Page 87 - CITS - Electrician - Trade Practical
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ELECTRICIAN - CITS



           EXERCISE 36 : To identify the parts of DC Motor


            Objectives

           At the end of this exercise you shall be able to:
           •  dismantle and re-assemble of DC Motor
           •  identify the different parts of DC Motor
           •  measure the resistance of field coils & armature
           •  check & identify the terminals of DC Motor.

           Requirements

           Tools/Equipments/Instruments

           •  Combination Plier 165mm,                         •  Bearing puller                 -1 No.
              insulated                        -1 No.          •  Rubber mallet 0.5 kg            -1 No.
           •  Screw Driver set 150mm, 5 blades    -1 No.       •  Old DC compound Motor 250 V DC -1 No.
                                                                                    1/2
           •  Neon Tester 75mm, 500 V          -1No.           •  Multi meter Digital, 3  digit   -1 No.
           •  Electrician knife insulated      -1 No.          Materials/Components
           •  Spanner set 6 to 32 mm           -1 set.
           •  Allen key set 4 to 8 mm          -1 set.         •  Test lamp 60 W, 230 V           -1 No.
           •  Ball peen hammer                 -1 No.          •  Emery paper                     -1 sheet.
                                                               •  Cotton waste / cloth            - as reqd.

            Procedure

           TASK 1 : Check the name plate details of DC Motor

           1  Clean the given DC motor with cotton waste.
           2  Read the name plate and record the specifications of DC motor.
           3  Place the DC motor on wooden table and make a mark on both sides of end covers & yoke.


            TASK 2 : Dismantling of DC Motor
            1  Unscrew the assembly nut bolts & screws of DC motor with spanner / Allen key.
            2  Remove the both side end covers of motor by gently tapping with mallet.
            3  Disconnect the terminals of field coils and armature.

            4  Carefully remove the carbon brushes from the commutator.
            5  Carefully take out the armature assembly without damaging field coils.


           TASK 3 : Identify the parts of DC Motor and re-assemble
           1  Check & identify the parts of DC Motor, viz- Yoke, Armature, commutator, brush, field coils, pole shoe
           2  Measure the resistance of shunt field coil, series field coil and armature with multi meter.

           3  Check & identify the motor terminals in terminal box.
           4  Reassemble the DC Motor in properly.
           5  Check the motor for proper mechanical assembly, free rotation of shaft.
           6  Clean the machine and keep it in proper place.
           Safety precautions
           1  Use proper tools for dismantling & assembling the DC motor.





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