The illustrated, animated schematic to the right displays a Three Phase Reversing Motor Starter with stop, foward and reverse buttons.
A Reversing Motor Starter is two starters in one with two coils and one overload block.
There are two sets of power contacts; one for forward and one for reverse.
The rotation of a three phase motor can be reversed be reversing any two phases.
The connections are;
|Load Side Forward||T1||T2||T3|
|Load Side Reverse||T3||T2||T1|
Both sides have a set of normally open and normally closed contacts for control.
The normally closed forward contact connects directly to the reversing coil.The normally closed reversing contact connects directly to the forward coil.
Control the coils through the normally closed contacts. This means only one can run at a time. If forward is running its normally closed contact is open and no power can be connected to the reversing coil.
Reversing Motor Starters have mechanical interlocks to prevent a phase to phase short. If both coils are energized the mechanical interlock will prevent one contact from closing since this condition will overheat the coil and burn it out. By simply running through the normally closed contact from one side to get to the coil of the other side, coil damage is avoided.