Partial Discharge (PD) Testing of Inverter-Driven Motors

Inverter-driven motors used in EVs and other applications are subject to momentary high voltages caused by switching operation.
Continued partial discharges in windings over an extended period of time can cause the insulation to degrade, leading to serious accidents (such as fire) due to short-circuits or insulation breakdowns.
Motor quality and safety can be improved by detecting the causes for breakdown and deterioration of insulation. Achieve this by adding a partial discharge test to the usual hipot test, thereby preventing products and parts with latent defects from being shipped.

Measurement Example

     

Detect a variety of latent defects with two types of IEC-compliant partial discharge testing

AC partial discharge testing
IEC 60270 & IEC 60034-27-1 compliant: Check for internal discharge and surface discharge caused by insufficient space between windings and by foreign material.
Surge partial discharge testing
IEC 61934 & IEC 60034-27-5 compliant: Check a DUT’s durability against large voltage surges (quick-rising spikes associated with inverter driving).

Product configuration proposed by Hioki

The ST4200 is a partial discharge tester that can perform both AC partial discharge (AC PD) testing and surge partial discharge (surge PD) testing, which is also known as impulse PD testing.
The test voltage is applied from an impulse winding tester (a surge tester) or withstand voltage tester (a hipot tester), and a PD sensor detects partial discharges. Integration of the PD sensor into the High Voltage Multiplexer SW2001 facilitates development of streamlined testing systems.
        

Instruments Used

High Voltage Multiplexer ST4200

1. Partial Discharge DetectorST4200

Guarantees safety by two types of tests in accordance with IEC partial discharge standards

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Automatic Insulation/Withstanding HiTester 3153

2. Automatic Insulation/Withstanding HiTester3153

・AC high voltage source

・PWM method generates accurate test voltage independent of supply voltage

・AC withstand voltage test: Max. 5 kV

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Impulse Winding Tester ST4030A

3. Impulse Winding TesterST4030A

・Surge generator

・Applied voltage: 100 V to 4200 V
(resolution set in 10 V steps)

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High Voltage Multiplexer SW2001

4. High Voltage MultiplexerSW2001

Integrates all of the motor stator inspection

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5. Partial Discharge SensorST9200

For AC partial discharge detection
Specify when ordering; built into the SW2001

6. Partial Discharge SensorST9201

For surge partial discharge detection
Specify when ordering; built into the SW2001

Basic Knowledge

What is Partial Discharge in an Inverter-Driven Motor?

6 Electrical Tests in the Electric Motor Manufacturing Process

Improving Motor Testing Lines with Economical Partial Discharge Testing

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