# Effects on power factor

1. Apr 2, 2009

### b.shahvir

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.

Thanks & Regards,
Shahvir

2. Apr 4, 2009

series

3. Apr 4, 2009

### b.shahvir

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.

Thanks & Regards,
Shahvir

4. Apr 4, 2009

### tiny-tim

Hi Shahvir!

Show us what you think, and your reasons, and then we'll know how to help!

5. Apr 5, 2009

### b.shahvir

Ok, as we know that the overall inductance of a circuit increases if one were to connect several inductances in series. Similarly, the overall circuit inductance decreases if several inductances are connected in parallel. I believe that overall system Power Factor varies with system inductance, i.e., if system inductance increases then overall Power Factor worsens (reduces). Similarly, if system inductance decreases then overall Power factor improves (increases). This is my understanding….I might be wrong.

Hence going by this logic, the increase in no. of inductive loads ( say induction motors, gas lamps with chokes, etc.) connected in parallel to a building’s electrical system, will improve the overall system Power Factor, in my opinion. Then what role will Power Factor improving equipment like capacitor banks or APFC panels be left to play? They would be rendered redundant! This is what is still unclear to me.

Thanks & Regards,
Shahvir

6. Apr 6, 2009

7. Apr 9, 2009

8. Apr 9, 2009

9. Apr 9, 2009

### Staff: Mentor

How about you tell us what you know about power factor, and maybe even give us a pointer to a good web page that describes power factor. Then put your question in context (homework, coursework, industrial building power entry design, etc.). Then we might be able to offer some thoughts....

10. Apr 9, 2009

### Bob S

It is well known, and used for many industrial applications, that large capacitors in parallel (shunt) with the power lines can correct an inductive power factor (PF). I worked at a place that had to change the number of capacitors depending on the inductive load and on the outside temperature (which changed the capacitance of the large outside capacitors in the cap bank) to keep within the PF limits required by the electric utility. I also worked at a facility that had several large salient-pole synchronous motors (~ 500 HP ea) to correct the PF (the motors were part of large motor generator sets). Off-load synchronous motors are "synchronous capacitors". I do not know of any facility that uses inductances to correct the power factor, however.

11. Apr 9, 2009

### Naty1

Shavir..you are correct....

http://en.wikipedia.org/wiki/Power_factor

where it explains how energy is stored in reactive loads, either inductors or capacitors, and their is a phase difference introduced whereby the voltage and current do not peak together...such a power delivery is less efficient than with a pure resistive load....and the power peaks with neither voltage nor current...

12. Apr 9, 2009

### MATLABdude

Let's reduce this question down a little... Imagine you just have two inductors of the same inductance.

a) What's the total inductance when they're in series?
b) What's the total inductance when they're in parallel?

Now, what's the power factor of a purely inductive load?

With the above, you'll realize that this question is too unconstrained to be properly answered (as is given).

13. Apr 10, 2009

### b.shahvir

Last edited by a moderator: Apr 24, 2017
14. Apr 10, 2009

### b.shahvir

Thanx for your reply. I have posted my thoughts in the same thread duplicated in the Classical Physics section. I humbly request you to refer to the same.

This is a thought which popped up in my head. It is not part of any project or course work.

Kind Regards,
Shahvir

15. Apr 10, 2009

### Staff: Mentor

Dupllicate threads are not allowed. I've merged the two threads into one here in EE.

16. Apr 11, 2009

### b.shahvir

Thanx but then i did be happy if i get some response!

17. Apr 13, 2009

### m.s.j

Dear Shahvir,

In first post, you talk about power factor of power supply and in continue you talk about power factor of power system. Please note there are two different conceptions.
Usually power factor is defined for electrical loads and the ratio of X/R is defined for power sources.

For calculation of load power factor you can use following formulas:

COS (F) = P/ (P2+Q2)1/2

P = V2/R
Q = V2/X
V= constant voltage
X = Reactance of loads (2 x 3.14 x f x L)

When you decrease the circuit load inductance (Q increasing), you front the decreasing of load power factor.

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18. Apr 13, 2009

### b.shahvir

Thanx for your reply. Actually, I'm referring to the impact of variation in value of load inductances on total power factor of the electrical installation.

Regards,
Shahvir