Hello Bruce, Your motor starter has three poles for use with 3 phase
motors. Since your motor is single phase, you should only use two of
the poles on the motor starter for the red and black wires. Black motor
lead to T1 and red motor lead to T2. From the power source, connect
black to L1 and red to L2. The white wire is the neutral conductor and
can carry a bit more current than the other two wires. That's probably
why the starter is tripping. The white wire from the motor should be
bugged directly to the white neutral conductor from your power source.
L3 and T3 are not used.
If the motor starter still trips, there might be a problem with the
starting capacitor on the motor or possibly the centrifugal starting
switch if it has one of those. If you have a clamp-on current probe,
measure how much current is flowing in each of the black and red motor
leads. The numbers should be about equal and less than the full load
amperes (FLA) rating on the motor nameplate.
This type of starter is not usually required for single phase motors.
It's designed for protecting 3 phase motors in the event of the loss of
one of the three phases from the power source. When this happens,
a 3 phase motor will stall and emit a loud hum while heating up rapidly.
In this case, more current will flow in the two remaining hot phases.
This is when the heaters do their job and open the circuit.
A simple two-pole contactor would be more appropriate for controlling
the motor you have. If you go that route, make sure the nameplate says
the motor has built-in thermal overload protection. Most single phase
motors have this feature.
Larry Doe
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