One single phase wattmeter operating on 230V and 5A for 5 hours makes 1940 revolutions. Meter constant in revolutions is 400. What is the power factor of the land?
A. 1
B. 0.84
C. 0.73
D. 0.65
Answer: Option B
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@Smiths saji thank for your explanation
kWh consumed=230 x 5 x 5 =5.750 kWh
meter constant= 400 rev/kWh
rev for 5 hours = 1940
kWh= rev/ meter constant= rev/rev/kWh =1940/400=4.85 kWh
Actual power factor=4.85/5.75=0.843
Energy consumed = 230 × 5 × 5 = 5750 Wh
= 5.57 kWh Revolution constant = 400 rev/kWh
∴ kWh =
1940
= 4.8
400
Power factor =
4.8
= 0.8
Aparrent power (kvah)= 230×5x5/1000=5.750
Active power (KWh)= 1940/400=4.85
P.f (Cos €) =KWh/Kvah= 4.85/5.75=0.843
kWh consumed=230 x 5 x 5 =5.750 kWh
meter constant= 400 rev/kWh
rev for 5 hours = 1940
kWh= rev/ meter constant= rev/rev/kWh =1940/400=4.85 kWh
Actual power factor=4.85/5.75=0.843
GIVEN V=230V, I=5A& T=5 Hours
meter constant =400, revolution=1940
energy (E)=REVOLUTION/ METER CONSTANT
energy (E)=1940/400 =4.85 KWH = 4850WH
Energy consumed(E) = 230v *5A * 5 hours = 5.750 kwh = 5750 WH
POWER FACTOR = 4850/5750 =0.843
Energy consumed = 230v *5A * 5 hours = 5.750 kwh
Revolution constant =400/kwh so =1940/400= 4.85
P.F = 4.85/5.750= 0.84
@hari
please explain this question sir.