Automatic impulse testing of motor stators using high-voltage relays


In the case of a 3-phase stator, impulse tests are carried out between each phase combination: U-V, V-W, W-U, V-U, W-V, and U-W.
Consequently, manufacturers work to automate such tests by using relays to switch test circuits.
However, when test voltages exceed 1500 V, it becomes impossible to use standard relays.
As a result, impulse testing between stator phases is carried out by means of manual measurement or manual switches.


The High Voltage Scanner 3930 can be used as a measurement circuit switch.
The 3930 incorporates lead relays that can be switched at voltages of up to 5 kV DC or 5 kV AC.
Sequence Maker (an Excel add-in) can be used to create and execute automatic test sequences.
The 3930 can be controlled using I/O from a PLC or similar device.
In this test, Hioki used a PHC-D08 (PATLITE Corporation), which supports contact control from a PC. 

Measurement scene

• Sequence Maker switches between the High Voltage Scanner 3930’s output channels.
• After switching, Sequence Maker controls the ST4030A to conduct an impulse test.
• Each test consists of three demagnetization pulses, 10 test pulses, and a pass/fail judgment.
• The test results and data are received by Sequence Maker.

Measurement data

Fig. 7 illustrates the effects of wiring length.
The “STANDARD WAVE” shown in the top graph was created by the ST4030A alone.
The “PULSE1 WAVE” depicts the waveform for this test (which adds the 3930 and wiring to increase the wiring length by 3.3 m).
The bottom graph overlays data obtained by testing the same point 10 times in this test.
Although the longer wiring has an effect, it has no impact on the reproducibility of results for that point.


·This application describes a method for automatically performing impulse testing between phases (U-V, V-W, W-U, V-U, W-V, and U-W).
·Automatic testing can be performed on production lines by replacing the control and I/O (contact I/O) functionality provided by Sequence Maker with a PLC.

Application precautions:
Sequence Maker can be downloaded free of charge.
Sequence Maker can also be downloaded from the URL provided in the User Manual.
Please contact a Hioki salesperson if you require a sample program.

Contact Metrology Lab by Hioki for application questions and test requests.

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