1 Scope
This document specifies the basic voltages and test methods used for DC electric traction systems. This document applies to the supply line voltage of DC electric traction systems under normal operating conditions. This document applies mainly to the following electrified transports:
a) Electrified transport in industrial and mining enterprises (including underground tunnel transport);
b) urban rail transport, e.g. metro electric vehicles. Light rail trains, trams. Low-speed maglev trains, etc.
c) urban trolleybuses, dual-energy trams;
d) suburban (including satellite towns) and local railway electrified railways.
This document does not apply to:
a) the rated voltage at which signals (measured values) are to be expressed or transmitted;
b) the rated voltage of components or equipment units in electrical equipment; c) cranes. Mobile platforms. Rated voltages for ropeway cable cars.
Note 1 DC voltages in this document are average values.
Note 2. DC voltages in this document are ripple-free DC values. DC with a sinusoidal ripple content of no more than ten percent of the root mean square value is usually referred to as "ripple-free DC".
2 Normative references
The contents of the following documents constitute essential provisions of this document through the normative references in the text. Among them, note the date of the reference document, only the date of the corresponding version applicable to this document; do not note the date of the reference document, its latest version (including all the revision of the list) applicable to this document.
GB/T 156 Standard voltage
IEC 61133:2016 Railway facilities, railway vehicles, Specification for testing of rolling stock on completion of construction and before entry into service (Railway applica-tions - Rolling stock - Testing of rolling stock on completion of construction and before entry intoservice)
3 Terms and definitions
The terms defined in GB/T 156 and the following terms and definitions apply to this document.
3.1
Electric traction systemThe traction system in which electrical energy is supplied to the power car by an external power source.
Note: An electric traction system is a combination of a traction substation, current transformer, contact network and power car operating at a common voltage, consisting mainly of:
Contact network system;
The feed-back circuit of an electric traction system,
The operating track of a non-electric traction system, which is adjacent to and electrically connected to the operating track of an electric traction system;
electrical installations for supplying power from the contact network, either directly or via transformers,
Electrical installations on power plants or (traction) substations used solely for the generation or distribution of electricity to the contact network;
Electrical installations at switchgear stations.
4 Basic voltages of DC traction power supply systems
4.1 Voltages
4.1.1 Nominal system voltages and permissible limit values for the main voltage system (excluding overvoltages) are shown in Table 1, Main voltage system:
a) The duration between the voltage of the lowest constant voltage Uma and the lowest non-constant voltage Umane shall not exceed 2 min.
b) The duration between the highest constant voltage Ua and the highest non-constant voltage Uas should not exceed 5 mnin.
c) Under no-load conditions, the (traction) substation bus voltage shall be lower than or equal to the maximum non-constant voltage Umaa , and the voltage supplied to the train pantograph shall be determined in accordance with Table 1 and its requirements.
d) Under normal operating conditions, the voltage should be within the range Uain≤U≤U.nz.
e) Under abnormal operating conditions, voltages in the range Umane ≤ U ≤ Umin in Table 1 shall not cause any damage and malfunction.
f) For non-special cycles, if the voltage reaches the maximum constant voltage Uxr: and the maximum non-constant voltage Unaxa between, it shall be treated as lower or equal to the maximum constant voltage U level. For the following non-persistent cases, the voltage is only between the maximum constant voltage Ua and the maximum non-constant voltage Umez:
1 regenerative braking;
2) movement of the voltage regulation system, e.g. mechanical tap changeover switch.
Minimum operating voltage: In the case of abnormal operation, the minimum non-constant voltage Unans is the lowest limit of the contact network voltage, when rolling stock is allowed to operate.
h) The recommended value of the under-voltage automatic trip setting: the setting value of the under-voltage relay or on-board equipment in the fixed installation should be set at (85% to 95%) Una .
Note: The use of on-board train power limiting devices can limit the occurrence of low voltage in overhead lines.
4.2 Voltage U spectrum
The maximum value of voltage U depending on the duration is shown in Figure 1.
4.3 Variation of voltage
4.3.1 Voltage variation
The range of voltage variation is inherent to the electrified railway due to the traction load, the structure of the traction power network and the structure of the public distribution and railway power network.
4.3.2 Contact network voltage drop
Voltage drops are caused by faults in the contact network or in the public distribution system.
The vast majority of voltage drops have a duration of less than 1 s and are less than half of U
4.3.3 Interruptions in the power supply
Power supply interruptions can be classified as follows:
(a) Pre-arranged supply interruptions. The customer is notified in advance and is allowed to carry out the planned work on the distribution system.
b) Accidental interruptions. These are caused by persistent or transient faults, mostly related to extreme events, equipment failures or disturbances. Incidental power supply interruptions can be subdivided into:
1) long-term interruptions caused by persistent faults (>3 min); 2) short-term faults caused by transient faults (≤3 min).
4.3.4 Voltage interruptions
4.3.4.1 Short-term voltage interruptions
Under normal operating conditions, short-term voltage interruptions are generally caused by tripping of circuit breakers and automatic reclosing after fault detection.
The frequency of voltage interruptions varies from tens to hundreds of times throughout the year and approximately 70% of the interruptions may last for less than 10 s.
4.3.4.2 Long-term interruptions of voltage
Incident interruptions are usually caused by external events or actions. It is difficult to indicate typical values for the duration of long interruptions.
Under normal operating conditions, voltage interruptions of more than 3 min are likely to be less frequent than other faults throughout the year. For pre-arranged interruptions, typical values are not given because they are notified in advance.
4.3.5 Voltage distortions
Voltage distortions are caused by the traction system, auxiliary loads, current transformers and the common distribution system.
4.3.6 Voltage surges
Voltage distortion is a single sudden change in the average value of the voltage between two successive voltage levels.
5 Test methods
5.1 Measurement of contact network voltage
5.1.1 Contact network voltage for rolling stock
The test for rolling stock is carried out in accordance with Chapter 9 of IEC 61133:2016.
5.1.2 Ground devices
The methods and requirements for testing the voltage of ground devices are shown in Table 4.
5.2 Measurement of voltage variations and interruptions
4.3.1, 4.3.2, 4.3.3 and 4.3.4 do not require type tests or routine tests.
If problems with voltage quality are apparent after voltage has been put in, it is advisable to measure specifically at the site where the problem exists, to monitor the voltage at a representative period of time after normal input and to analyse the results according to the following
a) Voltage surges and voltage drops in the contact network. Voltages below the minimum non-constant voltage Uma are captured and the data analysed in order to provide voltage levels as millisecond durations and percentage changes in U.
Tabulation of the lowest voltage levels and the most adverse conditions during the duration. Identify any faults or periods when the listed changes are connected to the railway system power supply or distribution system.
Bibliography
Foreword
1 Scope
2 Normative references
3 Terms and definitions
4 Basic voltages of DC traction power supply systems
5 Test methods
Bibliography
