Measurement of Voltage, Current, Power and Power Factor in a R-L Series Circuit

Experiment No.: 9

Experiment Name:

Measurement of Voltage, Current, Power and Power Factor in a R-L Series Circuit


To measure voltage, current, power and power factor in a R-L series circuit.


As per shown circuit diagram, we have used a 200 Watt incandescent lamp as resistive load (R) connected in series with a ballast of fluorescent lamp as an inductive load (L) as resistive load.

An MI type ammeter is connected in series with the load to measure the current flowing through it. We have selected the ammeter according to the load current. An MI type voltmeter is connected across the load to measure the voltage across it. To measure the power drawn by the load we have connected a wattmeter. And to measure the load power factor we have used a Power Factor meter. In Wattmeter, the multiplying factor is given by,

In our case, MF= (300×10×1)/1500 = 2. So, we have to multiply 4 with the reading taken from the Wattmeter.

Circuit Diagram:

Observation Table:

Sl. No.Resistance (Ω)Inductance (mH)Voltage (V)Current (A)Power (W)Power Factor (cos φ)
 1.44.5827  228 0.2 25×2 = 50  0.6 lag
 2.44.5 827 1780.220×2 = 40   0.58 lag
3.44.5827 2080.225×2 = 50   0.58 lag

Apparatus Used:

Sl. No.Name of the ApparatusQuantitySpecificationMaker’s Name
 1. Incandescent Lamp as Resistive Load 1 200 W, 250 VPhilips 
 2. Transformer Winding as Inductive Load 1 5kVA, 230/115 V
 3. Voltmeter 1 0-250-500 V,
MI type, Table Top,
 4. Ammeter 1 0 – 5 – 10 A, MI type,
Table Top, Analog
 5. Wattmeter1 0-750-1500-3000 W,
150-300-600 V, 5-10 A,
EDM type
6.Power Factor Meter1 0.5 lag – 1 – 0.5 leadMECO-G
7.Variac1240/0-270 V,
Single phase
8.Clip-on Ammeter10-1000 A ACMetravi


The measured reading of the analog ammeter is too low, so we have to use digital multimeter to measure thee current accurately. The wattage shown in wattmeter is too low, so we have to assumed the value.

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