Synchronous motor


These motors run synchronous (without slippage) with the electricity frequency (Hertz).

They are commonly used in elevators and compressors, but seldom used in pumping systems.

The most common reasons for specifying synchronous motors:

  • Their cost with excitor and control can be less than that other AC motors if the horsepower rating is equal to or greater than twice the rpm.
  • To get higher efficiency
  • To obtain power factor correction
  • To obtain special starting characteristics.
  • To obtain a constant speed.
  • Combinations of special high or low torques and low inrush current can be furnished without appreciably affecting the operating characteristics at rated speed.

Most pumps use lower costĀ induction, or “squirrel cage” motors where synchronous speed is not that important.