Explainer video · TEMISA

Electric motor starting current: why it pulls 6 to 7 times rated and doesn't burn

Short answer

At start, with the rotor still, the motor behaves like a shorted transformer and can pull 6 to 7 times its rated current. It doesn't burn because that current drops within seconds as it picks up speed. The risk is starting it again and again back to back: heat builds up in the copper. Respect the manufacturer's starts per hour.

Key points

With the rotor still, the motor acts like a shorted transformer.
It can pull 6 to 7 times rated current at start.
Current drops within seconds as speed builds.
Back-to-back starts build heat in the copper.
Respect the manufacturer's starts per hour.

Transcript

Why does a pump motor pull up to 7 times its current at start and not burn up? It's not that it can take anything, it just lasts very little. With the rotor standing still, the motor acts like a shorted transformer. Like running 100 meters all out: you last a few seconds, not all afternoon. It can pull 6 to 7 times its rated current, but it drops within seconds as it picks up speed. But careful, start it again and again back to back, and heat builds up in the copper. Respect the manufacturer's starts per hour. So it's not that it doesn't heat up, it's that you don't give it time. Does yours trip on start? Comment START and we'll tell you what to check.

Frequently asked questions

Why doesn't the motor burn on start?

The high current lasts only seconds and drops as the motor picks up speed.

What happens with repeated starts?

Heat builds up in the copper; respect the manufacturer's starts per hour.

What if the motor trips on start?

Check protection, load and the winding. TEMISA diagnoses and repairs motors; email ventas@temisa.mx.

Video with images and narration generated with AI.

See the service: Electric motor maintenance

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