Electrical Engineering - RL Circuits - Discussion

Discussion :: RL Circuits - General Questions (Q.No.16)


Which of the following power factors results in less energy loss in an RL circuit?

[A]. 1
[B]. 0.8
[C]. 0.4
[D]. 0.2

Answer: Option D


No answer description available for this question.

Nilesh said: (Aug 11, 2014)  
At low power factor less current flow through circuit. Power loss = I^2 R.

Avanish said: (Nov 19, 2014)  
Power loss would be less at unity power factor not at low power factor.

Shweta said: (Jul 22, 2015)  
I agreed with @Avinash, at zero losses pf is unity.

Shweta said: (Jul 22, 2015)  
I think it would be D, because at unity pf power losses is zero.

Kartik Pawar said: (Oct 4, 2015)  
I think it should be option B because at unity pf current is less so losses will be less. But since unity pf is not possible in RL circuit so pf should be close to unity. So option B.

Vijay said: (Jul 29, 2016)  
Answer d is correct, because at pure resistance power loss is high and power factor would be 1. To less power loss in RL circuit, Power factor should be as low as possible.

Ravi Koshiya said: (Aug 20, 2016)  
Energy losses = I^2 * R, clearly, it's seen then it depends on are.

But, as we talk about R-L circuit, inductor comes into the picture makes energy losses depends on z instead of are only. So, if we increase XL than there will be a decrease in P.F. as well as in current. It's clear that in RL circuit low P.F. Comes with fewer energy losses.

Madan C said: (Sep 4, 2016)  
At zero pf current will be more, so that copper losses increases, the correct answer is unity pf.

Manjunath said: (Nov 27, 2016)  
You are correct @Vijay & @Ravi.

Neeraj Kumar said: (Dec 6, 2017)  
I agree with you @Madan C.

Munish said: (Dec 29, 2017)  
If pf is 1 means unity than their is less current flow in the circuit i.e. less energy consumed.

Deependra Kr said: (Apr 19, 2018)  
loss in RL crt= v^2/(R^2+wL^2)*R.

=> loss proportional to pf.

So, the less value of pf is recommended.

Awais said: (Feb 7, 2019)  
P = VI*pf.

Power is directly proportional to power factor. Therefore for minimum power loss pf should be minimum.

Gokul Bhardwaj said: (Mar 6, 2019)  
Answer D is correct.

If the power factor is very less it means there is a large value of inductance in the circuit. It causes an increase in reactance and a decrease in current. If current decreases then power loss is also decreased for constant resistance. However, the disadvantage of keeping the power factor low is that active power is decreased. Thus to do useful work active power must be increased and power factor must be enhanced.

Ahsan said: (Jan 16, 2020)  
D is correct.

PF= R/Z.

Which means greater PF has greater has greater R consequently greater losses.

Neeraj Kumar said: (Jun 1, 2020)  
Answer D is correct.

Because we know that energy loss means here works reactive Power [VI SIN (θ) ], and in sine function, if we increase the value of θ then the value will be increased, which means here we have to choose the minimum value of Power factor.

Ajit Kumar Yadav said: (Dec 19, 2020)  
Power factor = true power/ apparent power.

Therefore power factor inversely proportional to apparent power.

Therefore to minimise apparent power which consists of reactive power that causes more loss, we have to decrease power factor.

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