SPEED CONTROL OF DC SHUNT MOTOR

SPEED CONTROL OF DC SHUNT MOTOR Pre Lab Questions: 1.

What are the factors controlling motor speed?

2.

Name the various speed control methods of shunt motor

3.

Define stalling current.

4.

Why is the armature rheostat kept at maximum position and field rheostat at minimum position?

5.

In which method of speed control speed can be varied about rated speed?

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SPEED CONTROL OF DC SHUNT MOTOR NAME:

REG NO:

EX NO:

DATE:

Aim: To control the speed of the given DC shunt motor by a. Field control method b. Armature control method

Apparatus Required: S.No.

Apparatus

Range

Type

Quantity

1 2 3 4 5

Precautions: 1. Field Rheostat should be kept in the minimum resistance position at the time of starting and stopping the motor. 2. Armature Rheostat should be kept in the maximum resistance position at the time of starting and stopping the motor.

Procedure: 1. Connections are made as per the circuit diagram. 2. After checking the maximum position of armature rheostat and minimum position of field rheostat, DPST switch is closed (i) Armature Control: 1. The field current is kept constant and the armature voltage is varied in steps with the help of armature rheostat and the corresponding speeds are noted down 2. The above procedure is repeated for different values of field current. 2

(ii) Field Control: 1. Supply is switched ‘ON’ and the motor is started 2. The armature voltage is kept constant and the field current is varied in steps and the corresponding speeds are noted. 3. The above procedure is repeated for different values of armature voltage Circuit diagram:

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Tabular Column: Armature Control Method Ir1 = 0.8A Sl.No.

V Volts

Ir2 = 0.7A

N Rpm

V Volts

1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

4

N Rpm

Field Control Method Sl.No.

If A

N Rpm

If A

1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

Model Graphs:

5

N Rpm

Model calculation:

Result:

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Post Lab Questions: 1.

What are the advantages of field control method?

2.

What are merits of rheostatic control method?

3.

Mention some advanced methods of speed control of DC shunt motor.

4.

On what factors does the speed depend on?

Mode of assessment In lab performance (10) Pre lab questions (5) Post lab questions (5) Total (20) Faculty Signature

7

Marks obtained