Dhanalakshmi Srinivasan Institute of Technology, Samayapuram, Trichy.
1. The motor field rheostat should be kept in minimum resistance position.
2. The alternator field should be kept open throughout the experiment.
3. The direction of rotation due to prime mover and due to the alternator run as the
motor should be same.
4. Initially all the switches are kept open.
1. Connections are given as per the circuit diagram and confirm that the alternator filed
is in open condition.
2. Give the supply by closing the DPST switch.
3. Using the three point starter start the motor to run at the synchronous speed by
varying the motor field rheostat.
4. Apply 20% to 30% of the rated voltage to the armature of the alternator by adjusting
5. To obtain the slip and maximum oscillations of pointers, the speed is reduced slightly
lesser than the synchronous speed.
6. Note down the maximum current, minimum current, maximum voltage and minimum
voltage. Find out the direct and quadrature axis impedance (Zd,Zq).
a. To find Zd and Zq :
b. To predetermine % Regulation:
i. Powerfactor Vs Percentage Regulation
Thus the percentage regulation of the given three phase alternator is predetermined using