Explainer video · TEMISA

High voltage (hipot) test on a 4,160 V motor: 2 × 4,160 + 1,000 = 9,320 V

Short answer

The high voltage (hipot) test is the acceptance test for new winding insulation. A new motor gets twice its rated voltage plus 1,000 volts for one minute: for 4,160 V that's 9,320 V. It doesn't damage it; it proves the insulation withstands switching and starting spikes. A winding that has already run gets a lower voltage.

Key points

New 4,160 V motor: tested at 9,320 V (2 × rated + 1,000 V).
In service, insulation sees spikes from switching and starts.
A weak spot fails in the shop, not in the plant.
The full test is for new windings.
Used windings get a lower test voltage.

Transcript

Why does a new 4,160-volt motor get 9,320 volts and not burn? It's not punishment, it's the acceptance test. In service, its insulation takes spikes from switching and starts, so it has to withstand much more than its normal voltage. Like testing a bridge with more weight than it will carry. The formula is twice rated voltage plus 1,000 volts: for 4,160, that's 9,320. If there's a weak spot, it fails in the shop, not in your plant. But careful, that full test is for new windings; one that has already run gets a lower voltage. So it's not damaging it, it's proving it. Did yours get a high voltage test? Comment TEST and we'll tell you what to check.

Frequently asked questions

Where does 9,320 V come from?

Twice rated voltage plus 1,000 V: 8,320 + 1,000 = 9,320 V. NEMA MG 1 sets it as a one-minute routine test.

Does the hipot test damage the motor?

No, at the right level it is an acceptance test that proves the insulation's margin.

Is the same voltage used on a used motor?

No, windings that have run get a lower voltage. Email ventas@temisa.mx.

Video with images and narration generated with AI.

See the service: Electric motor testing

Request a quotation by email: ventas@temisa.mx. Phone: +52 33 3614 2460.