Starting and Reversing speed of a DC shunt motor

Objectives:

  • 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.

Theory:

Circuit Diagram:

Apparatus Used:

 Procedure:

  • 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.

Experimental Data:

 Precaution:

  • 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.

 Conclusion:

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