When using a 3 wire control circuit to control a magnetic motor starter the part that will open the control circuit when an overload occurs will be?
The part that opens the circuit is the overload blocks that are
situated below the magnetic starter and before the motor load. The
latest addition to the electrical code book states that the "hot"
wire goes through the overload contacts first before feeding the 3
wire control system. With the supply voltage in this position the
whole circuit becomes de-energized when the motor load trips the
circuit.
The old standard practice on a 3 wire control system, the
neutral was connected to the overload relay contacts. When the
overload relay tripped it opened the neutral of the coil circuit
and the starter dropped out