380V 400kVA Series Resonant Test System Overcurrent Protection

Series resonance test device

1. Subject
1. 10kV/300mm2 cable 3km AC withstand voltage test, capacitance ≤1.1265uF, test frequency 30-300Hz, test voltage 22kV, test time 15 min.
2. AC withstand voltage test of 10kV/2500kVA main transformer, capacitance ≤0.01uF, test frequency 45-65Hz, test voltage not exceeding 28kV, test time 1min.
3. AC withstand voltage test of 10kV switch, busbar and other substation equipment, the test frequency is 30-300Hz, the test voltage does not exceed 42kV, and the test time is 1min.
4. 35kV/300mm2 cable 2km AC withstand voltage test, capacitance ≤0.361uF, test frequency 30-300Hz, test voltage 52kV, test time 60min.
5. AC withstand voltage test of 35kV/6300kVA main transformer, capacitance ≤0.01uF, test frequency 45-65Hz, test voltage 68kV, test time 1min.
6. AC withstand voltage test of 35kV switchgear, circuit breaker and other substation equipment, the test frequency is 30-300Hz, the test voltage does not exceed 95kV, and the test time is 1min.

7.220kV circuit breaker AC withstand voltage test, test frequency 30-300Hz, test voltage 368kV, test time 1min.

2. The main technical parameters and functions of the system
1. Rated capacity: 400kVA;
2. Rated voltage: 27kV; 50kV; 400kV;
3. Rated current: 2A;
4. Allow continuous working time: 60min under rated current;
5. The quality factor of the device itself: Q≥30 (when f=45Hz);
6. System measurement accuracy: effective value 1.0;
7. Input power: 50Hz; three-phase 380V
8. Working frequency of variable frequency power supply: 40-300Hz;
9. Frequency resolution: 0.1Hz;
10. Frequency instability: ≤0.1%;
11. It has overcurrent, overvoltage and flashover protection for the tested product;
12. Ambient temperature: -150C -40 0C, relative humidity: ≤90%RH, altitude ≤2000 meters.

3. Selection and determination of system parameters
Single section reactor is 54kVA/27kV/2A/50H, a total of four sections verification:
1) For a 10kV/300mm2/3km cable, the capacitance is 1.1265μF, the test voltage is 22KV, and four reactors are used in parallel. At this time, the inductance of the reactor is 12.5H, then:
Test frequency: f=1/2π√LC=42.41Hz
Test current: I=ωCXU test=2πfCXU test=2×3.14×42.41×1.1265×22×10-3=6.6A
2) 10kV/2500kVA main transformer AC withstand voltage test, the capacitance does not exceed 0.01μF, the test voltage is 28kV, the reactor is connected in series with two sections, the inductance is 113H, then:
Test frequency: f=1/2π√LC=149.72Hz
Test current: I=ωCXU test=2πfCXU test=2×3.14×149.72×0.01×28×10-3=0.26A

3) AC withstand voltage test of 10kV switch, busbar and other substation equipment, the test frequency is 30-300Hz, the capacitance does not exceed 0.015μF, the test voltage does not exceed 42kV, the reactor adopts two series connection, the inductance is 113H, then:
Test frequency: f=1/2π√LC=122.25Hz
Test current: I=ωCXU test=2πfCXU test=2×3.14×122.25×0.015×42×10-3=0.48A
4) For the 35kV/300mm2/2km cable, the capacitance is 0.361μF, the test voltage is 52KV, and two reactors are used in series and two parallel. At this time, the inductance of the reactor is 56.5H, then:
Test frequency: f=1/2π√LC=35.24Hz
Test current: I=ωCXU test=2πfCXU test=2×3.14×35.24×0.361×52×10-3=4.16A
5) 35kV/6300kVA main transformer AC withstand voltage test, the capacitance does not exceed 0.01μF, the test voltage is 68kV, the reactor is connected in series with four sections and the inductance is 240H, then:
Test frequency: f=1/2π√LC=83.88Hz
Test current: I=ωCXU test=2πfCXU test=2×3.14×83.88×0.01×68×10-3=0.54A
6) 35kV switch, circuit breaker, etc. AC withstand voltage test, the test voltage is 95kV, the reactor is connected in series with four sections and the inductance is 240H, then:
Test frequency: f=1/2π√LC=83.88Hz
Test current: I=ωCXU test=2πfCXU test=2×3.14×83.88×0.015×95×10-3=0.75A
7) AC withstand voltage test of 220kV switches, circuit breakers, etc., the capacitance does not exceed 5000pF, the test voltage is 368kV, the reactor is 50kVA/50kV/100H eight series in series, the inductance is 960H, then:
Test frequency: f=1/2π√LC=72.64Hz
Test current: I=ωCXU test=2πfCXU test=2×3.14×72.64×0.005×368×10-3=0.84A