# Power factor of series and parallel connected inductances

Discussion in 'Physics' started by b.shahvir, Mar 11, 2011.

1. ### b.shahvir Thread Starter Active Member

Jan 6, 2009
444
0
Hi Guys,

What will be the effect on 'Power Factor' of the power supply system under the following conditions:-

1) If I were to connect several inductors in ‘parallel’ with the power supply system.

2) If I were to connect several inductors in ‘series’ with the power supply system.

Does system Power Factor differ if two inductances are first connected in parallel and then in series with each other?

Thanks & Regards,
Shahvir

2. ### DrNick Active Member

Dec 13, 2006
110
2
The power factor is a measure of the phase angle between voltage and current. An inductor can not have an instant change in current and thus, the current drawn from a voltage source by an inductor will lag the voltage. Inductors in parallel will always have an inductance of less than the samllest of the two. Inductors in series sum.

If you put an inductive load on a power system this will cause the power factor to decrease, assuming you have a resistive load as well. If you only have an inductive load the power factor is zero, regardless if they are in series or parallel.

If you have a resistive load and shunt it with an inductor, the smaller the inductor, the larger the reactive current, and thus you will have a lower power factor.

In short: if you have a resistive load the parallel inductors will show a lower power factor than the series inductors assuming you are using the same inductors for both situations.

Lastly, Inductive loads are undesireable usually as they only cause reactive power to be drawn from the source which increases REAL power loss due to the fact that a current is flowing that is not contributing to the real power flow.

3. ### b.shahvir Thread Starter Active Member

Jan 6, 2009
444
0
Thanks. But I didn't quite get the above statement. The overall reactive current will be large and hence power factor will be low if the resistive load is shunted by larger value of inductance.

Also, if I put the same inductor in series with the resistive load, will the PF be greater or lower than in the above case?

Regards,
Shahvir