08-05-2012, 04:26 PM
SWINBURNE’S TEST
51355420-LAB-MANUAL-FOR-E-E-CS.pdf (Size: 523.09 KB / Downloads: 35)
FORMULAE
1. Armature resistance (Ra) = 1.6 × RDC in Ohms.
Where,
RDC – Resistance of the Armature coil, when it is energized by DC supply.
2. Constant loss (WCO ) = (V Io-Iao2Ra) in Watts..
Where V = Terminal Voltage in Volts
Io = No Load Current in Amps
Iao = No Load Armature Current. in Amps
3. Armature Current (Ia) = (IL ± If ) in Amps.
Where, + is used for Generator,
- is used for Motor.
4. Copper loss (WCU ) = Ia2Ra in Watts.
5. Total loss = Constant loss + Copper loss in Watts
6. Input power for motor / Output power for generator = V IL in Watts
Where, IL is Load current in Amps
7. Output power for motor = Input power + losses
Input power for Generator = Output power - losses
8. Percentage of Efficiency = (Output power/Input power) × 100
PRECAUTION
• The motor field rheostat should be kept at minimum resistance position.
• The motor should be at no load condition through out the experiment.
• The motor should be run in anticlockwise direction.
PROCEDURE
• Connections are given as per the circuit diagram.
• By using the three point starter the motor is started to run at the rated speed.
• The meter readings are noted at no load condition.
• The motor is switched off using the DPIC switch.
• After that the Armature resistive test is conducted as per the circuit diagram and the voltage
and current are noted for various resistive loads.
• After the observation of readings the load is released gradually.