An induction motor system operable in a wet environment comprises an
induction motor and an apparatus for controlling the speed of the motor.
The motor is adapted to be coupled to an AC source for supplying an AC
signal. The motor includes a rotor having rotor laminations. The reflected
rotor resistance over reflected rotor reactance ratio of the motor is
adjusted to be greater than one. The controlling apparatus includes a
switching device, user controls, controller means and isolation means. The
switching device is connected in series with the motor and is operative in
either a high impedance state wherein significant current flow through the
motor is prevented or a low impedance state wherein current flow through
the motor is substantially undisturbed. The user controls provide motor
speed input signals. The controller means receives the motor speed input
signals from the user controls, and switches the switching device between
its low and high impedance states in a predetermined sequence for inducing
a phase angle delay in the AC signal. The isolation means electrically
isolates the controller means from the AC source and includes coupling
means for optically coupling the switching device to the controller means.