Calibration and Testing of Single-Phase Energy Meter

Our aim here is to calibrate the given Single-Phase Energy Meter using a precession Wattmeter and stopwatch using or employing phantom loading. The main apparatus required for conducting this practical experiment include:

• Single-Phase Induction type Energy Meter – 240V (5-10)A
• Wattmeter 300V/10A UPF
• Phase Shifting Transformer 440V/440, 500VA
• Single-Phase Variac – 240V / (0-270)V

Procedure for calibration and testing of Single-Phase Energy Meter:-

1. Give the connections as per the circuit diagram above.
2. Apply 220V A.C to the pressure coil circuit by means of phase shifting transformer.
3. Apply a load of 2 Amps by switching on the load.
4. Note down the reading of two meters in a given period of time, say 2 minutes.
5. Find out the percentage error at this load.
6. Now rotate the rotor of phase shifting transformer so that the working power factor (p.f) of the meter is varied.
7. For this power factor repeat steps 4 and 5.
8. Now increase the load current in suitable steps and repeat the steps 4,5,6 and tabulate the results. The expected example results are given in the table below:
   
   

   S.No	Current I(A)	Power Factor	Wattmeter (w)x2	Time (T) in Hours	Measured Power (Whr)	% error
   1.	5	UPF	1160	0.0105	12.18	23.87
   2.	5	0.8 lead	720	0.0180	12.96	19
   3.	5	0.8 lag	1120	0.0105	11.76	26.5
   4.	4	unity	920	0.0136	12.512	21.8
   5.	4	0.8 lead	560	0.0227	12.712	20.55
   6.	4	0.8 lag	880	0.0133	11.704	26.85
   7.	3	unity	680	0.0177	12.036	24.775
   8.	0.8 lead	440	0.0297	13.068	13.068	18.32
   9.	3	0.8 lag	680	0.0180	12.24	23.5

   

Thus we’ve done the testing and calibration of a given Single-Phase energy meter.