## Synchronous Speed

If an AC motor has a line frequency of 60 Hz and 4 poles, what is its synchronous speed?

Hint
Synchronous speed is the speed of the magnetic field rotation produced by an induction motor’s stator (stationary part of a rotary system), which is always constant once the hardware is designed (assuming you don’t go to another country with a different electrical supply frequency standard).
Hint 2
The synchronous speed for an AC motor is:
$$n_s=\frac{(60)f}{(p/2)}$$$where $$f$$ is the line voltage frequency, and $$p$$ is the number of magnetic poles. Synchronous speed is the speed of the magnetic field rotation produced by an induction motor’s stator (stationary part of a rotary system), which is always constant once the hardware is designed (assuming you don’t go to another country with a different electrical supply frequency standard). The synchronous speed for an AC motor is: $$n_s=\frac{(60)f}{(p/2)}$$$
where $$f$$ is the line voltage frequency, and $$p$$ is the number of magnetic poles. Note in the equation, multiplying the frequency by 60 converts hertz to rotations per minute (rpm). Thus,
$$n_s=\frac{(60)(60Hz)}{(4/2)}=\frac{3,600}{2}=1,800\: rpm$$\$
1,800 rpm