Contactor - Maytag MFR Series Service Manual

The contactor is an electromagnetic relay that
provides a break in the current supplied to
the inverter drive when no power to the motor
is called for. This current interrupter allows
the power or current to continue flowing to
other devices and controls such as the drain
valve motor, the water inlet valves, the control
board, and the chemical supply relays while
the inverter and the drive motor are isolated
from the circuitry.
The contactor has a 208-240 volt power
supply that is connected to its coil, which is
the electromagnet. This coil is only energized
by the control board when the inverter is to
be powered up. The inverter is powered up
during the Configuration process as well as in
wash cycles when the control board is calling
for the drive motor to turn the wash basket.

COnTaCTOR

The contacts of the relay have a supply side
that is directly wired to the incoming power
supply, and a working side that is wired to the
inverter. This is all single phase 208-240 volt.
Three phase is only supplied on the output
side of the inverter to the drive motor.
When 220-240 volt power is supplied to the
contactor coil from a relay on the control
board, the coil energizes and magnetizes the
armature. This armature, once magnetized
pulls the "E" shaped iron bar into the
magnetized field with enough force to
overcome the reset spring. When the iron
bar is fully pulled into the magnetic field the
secondary or working contacts are bridged
to the primary contacts or input power supply
of the contactor. This closure of primary to
secondary contacts allows the supply voltage
to be sent to the inverter input. The inverter
then reconfigures the 208-240 volt single
phase power supply to 3 phase 240 volt to
power the drive motor.
NOTE: This 3 phase power cannot be
checked with a standard Volt-Ohm Meter, it
requires a specialized Oscilloscope to read
this 3 phase power.
3-15