Forward/Reverse Motor Operation
Objective: To change the direction a three phase induction machine rotation, two of its phases needs to be exchanged, thus changing the phase sequence form, say RYB to YBR. This can be accomplished by using two contactors, one for the forward or CW rotation and one for the reverse or CCW rotation. The forward and reverse contactors are mechanically interlocked i.e., if one of them is closed the other cannot close. This is done to avoid dead short circuit in case both the contactors closing simultaneously.
Also electrical interlocking could be provided using the contactors control contacts.
COMPONENTS OF POWER CIRCUIT.
Power cct comprises of ;
MCB –for power isolation/circuit isolation
KM1-for forward motion
KM2-for backward motion
O/L-for motor protection.
COMPONENTS OF CONTROL CIRCUIT
MCB-for circuit connection and disconnection
O/L- for motor protection.
START BUTTON (P1)--To give command to the motor for operation in forward motion
START BUTTON (P2)-To give command to the motor for operation in backward motion.
KM1-1 –for holding contact in forward contactor
KM2-1–for holding contact in backward contactor
STOP BTTON(0)- for stopping motor in operation.
L1–indication lamp for forward motion
L2–indication lamp for backward motion
L3-indication lamp for motor tripping due abnormal condition.