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Monday, April 4, 2011

LOAD TEST ON DC COMPOUND MOTOR


LOAD TEST ON DC COMPOUND MOTOR

AIM:
To conduct load test on DC compound motor and to find its efficiency.

APPARATUS REQUIRED:
S.No.
Apparatus
Range
Type
Quantity
1
Ammeter
(0-20)A
MC
1
2
Voltmeter
(0-300)V
MC
1
3
Rheostat
1250W, 0.8A
Wire Wound
1
4
Tachometer
(0-1500) rpm
Digital
1
5
Connecting Wires
2.5sq.mm.
Copper
Few

PRECAUTIONS:
1.    DC compound motor should be started and stopped under no load condition.
2.    Field rheostat should be kept in the minimum position.
3.    Brake drum should be cooled with water when it is under load.






PROCEDURE:
1.    Connections are made as per the circuit diagram.
2.    After checking the no load condition, and minimum field rheostat position, DPST switch is closed and starter resistance is gradually removed.
3.    The motor is brought to its rated speed by adjusting the field rheostat.
4.    Ammeter, Voltmeter readings, speed and spring balance readings are noted under no load condition.
5.    The load is then added to the motor gradually and for each load, voltmeter, ammeter, spring balance readings and speed of the motor are noted.
6.    The motor is then brought to no load condition and field rheostat to minimum position, then DPST switch is opened.



TABULAR COLUMN:

S.No.
Voltage
V
(Volts)
Current
I
(Amps)
Spring Balance Reading
(S1~ S2)Kg
Speed
N
(rpm)
Torque
T
(Nm)
Output Power
Pm
(Watts)
Input
Power
Pi
(Watts)
Efficiency
h%
S1(Kg)
S2(Kg)












































FORMULAE:
                                                           
        Circumference
 R        =     -------------------     m
                        100 x2p

Torque T = (S1 ~ S2) x R x 9.81 Nm


Input Power Pi = VI Watts

                                    2pNT
Output Power Pm =  ------------  Watts
                                       60

                                    Output Power
Efficiency h %     =  -------------------- x 100%
Input Power




  y3     y2      y1
 
Text Box: Torque T (Nm)Text Box: Speed N (rpm)MODEL GRAPHS:





 









RESULT:
Thus load test on DC compound motor is conducted and its efficiency is determined.

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