UOM Converter
Motor speed & slip
Synchronous speed from frequency and poles, slip from the nameplate speed, and the same motor on the other frequency.
Try an example
Convert from
4-pole motor at 60 Hz, 1,750 r/min nameplate
On 50 Hz
How it's calculated
- Synchronous speed = 120 × frequency ÷ poles.
- Slip = (synchronous − nameplate) ÷ synchronous.
- Poles from a nameplate: the pole count whose synchronous speed is just above it.
A 60 Hz motor on 50 Hz runs about 17% slower and its voltage must drop in proportion (e.g. 460 V → 380 V); check the nameplate before using a motor on the other frequency.
Worked examples
4-pole motor at 60 Hz, 1,750 r/min nameplate
- Synchronous speed: 1,800 r/min
- Poles: 4
- Slip: 2.78%
- Synchronous speed: 1,500 r/min
- Running speed, about: 1,458 r/min
2-pole motor at 60 Hz, 3,550 r/min nameplate
- Synchronous speed: 3,600 r/min
- Poles: 2
- Slip: 1.39%
- Synchronous speed: 3,000 r/min
- Running speed, about: 2,958 r/min
6-pole motor at 60 Hz
- Synchronous speed: 1,200 r/min
- Synchronous speed: 1,000 r/min
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