Page 89 - CITS - Electrician - Trade Practical
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ELECTRICIAN - CITS



           EXERCISE 37 : To start & run DC series, shunt &

                                      compound motors

            Objectives

           At the end of this exercise you shall be able to:
           •  check the terminals & connections of DC series, shunt and compound motors
           •  Start & run the series, shunt and compound motors with DC starters
           •  apply the mechanical load on DC motors and measure the speed & torque.

           Requirements

           Tools/Equipments/Instruments
           •  Combination Plier 165mm,                         •  Ammeter MC, 20 A               -1 No.
                                                                                    1/2
              insulated                     -1 No.             •  Multi meter Digital, 3  digit      -1 No.
           •  Screw Driver 150mm, insulated    -1 No.          •  Rheostat 700 Ω, 5A             -1 No.
           •  Neon Tester 75mm, 500 V       -1 No.             •  Tacho meter 3000 RPM           -1 No.
           •  Electrician knife insulated     -1 No.           •  DC power supply unit 30 A, 250 V  -1 No.
           •  DC series motor with mechanical                  Materials/Components
              load arrangement 3 HP, 250 V   -1 set.
           •  DC compound motor with mechanical                •  Test lamp 60 W, 230 V           -1 No.
              load arrangement 3 HP, 250 V   -1 set.           •  DPST switch 250 V, 32 A         -1 sheet.
           •  DC starter-2 point, 3 point, 3 point             •  Connecting wire 2.5 sq.mm       - as reqd.
              3 HP, 250 V                   -Each 1 No.        •  Cotton waste / cloth            - as reqd.
           •  Voltmeter MC, 250 V             -1 No.
           •  Ammeter MC, 5 A                 -1 No.

            Procedure


           TASK 1 : Check the terminals of DC Motors
           1  Check & read the specifications of DC series, shunt and compound motors
           2  Check and identify motor terminals, measure the resistance of armature & field coils.
           3  Draw the connection diagram of start & run of DC series, shunt and compound motors.


           TASK 2 : Start & run of DC Series motor
           1  Make the connections of DC series motor with 2 point starter as per circuit diagram.
           2  Apply the mechanical load on the motor (Never start DC series motor without load).

           3  Check the connections & connect the motor to DC power supply unit through DPST switch.
           4  Start the motor by operating DC 2 point starter.
           5  Record the starting & running current, voltage and speed of the motor.
           6  Reduce the load slightly and check the speed of motor by tacho meter. (Note- Never reduce the mechanical
              load fully when motor is running)
           7  Switch OFF the supply and disconnect the motor.













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