Motor; Transformer - Maytag MFR Series Service Manual

MOTOR

All MFR washers, that are equipped with
inverter drives, use 3-phase drive motors.
The power for these motors comes directly
from the inverter drive. The inverter converts
the incoming single phase power to 3-phase
power. The power to the motor is not true AC
current; it is pulsed DC current that actually
mimics AC current.
3-phase motors that are inverter driven use
less energy than asynchronous motors,
because the inverter can change the
frequency of the current supplied to the motor
allowing for a slow ramp up speed in spin.
The reversing action of the motor in the wash
cycle is also performed by the inverter drive,
which causes less wear and tear than when
relays accomplished this reversing procedure.
Reversing this 3-phase motor requires
reversing two of the incoming motor power
legs. This is accomplished by the inverter
drive and helps to explain why it is very
important to mark the wire positions while they
are still on the motor, when the motor is going
to be replaced. This wire positioning is just as
critical at the output terminals of the inverter
drive.

TRanSFORMeR

The control board step-up transformer is used
only in the MFR18 - 25. This transformer
provides 230 volts for the control board.
This washer is powered by 120 volts 60Hz
only. Wires are marked for the primary 120
volts and secondary 230 volts. The insulated
connectors are on the red and black wires on
the 120 volt primary side and they are marked
0 and 120. On the 230 volt secondary side,
the wire colors are gray and white.
nOTe: Supplying 220-240 volts to the MFR18
or 25 washer will severely damage the control
board.
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