ASCT/EEE/LAB/BEE-01 (1-PH Active & Reactive Power)

EXPERIMENT NO. - 01

AIM: - To Measure Active & Reactive Power of a Single-Phase A.C. Circuit &

Hence Measure Power Factor & Impedance.

INSTRUMENTS REQUIRED:

S. No. Instruments Range Quantity1. Ammeter 0-10A 12. Voltmeter 0-300V 23. Wattmeter 5A/300V 24. 1-phase load -- 1

THEORY:

The power which is actually consumed or utilized in a.c. circuit is called True power

or active power or real power &is consumed only in resistance, inductor &capacitors don’t

consumed any active power in a circuit. In a half cycle what so ever power is received from

the sources by inductor and capacitor, same amount of power is returned to the source in the

next half cycle. Therefore, power in inductor & capacitors that flows back & forth & reacts

upon itself is known as reactive power.

True Power or Active Power = (Voltage)* (Current In Phase with voltage) =VIcosΦ watts

Reactive Power or Quadrature Power =(Voltage) *(Current 90* Out Of Phase With

Voltage) = VIsinΦ VAR

CIRCUIT DIAGRAM:-

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ASCT/EEE/LAB/BEE-01 (1-PH Active & Reactive Power)

PROCEDURE:-

01. Keeping Load Constant & Varying the Voltage1. Connect the instruments, autotransformer & load as shown in circuit diagram.

2. Switch o0n the supply & adjust the autotransformer to a suitable voltage.

3. By keeping load at affixed position vary the voltage by autotransformer & take

down the various reading of voltmeter, ammeter& wattmeter

02. Keeping Voltage Constant & Varying the Load.

1. Repeat the first two steps of procedure 01

2. By keeping adjusted voltage constant vary the load step by step

3. Take the readings of voltmeter, ammeter & wattmeter for the given load at each

load.

OBSERVATION TABLE No.1:

S. No. V(volt)

I(ampere)

W(watts)

cosΦ

1.

2.

3.

4.

OBSERVATION TABLE No.2:

S. No. Load I(amperes)

V(volts)

W(WATTS)

X (ohms)

1.

2.

3.

4.

5.

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ASCT/EEE/LAB/BEE-01 (1-PH Active & Reactive Power)

CALCULATION:-

MEASUREMENT OF POWER FACTOR:From wattmeter reading:

W = VIcosΦ watts

Therefore; cosΦ = W/VI lag

MEASUREMENT OF IMPEDANCE:Total Impedance, Z = V/I ΩResistance, R = ZcosΦInductive Reactance, X = √(Z2 – R2)

RESULT:-1. Power varies as square of applied voltage; & for a given load power factor is constant.

2. Power varies, as a load is changed & power factor at different load is different.

3. The impedance of the given load for observation 01 is _______________

4. The power factor of the given load for observation 01 is _____________

PRECAUTIONS:-1. Keep the autotransformer to zero position at the time of starting of experiment.

2. Use the instruments of the given range.

3. Make the connections tight.

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