OPEN CIRCUIT CHARACTERISTICS OF SELF EXCITED DC SHUNT GENERATOR - Code

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Monday, April 4, 2011

OPEN CIRCUIT CHARACTERISTICS OF SELF EXCITED DC SHUNT GENERATOR


OPEN CIRCUIT CHARACTERISTICS OF SELF EXCITED
DC SHUNT GENERATOR

AIM:
To obtain open circuit characteristics of self excited DC shunt generator and to find its critical resistance.

APPARATUS REQUIRED:
S.No.
Apparatus
Range
Type
Quantity
1
Ammeter
(0-1)A
MC
1
2
Voltmeter
(0-300)V
MC
1
3
Rheostats
1250W, 0.8A
Wire Wound
2
4
SPST Switch
-
-
1
5
Tachometer
(0-1500)rpm
Digital
1
6
Connecting Wires
2.5sq.mm.
Copper
Few

PRECAUTIONS:
  1. The field rheostat of motor should be in minimum resistance position at the time of starting and stopping the machine.
  2. The field rheostat of generator should be in maximum resistance position at the time of starting and stopping the machine.
  3. SPST switch is kept open during starting and stopping.



PROCEDURE:
  1. Connections are made as per the circuit diagram.
  2. After checking minimum position of motor field rheostat, maximum position of generator field rheostat, DPST switch is closed and starting resistance is gradually removed.
  3. By adjusting the field rheostat, the motor is brought to rated speed.
  4. Voltmeter and ammeter readings are taken when the SPST switch is kept open.
  5.  After closing the SPST switch, by varying the generator field rheostat, voltmeter and ammeter readings are taken.
  6. After bringing the generator rheostat to maximum position, field rheostat of motor to minimum position, SPST switch is opened and DPST switch is opened.



TABULAR COLUMN:

S.No.
Field Current
If (Amps)
Armature Voltage
Eo (Volts)

















MODEL GRAPH:



RESULT:
Thus open circuit characteristics of self excited DC shunt generator are obtained and its critical resistance is determined.

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