Substation, a place where voltage is changed. In order to transmit the electric energy from the power plant to a distant place, the voltage must be raised to become high-voltage electricity, and the voltage must be lowered as needed near the user. The work of raising and lowering the voltage is done by the substation. In the power system, the substation is the gathering point of power transmission and distribution. The equipment of the substation is cut off or connected, and the voltage is changed or adjusted. Substations are mainly divided into: step-up substations, main network substations, secondary substations, and distribution substations.
The equipment that transforms the voltage in the substation is the transformer. In addition, the equipment in the substation also includes switchgear for opening and closing circuits, busbars for collecting current, transformers for measurement and control, instruments, relay protection devices and lightning protection devices. , dispatching communication devices, etc., and some substations also have reactive power compensation equipment. The main equipment and connection methods of substations vary according to their functions.
The substations are classified into: 500 kV, 400 kV, 330 kV, 220 kV, 115, kV 110 kV, 66 kV, kV35 kV, 33 kV, 11 kV, etc.
Substation test is an important link in the operation and maintenance of substation, and it is one of the effective means to ensure the safe operation of substation. It is divided into acceptance test and preventive test. The regular preventive test period of substation is one year, including main transformer, GIS , disconnector, switchgear, instrument transformer(CT/PT), lightning arrestor, grounding rods and conductors, cable and generator, etc., the following lists the specific test items and corresponding test instruments of the substation.
1. Power Transformer: The function of transforming voltage, converting the high voltage of AC to low voltage (step-down transformer). (There is also a step-up transformer that converts low voltage into high voltage)
2. Circuit Breaker: Cut off and connect the no-load current and load current in the high-voltage circuit under normal conditions, and cooperate with the protection device and automatic device when the system fails. safe operation of the system.
3. Disconnect Switch: Reliably isolate the electrical equipment that needs to be repaired from the live part of the power grid with the isolation switch, so that the electrical equipment to be repaired and the power supply have an obvious disconnection point to ensure the safety of the maintenance work. Change the operation mode to perform the switch-off operation. For example, in the circuit with double busbar operation, the disconnector can be used to switch the equipment or line from one group of busbars to another group of busbars. Makes and cuts low-current circuits.
4. Lightning Mast : prevent direct lightning, so that the electrical equipment (substation equipment) within their protection range is less likely to be shielded by direct lightning.
5. Surge Arrestor: Through the action of parallel discharge gap or non-linear resistance, it can cut the intrusion flow wave and reduce the overvoltage amplitude of the protected equipment. Lightning arresters can be used to protect against atmospheric overvoltages and operating overvoltages.
6. Busbars: Busbars are conductors which connect equipment within the substation
7. Capacitor: Improve the power factor of the power grid and improve the voltage quality.
8. Current/Voltage Transformer: Transformer equipment that converts large current into small current for the application of instruments and protection devices.
9.. Substation commissioning test items and test equipment Voltage transformer: Transformer equipment that converts high voltage into low voltage for the application of instruments and protection devices.
The test items are required for 110kV/220kV substation acceptance and maintenance testing(with corresponding tester types):
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Test Object |
Testing Item |
Tester Type |
Tester Link
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Cable |
Cable AC Hipot Testing |
JYCX |
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Cable Insulation Resistance Testing |
JYM KYORITSU |
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Transformer |
Insulation Resistance of Winding |
JYM KYORITSU |
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DC Leakage Testing in 1min |
JYDHV |
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Winding Resistance Testing |
JYR50S |
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Winding Deformation Testing |
JYP |
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Turns Ratio Testing |
JYT-A |
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AC Hipot Testing |
JYCX |
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Short Circuit Impedance Testing |
JYW6300 |
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Dan Delta Testing |
JYC |
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Oil Breakdown Voltage (BDV)Testing |
JY6611 |
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Oil Tan Delta Testing |
GTD-61A |
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Switchgear |
Circuit Breaker/Disconnector Resistance |
JYL-200B |
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Relay |
Relay Performance |
JY7003G |
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On-load |
On-load Switchgear Testing |
JYK-I |
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Tap Changer Dynamic Testing |
JYK-I |
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Instrument Transformer |
Current Transformer (CT)Testing |
JYH-C |
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Potential Transformer (PT)Testing |
JYH-C |
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Surge Arrestor |
Zinc Oxide Characteristics Testing |
JY6800 |
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1mA DC Reference Voltage |
JYDHV |
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Capacitor |
Capacitor Current |
JY6700 |
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Capacitor Inductance |
JY6700 |
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Ground Grid |
Grounding Down Lead Earth |
JYD |
