Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.
This standard is developed in accordance with the rules given in GB/T 1.1-2009.
This standard replaces GB/Z 24845-2009 Specification of metal-oxide surge arresters without gaps for 1,000 kV AC system.
In addition to editorial changes, the following main technical changes have been made with respect to GB/Z 24845-2009:
——Relevant parameters are added as to surge arresters with rated voltages of 804kV and 780 kV (see 7.1);
——External insulation withstand test, residual voltage test, operating duty test, power-frequency voltage versus time characteristic test, short-circuit current test, seismic test, bending load test, etc. are modified according to IEC (latest edition) and recent research results (see Clause 9, and Clause 10 of GB/Z 24845-2009);
——The equalizing capacitor test, environmental test and creepage distance inspection are added (see Clause 9);
——The abnormal operating conditions of the surge arrester are added (see Annex A);
——The calculation formula in the voltage distribution test is modified (see Annex B, and Annex A of GB/Z 24845-2009);
——The special requirements are added as to porcelain-housed surge arresters for 1,000 kV a.c. systems used as post insulators (see Annex C);
——The technical requirements are added as to monitors for metal-oxide surge arresters without gaps for 1,000 kV a.c. systems (see Annex D).
This standard was proposed by the China Electricity Council.
This standard is under jurisdiction of SAC/TC 569 National Technical Committee on Ultra-High Voltage AC Transmission of Standardization Administration of China.
The previous edition of this standard is as follows:
——GB/Z 24845-2009.
Specification of metal-oxide surge arresters without gaps for 1,000 kV a.c. system
1 Scope
This standard specifies the operating conditions, technical requirements, inspection rules, test methods and packaging and transport of metal-oxide surge arresters without gaps for 1,000 kV a.c. system.
This standard is applicable to porcelain-housed metal-oxide surge arresters without gaps for power stations (referred to as "surge arresters") and gas-insulated metal-enclosed metal-oxide surge arresters without gaps (referred to as "GIS arresters") designed to limit the overvoltage in 1,000 kV a.c. systems.
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/T 191 Packaging - Pictorial marking for handling of goods
GB/T 7354 Partial discharge measurements
GB/T 7674 Gas-insulated metal-enclosed switchgear for rated voltages of 72.5kV and above
GB/T 8905 The guide for management and measuring SF6 gas in electrical equipment
GB/T 11022-2011 Common specifications for high-voltage switchgear and controlgear standards
GB/T 11023 Test guide of SF6 gas tightness for high-voltage switchgear
GB/T 11032-2010 Metal-oxide surge arresters without gaps for A.C. systems
GB/T 12022 Industrial sulfur hexafluoride
GB/T 13540-1992 Anti-seismic characteristic test for high-voltage switchgear
GB/T 16927.1 High-voltage test techniques - Part 1: General definitions and test requirements
GB/T 26218.1 Selection and dimensioning of high-voltage insulators intended for use in polluted conditions - Part 1: Definitions, information and general principles
GB/T 26218.2 Selection and dimensioning of high-voltage insulators intended for use in polluted conditions - Part 2: Ceramic and glass insulators for a. c. systems
GB 50150 Standard for hand-over test of electric equipment - electric equipment installation engineering
GB 50260-2013 Code for seismic design of electrical installations
JB/T 10492 Monitoring devices for metal-oxide surge arresters
IEC 60099-4:2014 Metal-oxide surge arresters without gaps for a.c. systems
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 11032-2010, GB/T 11022-2011 and the following apply. For the convenience of application, some terms and definitions given in GB/T 11032-2010 and GB/T 11022-2011 are listed repeatedly as follows.
3.1
housing and sheds
3.1.1
housing
external insulating part of an surge arrester, which provides the necessary creepage distance and protects the internal parts from the environment
Note: housing may consist of several parts providing mechanical strength and protection for the internal parts against the environment.
[GB/T 11032-2010, definition in 3.46.1]
3.1.2
shed
insulating part projecting from the housing; it is intended to increase the creepage distance
[GB/T 11032-2010, definition in 3.46.2]
3.2
porcelain-housed surge arrester
surge arrester which uses porcelain as housing material and is provided with fittings and sealing systems
[GB/T 11032-2010, definition in 3.59]
3.3
bending moment
horizontal force acting on the surge arrester housing multiplied by the vertical distance between the mounting base (lower end of lower flange) of the surge arrester housing and the point of application of the force
[GB/T 11032-2010, definition in 3.61]
3.4
terminal line force
force perpendicular to the longitudinal axis of the surge arrester and measured at the centerline of the surge arrester
[GB/T 11032-2010, definition in 3.62]
3.5
breaking load
force perpendicular to the longitudinal axis of a porcelain-housed surge arrester, leading to mechanical failure of the surge arrester housing
[GB/T 11032-2010, definition in 3.64]
3.6
internal parts
metal-oxide resistor assembly with support structure and internal voltage equalization system (if any)
3.7
seal (gas/water tightness)
ability to prevent substances that have an effect on electrical and/or mechanical properties from entering the interior of the surge arrester
[GB/T 11032-2010, definition in 3.70]
3.8
maximum applied voltage ratio of an arrester under power-frequency voltage loading
maximum applied voltage ratio of an arrester under power-frequency voltage loading η = the maximum non-uniformity coefficient of voltage distribution declared by the surge arrester × the power-frequency continuous operating voltage / the power-frequency reference voltage
3.9
gas-insulated metal enclosed surge arrester
GIS arrester
gas-insulated metal-enclosed metal oxide arresters, with its interior free from any series or parallel discharge gaps and filled with a gas other than air
Notes:
1 The gas pressure is normally higher than 1 bar = 105 Pa.
2 This surge arrester is used in gas-insulated switchgear.
[GB/T 11032-2010, definition in 3.51]
3.10
housing of GIS arrester
external metal-enclosed part of the GIS arrester, it is connected to the ground and protects internal components from environmental influences
3.11
rated density of insulating gas Dre (or rated pressure of insulating gas Pre)
density, Dre (or pressure, Pre) of the insulating gas specified by the manufacturer, filled into the surge arrester before commissioning or after the air supply and converted to standard atmospheric conditions (+20 ℃, 101.3 kPa) It can be expressed by relative pressure or absolute pressure
[GB/T 11032-2010, definition in 11.3.1]
3.12
the minimum functional density of insulating gas Dme (the minimum functional pressure of insulating gas Pme)
minimum functioning density, Dme (or minimum functioning pressure Pme) of the insulating gas, as specified by the manufacturer and converted to standard atmospheric conditions (+20 ℃, 101.3 kPa). It can be expressed by relative pressure or absolute pressure. If the insulating gas is below this density, the rated characteristics of the surge arrester will not be guaranteed and the gas needs to be replenished in time.
[GB/T 11032-2010, definition in 11.3.2]
3.13
absolute leakage rate, F
leakage amount of gas in unit time, expressed in Pa·L/s
[GB/T 11022-2011, definition in 3.6.6.5]
3.14
permissible leakage rate, Fp
maximum allowable absolute leakage rate specified by the manufacturer
[GB/T 11022-2011, definition in 3.6.6.6]
3.15
relative leakage rate, Frel
absolute leakage rate relative to the total amount of gas in the system filled with rated filling pressure (or density), expressed in yearly or daily percentage
[GB/T 11022-2011, definition in 3.6.6.6]
4 Marking
The nameplate of the metal-oxide surge arrester shall cover at least the following information:
——model;
——continuous operating voltage;
——rated frequency;
——DC reference voltage;
——rated short-circuit current;
——manufacturer's name;
——assembly position marks of the components of the surge arrester;
——manufacturing date;
——No..
5 Standard ratings
5.1 Standard rated voltage
Rated voltage of the surge arrester (effective value): 828 kV, 804 kV and 780 kV.
Notes:
1 Surge arresters with rated voltages of 804 kV and 780 kV may be considered if the project does have requirements and the power-frequency overvoltage of the practical project is relatively low, but they need to be checked by overvoltage calculation and verified by test.
2 The power-frequency overvoltage shall not exceed 1.3 p.u. or 1.4 p.u. and the actuation time of relay protection shall not exceed 0.5 s if the surge arrester with a rated voltage of 828 kV is selected; it is recommended that the power-frequency overvoltage shall not exceed 1.2 p.u. if the arrester with a rated voltage of 804 kV or 780 kV is selected.
5.2 Standard rated frequency
The standard rated frequency is 50 Hz.
5.3 Standard nominal discharge current
The standard 8/20 μs nominal discharge current is 20 kA.
6 Operating conditions
6.1 Normal operating conditions
6.1.1 Environmental conditions
Environment conditions for using surge arresters:
a) the ambient temperature is within a range of -40℃～+40℃;
b) the radiation of sunlight;
Note: the influence of the maximum sunlight intensity (1.1 kW/m2) has been taken into consideration by preheating the test specimen in the type test. If any other heat sources exist around the surge arrester, the use of the surge arrester shall subject to the negotiation between the supplier and demander.
c) the altitude shall be no greater than 1,000m.
d) the maximum wind speed shall not exceed 35 m/s (apply the 100-year average maximum wind speed to the position 10 m above the ground for 10 min);
e) the icing thickness shall be no greater than 20 mm;
f) areas with a pollution class of d and below;
g) areas with a seismic fortification intensity of 7 and below;
h) installation site: outdoors;
i) installation method: upright type.
6.1.2 System conditions
System conditions for using surge arresters:
a) rated frequency of the system: 50 Hz;
b) nominal voltage of the system: 1,000 kV;
c) maximum operating voltage of the system: 1,100 kV;
d) short-circuit current level of the system: 63 kA;
e) earthing method of neutral points of the system: direct earthing
f) the power-frequency voltage applied between the terminals of the surge arrester for a long time shall not exceed the continuous operating voltage of the surge arrester.
6.2 Abnormal operating conditions
Under abnormal operating conditions, the design, manufacture and use of surge arresters shall be specially considered, and the use of this standard shall be subject to negotiation between the supplier and the demander. See Annex A for abnormal operating conditions.
7 Technical requirements
7.1 Technical parameters
See Table 1 for the main technical parameters of surge arresters.
Table 1 Main technical parameters of typical surge arresters
Rated voltage of surge arrester (effective value)/kV 828 804a 780a
Nominal system voltage (effective value)/kV 1,000 1,000 1,000
Continuous operating voltage of arrester (effective value)/kV 638 638 638
Nominal discharge current of arrester (peak value)/kA 20 20 20
Steep current impulse residual voltage (peak value)/ kV ≤1,782 ≤1,730 ≤1,679
Lightning impulse residual voltage (peak value)/kV ≤1,620 ≤1,573 ≤1,526
2 kA Switching impulse residual voltage (peak value)/kV ≤1,460 ≤1,418 ≤1,375
DC reference voltage b/kV ≥1,114 ≥1,082 ≥1,049
Leakage current at 0.75 times D.C reference voltage/μA ≤ 200 ≤ 200 ≤ 200
Power-frequency reference current (peak value)c/ mA 24 24 24
Power-frequency reference voltage (peak value/ ), kV
≥828 ≥804 ≥780
Continuous current Resistive current (fundamental wave) /mA ≤ 3 ≤ 3 ≤ 3
Total current (effective value)/mA ≤ 20 ≤ 20 ≤ 20
Long duration impulse current withstand/A 8,000 8,000 8,000
High-current impulse withstand current value/kA 100/column 100/column 100/column
Number of parallel columns 4d 4d 4d
Non-uniformity coefficient of voltage distribution ≤ 1.15 ≤ 1.15 ≤ 1.15
Non-uniformity coefficient of current distribution between columns ≤ 1.10 ≤ 1.10 ≤ 1.10
Insulation resistance of insulating base/MΩ ≥2,000 ≥2,000 ≥2,000
a Surge arresters with rated voltages of 804 kV and 780 kV may be considered if the project does have requirements and the power-frequency overvoltage of the practical project is relatively low, but they shall be checked by overvoltage calculation and verified by test, see 5.1 for details.
b For a typical 4-column parallel structure, the DC reference current is typically 8 mA.
c For a typical 4-column parallel structure, the power-frequency reference current is typically 24 mA.
d 4-column parallel structure is a proven typical structure. As long as the requirements of this standard are met, different parallel-resistor column numbers may also be used.
7.2 Insulation performance of surge arrester
The insulation withstand voltage of the insulating part inside the surge arrester and that of the porcelain housing of the surge arrester shall meet those specified in Table 2.
Table 2 Insulation test voltages In: kV
Rated lightning impulse withstand voltage (peak value) 2,400
Rated switching impulse withstand voltage (peak value) 1,800
Rated short-duration (1 min) power-frequency withstand voltage (effective value) 1,100
7.3 Reference voltages
7.3.1 Power-frequency reference voltages
The power-frequency reference current and the power-frequency reference voltage of the surge arrester shall meet those specified in Table 1 and shall be published in the manufacturer's information.
7.3.2 DC reference voltage
The DC reference current and the DC reference voltage of the surge arrester shall meet those specified in Table 1 and shall be published in the manufacturer's information. In the routine test, the minimum and maximum reference voltages of the surge arrester under the selected reference current shall be specified.
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Marking
5 Standard ratings
6 Operating conditions
7 Technical requirements
8 Test requirements
9 Type test (design test)
10 Routine test
11 Acceptance test
12 Regular test
13 Sampling test
14 Gas-insulated metal enclosed metal-oxide surge arresters without gaps (GIS arresters)
15 Nameplate, packaging, transport and storage
Annex A (Normative) Abnormal operating conditions
Annex B (Normative) Voltage distribution test method
Annex C (Normative) Special requirements for porcelain-housed surge arresters for 1,000 kV a.c. systems used as post insulators
Annex D (Normative) Monitors for metal-oxide surge arresters without gaps for 1,000 kV a.c. systems
