Page 87 - CITS - Electrician - Trade Practical

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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