Page 89 - CITS - Electrician - Trade Practical

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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