GB/T 4074.21-2018Winding wires test methods—Part 21: Electrical endurance under high frequency voltage impulses (English PDF)

3.1 Bipolar impulse

For voltage pulses, the polarity alternates from positive to negative or from negative to positive.

3.2 Impulse-voltage repetition rate

Regardless of unipolar or bipolar pulses, at the same time interval, the reciprocal of the time between two consecutive complete pulses. [IEC 62068:2013, definition 3.14]

3.5 Peak impulse voltage

The maximum voltage value reached during the unipolar surge voltage period (see Figure 1).

Note: For bipolar pulse voltage, the pulse peak voltage is half of the pulse peak-peak voltage (Upk/pk). The pulse peak-peak voltage (Upk/pk) is as shown in Figure 1.

3.6 Steady-state impulse voltage magnitude

The final value of the impulse voltage (see Figure 1).

4.1 Test principle

For the test conditions and test requirements not specified in this part, they shall be carried out in accordance with the product standard.

4.2 Standard environment for specimen state conditioning and testing

4.2.1 When the test winding wire is removed from the spool, it shall neither withstand tension or unnecessary bending, nor shall it be contaminated by the outside.

5.1 Composition of tester

It shall include the following three parts. test power supply, timing device and hot state tester.

5.2 Test power

Each specimen shall use an independent power supply during the test. The test equipment shall meet the following parameter requirements under load conditions.

5.3 Timing device

Each specimen shall be timed separately. When the tested specimen is short-circuited, the timer stops counting and records the test value.

5.4 Hot state tester

The electric heating oven used for the test shall meet the requirements of GB/T 30435. Room temperature ~ 200 °C, temperature deviation is ± 3 °C.

6.1 Corona-resistant round winding wire

6.1.1 Product types

Corona-resistant enameled round winding wire suitable for conductors which have a nominal diameter greater than 0.250 mm and less than or equal to 1.600 mm as well as the grade-240 aromatic corona-resistant polyimide film wrapped sintered round winding wire.

6.1.2 Specimen preparation

For the grade-240 aromatic corona-resistant polyimide film wrapped sintered round winding wire, prepare specimen according to the provisions of 5.1.2 in GB/T 4074.7-2009.

6.1.3 Specimen screening

6.1.3.1 Grade-240 aromatic corona-resistant polyimide film wrapped sintered round winding wire

6.1.3.2 Corona-resistant enameled round winding wire

For the corona-resistant enameled round winding wire, in order to ensure the uniform performance of the same batch of specimens, all specimens shall be subject to power frequency AC withstanding voltage test screening according to the voltage specified in Table 1, before the high-frequency pulse resistance test. The voltage duration is 1 s.

6.1.4 Test sample

Only the samples that pass the screening of 6.1.3 power frequency AC withstanding voltage test can be subjected to the high frequency pulse test in Chapter 7.

6.2 Flat winding wire

Scope of application. Glass fiber wrapped film wrapped flat winding wire, mica tape wrapped flat winding wire and grade-240 aromatic corona-resistant polyimide film wrapped sintered flat winding wire.

7.1 Corona-resistant enameled round winding wire

7.1.1 Product types

Only suitable for corona-resistant enameled round winding wires which has a paint film thickness of grade 2 and 3.

7.1.2 Main parameters of high frequency impulse voltage resistance

See Table 2 for the test parameters of the corona-resistant enameled round

7.1.3 Test procedure

Prepare specimen according to the provisions of 6.1 and conduct power frequency AC voltage withstanding test.

7.1.4 Test results

Test 5 specimens. Record the test results. Take the minimum value and intermediate values.

7.2 Grade-240 aromatic corona-resistant polyimide film wrapped sintered round and flat winding wire

7.2.1 Main parameters of high-frequency impulse voltage resistance

See Table 4 for test parameters of grade-240 aromatic corona-resistant polyimide film wrapped sintered winding wire's resistance to high-frequency pulse voltage.

7.3 Glass fiber film wrapped flat winding wire and mica tape wrapped flat winding wire

7.3.1 Main parameters of high-frequency pulse voltage resistance

See Table 6 for the test parameters of resistance to high-frequency impulse voltage performance of glass fiber film wrapped flat winding wire and mica tape wrapped flat winding wire.

7.3.2 Test procedure

Prepare specimens according to the provisions of 6.2 and conduct power frequency AC voltage withstanding test.

7.3.3 Test results

Test 5 specimens. Record the test results. Take the minimum value and intermediate values. […]