Model T20551
Magnetic Switch Instruction Sheet
MAGNETIC
SWITCH
ASSEMBLY
Contactor
SHENDIAN
MA-30
(220V Coil)
Thermal
Overload Relay
SHENDIAN
RA-30
(22-34A)
IMPORTANT: This magnetic switch toggles a motor ON and OFF, and helps
provide thermal overload protection for the motor if operating temperature
gradually increases due to heavy work loads. The thermal overload relay inside
is not designed to cut power in the event of a sudden motor overload or stall.
To help protect a motor from this type of overload, this magnetic switch MUST be connected to a properly sized
power supply circuit with a correct fuse or circuit breaker.
OPERATION: The green push button switch allows current to go to the magnetic coil which pulls the contactor
closed. Main current now passes through the thermal overload relay and then to the motor. This relay monitors
motor current draw. If the motor begins to overheat, this relay breaks the magnetic field, which opens the
contactor and cuts current to the motor. The red push button breaks the magnetic field, which opens the
contactor and disconnects the current to the motor.
Electrocution or fire could occur if this switch is
not installed by a qualified electrician!
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