Induction Motor
A 2 pole induction motor operates with a 0.10 slip, and a line voltage frequency of 60 Hz. What is the motor shaft's rotational speed (rpm)?
Expand Hint
The synchronous speed for ac motors is:
$$$n_s=120*f/p$$$
where
$$f$$
is the line voltage frequency in Hz, and
$$p$$
is the number of poles.
Hint 2
The slip for an induction motor is:
$$$slip=\frac{(n_s-n)}{n_s}$$$
where
$$n$$
is the rotational speed.
The synchronous speed for ac motors is:
$$$n_s=120*f/p$$$
where
$$f$$
is the line voltage frequency in Hz, and
$$p$$
is the number of poles.
For a 2 pole motor operating on 60 Hz voltage:
$$$n_s=120*60/2=3,600\:rpm$$$
The slip for an induction motor is:
$$$slip=\frac{(n_s-n)}{n_s}$$$
where
$$n$$
is the rotational speed.
$$$0.10=\frac{(3,600rpm-n)}{3,600rpm}$$$
Solving for
$$n$$
:
$$$n=3,600rpm-0.1(3,600rpm)=3,600rpm-360rpm=3,240\:rpm$$$
3,240 rpm
Time Analysis
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