等额定电压绕组的额定电压之比。
注：改写GB/T 2900.15-1997，定义2.1.5。
3.4.5
额定频率 rated frequency
fr
变压器设计所依据的运行频率。
注：改写GB/T 2900.15-1997，定义2.1.6。
3.4.6
额定容量 rated power
Sr
某一个绕组的视在功率的指定值，与该绕组的额定电压一起决定其额定电流。
注：双绕组变压器的两个绕组具有相同的额定容量，即这台变压器的额定容量。
3.4.7
额定电流 rated current
Ir
由变压器额定容量(Sr)和额定电压(Ur)推导出的流经绕组线路端子的电流。
注1：改写GB/T 2900.15-1997，定义2.1.7。
注2：对于三相变压器绕组，其额定电流表示为：

注3：对于联结成三角形结法以形成三相组的单相变压器绕组，其额定电流表示为线电流除以 ：

注4：对于不联结成三相组的单相变压器，额定电流为：

注5：变压器开口绕组的额定电流为额定容量除以相数与开目绕组额定电压的积：
式中：
n——相数。
3.5 分接
3.5.1
分接 tapping
在带分接绕组的变压器中，该绕组的每一个分接连接均表示该分接的绕组有一确定的有效匝数，也表示该分接绕组与任何其他匝数不变的绕组间有一确定的匝数比。
注：在所有分接中，有一个是主分接，其他分接用各自相对主分接的分接因数来表示其与主分接的关系。见以下定义。
3.5.2
主分接 principal tapping
与额定参数相对应的分接。
[GB/T 2900.15-1997，定义2.1.12]
3.5.3
分接因数(与指定的分接相对应的) tapping factor(corresponding to a given tapping)
比值：
Ud/Ur(分接因数)或100Ud/Ur(用百分数表示分接因数)。
式中：
Ur——该绕组的额定电压(见3.4.3)；
Ud——在不带分接绕组施加额定电压时，处于指定分接位置的绕组端子间在空载下所感应出的电压。
注1：对于串联变压器，分接因数是指对应于指定分接的串联绕组的电压与Ur的比值。
注2：改写GB/T 2900.15—1997，定义2.1.13。
3.5.4
亚分接 plus tapping
分接因数大于1的分接。
[GB/T 2900.15—1997，定义2.1.14]
3.5.5
负分接 minus tapping
分接因数小于1的分接。
[GB/T 2900.15-1997，定义2.1.15]
3.5.6
分接级 tapping step
两相邻分接间以百分数表示的分接因数之差。
[GB/T 2900.15-1997，定义2.1.16]
3.5.7
分接范围 tapping range
用百分数表示的分接因数与100相比的变化范围。
注：如果分接因数百分值变化范围是从100+n变到100-b，则此分接范围为：+n％、-b％；当a=b时，为±a％。
[GB/T 2900.15-1997，定义2.1.17]
3.5.8
分接电压比(一对绕组的) tapping voltage ratio(of a pair of windings)
当带分接绕组是高压绕组时，其分接电压比等于额定电压比乘以该绕组的分接因数。
当带分接绕组是低压绕组时，其分接电压比等于额定电压比除以该绕组的分接因数。
[GB/T 2900.15-1997，定义2.1.18]
注：按定义，虽然额定电压比不小于1，但当额定电压比接近于1时，某些分接的分接电压比有可能小于1。
3.5.9
分接参数 tapping quantities
表示某一分接(除主分接以外)的分接工作能力的参数。
注1：变压器内任何一个绕组(不只是带分接的绕组)都有分接参数(见6.2和6.3)。
其分接参数是：
——分接电压(与额定电压类似，见3.4.3)；
——分接容量(与额定容量类似，见3.4.6)；
——分接电流(与额定电流类似，见3.4.7)。
注2：改写GB/T 2900.15-1997，定义2.1.20。
3.5.10
满容量分接 full-power tapping
分接容量等于额定容量的分接。
[GB/T 2900.15-1997，定义2.1.24]
3.5.11
降低容量分接 reduced-power tapping
分接容量低于额定容量的分接。
[GB/T 2900.15-1997，定义2.1.25]
3.5.12
有载分接开关 on-load tap-changer；OLTC
适合于在变压器励磁或负载下进行操作的用来改变变压器绕组分接连接位置的一种装置。
[GB/T 2900.15-1997，定义5.6.1]
3.5.13
无励磁分接开关 de-energized tap-changer；DETC
适合于只在变压器无励磁(与系统隔离)时进行操作的用来改变变压器绕组分接连接位置的一种装置。
注：改写GB/T 2900.15-1997，定义5.6.2。
3.5.14
最大许可分接运行电压 maximum allowable tapping service voltage
在额定频率和相应的分接容量下，在任何特定分接位置变压器能够连续耐受而无损害的电压设计值。
注1：该电压受Um的限制。
注2：正常情况下，该电压被限定到额定分接电压的105％，但若用户在关于分接(见6.4)的技术要求中有明确要求或根据6.4.2的结果，则更高的电压是允许的。
3.6 损耗和空载电流
损耗及空载电流值均是指主分接上的(但另指定其他分接时除外)。
3.6.1
空载损耗 no-load loss
当额定频率下的额定电压(分接电压)施加到一个绕组的端子上，其他绕组开路时所吸取的有功功率。
注：改写GB/T 2900.15-1997，定义2.1.33。
3.6.2
空载电流 no-load current
当额定频率下的额定电压(分接电压)施加到一个绕组的端子上，其他绕组开路时流经该绕组线路端子的电流方均根值。
注1：对于三相变压器，是流经三相端子电流的算术平均值。
注2：通常用占该绕组额定电流的百分数来表示。对于多绕组变压器，是以具有最大额定容量的那个绕组为基准的。
注3：改写GB/T 2900.15-1997，定义2.1.34。
3.6.3
负载损耗 load loss
在一对绕组中，当额定电流(分接电流)流经一个绕组的线路端子，且另一绕组短路时在额定频率及参考温度下(见11.1)所吸取的有功功率。此时，其他绕组(如果有)应开路。
注1：对于双绕组变压器，只有一对绕组组合和一个负载损耗值。
对于多绕组变压器，具有与多对绕组组合相应的多个负载损耗值(见GB/T 13499-2002的第7章)。整台变压器的总负载损耗值与某一指定的绕组负载组合相对应。通常它不能在试验中直接测出。
注2：当绕组组合对中两个绕组的额定容量不同时，其负载损耗以额定容量小的那个绕组中的额定电流为基准，而且应指出参考容量。
注3：改写GB/T 2900.15-1997，定义2.1.31。
3.6.4
总损耗 total losses
空载损耗与负载损耗之和。
注1：辅助装置的损耗不包括在总损耗中，并应单独说明。
注2：改写GB/T 2900.15-1997，定义2.1.30。
3.7 短路阻抗和电压降
3.7.1
一对绕组的短路阻抗 short-circuit impedance of a pair of windings
在额定频率及参考温度下，一对绕组中某一绕组端子之间的等效串联阻抗2=R+jX(Ω)。确定此值时，另一绕组的端子短路，而其他绕组(如果有)开路。对于三相变压器，表示为每相的阻抗(等值星形联结)。
注1：对于带分接绕组的变压器，短路阻抗是指指定分接的。如元另行规定，则是指主分接的。
注2：此参数可用无量纲的相对值来表示，即表示为该对绕组中同一绕组的参考阻抗Zref的分数值z。用百分数表示：

式中:

公式对三相和单相变压器都适用。
U——Z和Zref所属绕组的电压(额定电压或分接电压)；
Sr——额定容量基准值。
此相对值也等于短路试验中为产生相应额定电流(或分接电流)时所施加的电压与额定电压(或分接电压)之比。此电压称为该对绕组的短路电压(见GB/T 2900.15-1997中的2.1.37)。通常用百分数表示。
注3：改写GB/T 2900.15-1997，定义2.1.37。
3.7.2
规定负载条件下的电压降或电压升 voltage drop of rise for a specified load condition
绕组的空载电压与同一绕组在规定负载及规定功率因数时，在其端子上产生的电压之间的算术差，此时，另一绕组施加的电压等于：
——额定电压，此时变压器接到主分接(绕组的空载电压等于额定电压)；
——分接电压，此时变压器接到其他分接。
此差值通常表示为该绕组空载电压的百分数。
注：对于多绕组变压器，此电压降或电压升不仅与该绕组的负载和功率因数有关，也与其他绕组的负载和功率因数有关(见GB/T 13499)。
[GB/T 2900.15-1997，定义2.1.40]
3.7.3
零序阻抗(三相绕组的) zero-sequence impedance(of a three-phase winding)
额定频率下，三相星形或曲折形联结绕组中，连接在一起的线路端子与其中性点端子间的以每相欧姆数表示的阻抗。
注1：由于零序阻抗还取决于其他绕组的连接方法和负载，因而零序阻抗可以有几个值。
注2：零序阻抗可随电流和温度变化，特别是在没有任何三角形联结绕组的变压器中。
注3：零序阻抗也可用与(正序)短路阻抗同样的方法表示为相对值(见3.7.1)。
注4：改写GB/T 2900.15-1997，定义2.1.41。
3.8 温升
温升 temperature rise
所考虑部位的温度与外部冷却介质的温度之差(见GB 1094.2)。
注：改写GB/T 2900.15-1997，定义2.1.46。
3.9 绝缘
变压器绝缘的有关术语和定义，按GB 1094.3规定。
3.10 联结
3.10.1
星形联结 star connection
三相变压器的每个相绕组的一端或组成三相组的单相变压器的三个具有相同额定电压绕组的一端连接到一个公共点(中性点)，而另一端连接到相应的线路端子。
注1：改写GB/T 2900.15-1997，定义4.4.1。
注2：星形联结有时叫做Y联结或星结。
3.10.2
三角形联结 delta connection
三相变压器的三个相绕组或组成三相组的单相变压器的三个具有相同额定电压的绕组相互串联连接成一个闭合回路。
注1：改写GB/T 2900.15-1997，定义4.4.2。
注2：三角形联结有时叫做D联结或角结。
3.10.3
开口三角形联结 open-delta connection
三相变压器的三个相绕组或组成三相组的三台单相变压器的三个具有相同额定电压的绕组相互串联连接，但三角形的一个角不闭合。
EGB/T 2900.15-1997，定义4.4.4]
3.10.4
曲折形联结 zigzag connection
三相变压器的每个相绕组包括两部分，第一部分联结成星结，第二部分串联在第一部分与线路端子间。两部分如下布置，每相的第二部分绕在与第一部分不同的心柱上，并接到第一部分上。
注1：见附录C，附录C中两部分绕组的电压相同。
注2：曲折形联结有时叫做2联结。
3.10.5
开路绕组 open windings
不在三相变压器内部相互联结的相绕组。
注；改写GB/T 2900.15-1997，定义4.4.5。
3.10.6
相位移(三相绕组的) phase displacement(of a three-phase winding)
当正序电压施加于按字母顺序或数字顺序标志的高压端子时，低压(中压)绕组和高压绕组中性点(真实的或假设的)与相应线路端子间电压相量的角度差。这些相量均假定按逆时针旋转。
注1：改写GB/T 2900.15-1997，定义2.1.27。
注2：见第7章和附录C。
注3：以高压绕组相量为基准，任何其他绕组的相位移均用钟时序数表示。即当高压绕组向量位于“12”时，其他绕
组向量用钟时序数表示(钟时序数越大，表示相位越滞后)。
3.10.7
联结组标号 connection symbol
用一组字母和钟时序数指示高压、中压(如果有)及低压绕组的联结方式，是表示中压、低压绕组对高压绕组相位移关系的通用标识。
注：改写GB/T 2900.15-1997，定义2.1.26。
3.11 试验分类
3.11.1
例行试验 routine test
每台变压器都要承受的试验。
3.11.2
型式试验 type test
在一台有代表性的变压器上所进行的试验，以证明被代表的变压器也符合规定要求(但例行试验除外)。如果变压器生产所用图样相同、工艺相同、原材料相同，在同一制造厂生产，则认为其中一台可以代表。
注1：与特定型式试验明确不相关的设计差异，不应要求重新进行该型式试验。
注2：如果设计差异引起特定型式试验的数值和应力降低，且制造方和用户双方同意，则这个差异不要求重新进行
型式试验。
注3：对于20 MVA以下，且Um≤72.5 kV的变压器，若能证明符合型式试验要求，则可以允许有较大的设计差异。
3.11.3
特殊试验 special test
除型式试验和例行试验外，按制造方与用户协议所进行的试验。
注：所有特殊试验可以按照用户在询价和订货时的规定，在一台或特定设计的所有变压器上进行。
3.12 与冷却有关的气象数据
3.12.1
冷却介质最高温度(任何时刻的) temperature of cooling medium(at any time)
通过多年测量得到的冷却介质的最高温度。
3.12.2
月平均温度 monthly average temperature
某一月份中，日最高温度的平均数与日最低温度的平均数之和的一半的多年统计值。
3.12.3
年平均温度 yearly average temperature
全年中，各月平均温度之和的1/12。
3.13 其他术语
3.13.1
负载电流 load current
运行条件下，任意绕组中电流的方均根值。
3.13.2
总谐波含量 total harmonic content
所有谐波的方均根值与基波方均根值(E1、I1)之比。
电压总谐波含量：

电流总谐波含量：

式中：
Ei——第i次谐波的电压方均根值；
Ii——第i次谐波的电流方均根值。
3.13.3
偶次谐波含量 even harmonic content
所有偶次谐波方均根值与基波方均根值(E1、I1)之比。
电压偶次谐波含量：

电流偶次谐波含量：

式中：
E2i——第2i次谐波的电压方均根值；
I2i——第2i次谐波的电流方均根值。
4 使用条件
4.1 概述
变压器的正常使用条件见4.2中的规定。变压器设计中需要考虑的任何特殊使用条件见5.5的规定。特殊使用条件包括高海拔、极高或极低的冷却介质温度、湿热带气候、地震活动、严重污染、非正常的负载电压或电流波形、强太阳辐射和间歇性负载。还可能涉及运输、储存和安装，如：质量和空间限制(见附录D)。
额定值和试验的补充规定见下列标准：
——外部冷却介质温度高或高海拔时的温升和冷却：对于液浸式变压器见GB 1094.2，对于干式变压器见GB 1094.11；
——高海拔时的外绝缘：对于液浸式变压器见GB 1094.3，对于干式变压器见GB 1094.11。
4.2 正常使用条件
本部分给出的变压器的详细要求，是用于下列使用条件的：
a) 海拔
海拔不超过1 000 m。
b)冷却介质温度
冷却设备入口处的冷却空气温度不超过：
任何时刻：40℃；
最热月平均：30℃；
年平均：20℃；
并且不低于：
户外变压器：-25℃；
变压器和冷却器都拟用于户内的变压器:-5℃。
月平均温度和年平均温度的规定见3.12。
用户可以规定较高的最低冷却介质温度，在此情况下，最低的冷却介质温度应在铭牌上示出。
注1：上述规定是允许采用替代绝缘液体，即：当最低环境温度不能满足-25℃时，允许使用替代绝缘液体。
对于水冷变压器，入口处冷却水温度不应超过：
任何时刻：25℃。
年平均：20℃。
任何时刻和年平均温度的规定见3.12。
对于冷却方面的进一步的规定：
——液浸式变压器见GB 1094.2；
——干式变压器见GB 1094.11。
注2：对于既有空气/水又有水/液体热交换器的变压器，冷却介质温度是指外部空气温度，而不是指内部回路中的水温，该水温可能超过正常值。
注3：冷却介质温度是冷却设备入口处的温度，而不是外部空气温度，这意味着用户在安装时应关注空气是否具有从冷却设备外部产生再循环的条件，在评估冷却空气温度时需要将其考虑进去。
c) 电源电压波形
电源电压波形应为正弦波，总谐波含量不超过5％，偶次谐波含量不超过1％。
d)负载电流谐波含量
负载电流总谐波含量不超过额定电流的5％。
注4：总谐波含量超过负载额定电流5％的变压器，或按照GB/T 18494系列标准，拟向电力电子或整流器负载供电的变压器，均应进行说明。
注5：变压器可以在电流谐波含量不超过额定电流5％的情况下运行而不会有过多寿命损失，然而需要注意的是任何谐波负载下的温升可能会增加并超过额定温升。
e)三相电源电压的对称
对于三相变压器，一组三相电源电压应近似对称。近似对称意味着连续的最高相间电压比最低相间电压不应高1％，或在异常的短期(近似30 min)情况下，不应高2％。
f) 安装环境
变压器套管或变压器外部绝缘不需要特殊考虑环境的污秽等级(见GB/T 4109和GB/T 26218.1)。安装环境不应有需要特殊考虑的地震干扰(这里认为地表加速度水平方向低于3 ms-2；垂直方向低于1.5 ms-2)，见GB/T 2424.25。
若变压器安装于距离冷却设备较远的由用户提供的封闭环境中，如：隔音室，则变压器周围空气温度在任何时候均不应超过40℃。
下列定义中的环境条件见GB/T 4798.4：
——气候条件4K2，但最低外部冷却介质温度为-25℃；
——特殊气候条件422、424、427；
——生物学条件4B1；
——化学活性物质4C2；
——机械活性物质4S3；
——机械条件4M4。
对于户内安装的变压器，上述环境条件中可能某些不适用。