Test Item: CT Winding Measurement and Protection Verification Before Commissioning of 35kV Line in 500kV Substation

Test Equipment: HTA-3300 Three-phase Digital Intelligent High-current Source, HTV-6000 Three-phase Digital Intelligent High-voltage Source, YD-300 Wireless Telemetry Voltmeter-Ammeter Phase Indicator

I Wiring Method

1. Current Source WiringClose the isolation switch DL, open the isolation switch 1G and the earthing switch 1GD, ground the P2 terminal, and connect the three-phase currents IA, IB, IC from the P1 ground bar using the HTA-3300 Three-phase Digital Intelligent High-current Source.

△ Three-phase Digital Current Source Wiring Diagram

△ Current Source Wiring Terminals

△ HTA-3300 Three-phase Digital Intelligent High-current Source Wiring Layout

2. Open the isolation switches connecting other bays to the 35kV busbar.

II Test Process

The HTA-3300 Three-phase Digital Intelligent High-current Source is powered by AC380V, and can be operated wirelessly via the panel buttons or the YD-300 Wireless Telemetry Voltmeter-Ammeter Phase Indicator. Inject the primary current value through the line CT, and check the amplitude and phase on the current source display screen or the YD-300.

1. Set Parameters on the Remote Control Host: Output three-phase currents of 160A, 200A and 240A in positive sequence.

2. Click to start the test, the current source will start outputting, and read the corresponding values on the YD-300. Apply the primary current value, read the corresponding value on the secondary protection device, and conduct the line CT winding measurement and protection verification.

III Test Report

Tests were carried out on 6 bays on site. The applied current values were the same for the first 5 bays, and different for the 6th bay. The CT ratio of the first 5 bays was 600:1, and the ratio of the 6th bay was 1200:1. During the test, the secondary values collected by the YD-300 were basically consistent with those displayed on the protection device, and the test data were normal.

△ Test Result Table

By applying high current and voltage to the primary circuit of the newly-built substation, the verification of the entire primary and secondary circuits, polarities and phases is completed. This solves the problem of difficult load organization before substation commissioning and effectively ensures the success of one-time power transmission.