- To become familiar with the starting and reversing the speed of a D.C. shunt motor.
- To become familiar with the starting of a D.C. shunt motor using 3-point starter.
- The circuit is connected as shown in the circuit diagram.
- The DC supply is switched on with minimum resistance in the field circuit and the starting handle is moved to first position slowly.
- As soon as the arm makes contact with first stud of the 3 point starter, the motor stars running.
- The armature current increases rapidly and settles to a steady value.
- The armature current, armature voltage and field current at the instant of starting are noted.
- Gradually all resistances are cut by further moving the arm to the right slowly.
- When the arm reaches the run position, all the resistances are bypassed and starting arm would be attached with electromagnet.
- The armature current, armature voltage and field current and speed are noted when values settle to a steady value.
- The direction of rotation of motor is observed at different connection mentioned in table-2.
- The supply is switched off and starting arm comes to off position automatically.
- Voltage across armature should not be applied without applying voltage to the field winding of a D.C. motor.
- All connections are to be tightly connected.