Test subject and test requirements
1. AC withstand test for a 35kV/400mm2 cable for 1.2km, with capacitance ≤ 0.258uF, test frequency 30-300Hz, test voltage 52kV, test duration 60 minutes.
2. The AC withstand test for the 35kV/60000kVA main transformer, with an capacitance of ≤ 0.02uF, is conducted at a frequency of 45-65Hz, with the test voltage not exceeding 68kV, and the test duration is 1 minute.
3. An AC withstand test for a 10kV/500mm2 cable over a distance of 1.5km. The capacitance is ≤ 0.692uF. The test frequency is 30 – 300Hz. The test voltage is 22kV. The test duration is 5 minutes.
4. The AC withstand voltage test for a 10kV/25MW thermal power generator, with an capacitance of ≤ 0.15uF. The test frequency is 45 – 65Hz, the test voltage does not exceed 23kV, and the test duration is 1 minute.
Determination of the capacity of the series resonance withstand voltage test device
Design four reactors. Each reactor will have a capacity of 40.5kVA/27kV/1.5A/86H, and the total capacity of the device will be 162kVA.
Verification of test conditions for the series resonance withstand voltage test device:
The AC withstand test for a 35kV/400mm2 cable over a distance of 1.2km has an capacitance of ≤ 0.258uF. The test frequency is 30 – 300Hz, the test voltage is 52kV, and the test duration is 60 minutes.
Using two sections of reactor connected in series (with mutual inductance coefficient of 1.05) and two groups connected in parallel, then: L = 86 × 2 × 1.05 / 2 = 90.3 H.
Then:
Test frequency: f = 12π√(LC) = 1 / (2 × 3.14 × √(90.3 × 0.258 × 10^-6)) = 33 Hz;
Test current: I = 2πfCU_test = 2π × 33 × 0.258 × 10^-6 × 52 × 10³ = 2.78 A.
2. 10kV/500mm2 cable with a length of 1.5km undergoes an AC withstand voltage test. The capacitance is ≤ 0.692uF. The test frequency is 30 – 300Hz, the test voltage is 22kV, and the test duration is 5 minutes.
If three sections of reactor are connected in parallel, then: L = 86/3 = 28.7H,
Then:
Test frequency: f = 1 / (2π√LC) = 1 / (2 × 3.14 × √28.7 × 0.692 × 10^-6) = 35.7 Hz;
Test current: I = 2πfCU_test = 2π x 35.7 x 0.692 x 10^-6 x 22 x 10³ = 3.41 A.
3. The AC withstand test for the 35kV/60000kVA main transformer, with an capacitance of ≤ 0.02uF, is conducted at a frequency of 45-65Hz, with the test voltage not exceeding 68kV, and the test duration is 1 minute.
If four sections of reactor are connected in series (with mutual inductance coefficient of 1.2), then: L = 86 × 4 × 1.2 = 412.8 H.
Then:
Test frequency: f = 1 / (2π√LC) = 1 / (2 × 3.14 × √412.8 × 0.02 × 10^-6) = 55 Hz;
Test current: I = 2πfCU_test = 2 × 55 × 0.02 × 10^-6 × 68 × 10³ = 0.47 A.
4. The AC withstand voltage test for a 10kV/25MW thermal power generator, with an capacitance of ≤ 0.15uF, is conducted at a frequency of 45-65Hz, with the test voltage not exceeding 23kV, and the test duration is 1 minute.
If two sections of the reactor are connected in parallel, then: L = 86 / 2 = 43 H, and a compensation capacitor of 30 kV / 5000 pF should be configured.
Then:
Test frequency: f = 1 / (2π√LC) = 1 / (2 × 3.14 × √43 × 0.2 × 10^-6) = 54 Hz
Test current: I = 2πfCU_test = 2π × 54 × 0.02 × 10^-6 × 23 × 10³ = 1.56 A.
The capacity of the series resonance withstand voltage test device is set at 162 kVA/108 kV, consisting of four sections of reactors. Each reactor section has a capacity of 40.5 kVA/27 kV/1.5A/86H. The use of reactor series and parallel connections can meet the test requirements for the above-mentioned test samples.
Main technical parameters and functions of the series resonance withstand voltage test device
Rated capacity: 162 kVA;
2. Input power: Single-phase 220V or three-phase 380V voltage, with a frequency of 50Hz;
3. Rated voltage: 27kV; 54kV; 108kV
4. Rated current: 4.5A; 3A; 1.5A;
5. Working frequency: 30 – 300 Hz;
6. Output waveform of the device: Sine wave
7. Waveform distortion rate: The distortion rate of the output voltage waveform is ≤ 1%.
8. Working time: Allowed continuous operation for 60 minutes under rated load; withstand overvoltage of 1.1 times for 1 minute.
9. Temperature Rise: The temperature rise should be no more than 65K after continuous operation for 60 minutes under the rated load.
10. Quality factor: The device’s own Q is greater than or equal to 30 (f = 45Hz);
11. Protection Function: It provides overcurrent, overvoltage protection and protection against the breakdown of the test sample (refer to the section on variable frequency power supply for details);
12. Measurement accuracy: The system has an accuracy of 1.5 grade.
Post time: Apr-10-2026