Free Engineering Tool
Insulation testing
Insulation Test Voltage Selector
Pick what you are testing and its rated voltage. Get the DC test voltage to set on your megger, and the band it falls in.
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- Your numbers never leave your device
Inputs
What are you testing?
kV
Disconnect or protect electronic equipment before testing.
Readout
SET-V DC
Rotating machines: IEEE 43-2013
IEEE 43 recommends a DC test voltage based on the winding's rated line voltage. Use the lower end for older or damp insulation, and the upper end for clean, dry, healthy windings.
| Winding rated voltage | Test voltage (DC) |
|---|---|
| Below 1000 V | 500 V |
| 1000 to 2500 V | 500 to 1000 V |
| 2501 to 5000 V | 1000 to 2500 V |
| 5001 to 12000 V | 2500 to 5000 V |
| Above 12000 V | 5000 to 10000 V |
Then judge the result with the Motor Minimum IR check and trend it with the PI and DAR calculator.
Low-voltage installations: IEC 60364-6
| Circuit nominal voltage | Test voltage | Minimum IR |
|---|---|---|
| SELV and PELV | 250 V DC | 0.5 MΩ |
| Up to 500 V, including FELV | 500 V DC | 1.0 MΩ |
| Above 500 V up to 1000 V | 1000 V DC | 1.0 MΩ |
Many national rules (including Indian practice and BS 7671) follow these values. Read the house wiring megger guide for the procedure.
Before you press the test button
- Isolate and lock out the circuit, and confirm it is dead with a proper voltage tester.
- Discharge the winding or cable after the test. Long cables and big windings store dangerous charge.
- Your plant specification may call for a different voltage. Always follow the stricter document.
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