26-02-2013, 10:48 AM
Calibration of Power Factor Meter
Calibration of Power.docx (Size: 12.26 KB / Downloads: 24)
APPARATUS:
•Ammeter 1
•Voltmeter 1
•Wattmeter 1
•Power factor meter 1
•Resistive, Inductive and Capacitive Loads
•Connecting wires
THEORY:
Power factor is defined as the ratio of the average (or active) power to the apparent power
(root-mean-square voltage times rms current) of an alternating-current circuit. Also
known as phase factor.
Power factor meter is an instrument used to indicate whether load currents and voltages
are in time-phase with one another.
The single-phase meter contains a fixed coil that carries the load current, and crossed
coils that are connected to the load voltage. There is no spring to restrain the moving
system, which takes a position to indicate the angle between the current and voltage. The
scale can be marked in degrees or in power factor.
The angle between the currents in the crossed coils is a function of frequency, and
consequently each power-factor meter is designed for a single frequency and will be in
error at all other frequencies.
In this experiment the calibration of power factor meter is done by comparing it with a
standard. Power factor obtained from formula is taken as standard here.
PROCEDURE:
1. Connect the circuit according to circuit diagram.
2. Connect resistive load and switch on the supply.
3. Note corresponding readings of voltmeter, ammeter, wattmeter and power
factor meter.
4. Now connect inductive and capacitive loads respectively and repeat step 3.
5. Calculate power factor of each load using formula.
6. Calculate %age error. Error should not exceed ±6%.