## Synchronous Speed

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

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__**Hint**

**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).

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__**Hint 2**

**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