# Leo's HVAC Tip: Power Factor

June 2, 2005
 Email / Print / Reprints / More / Text Size+
Power Factor - Power factor is the ratio of real power to apparent power.

Real Power - Real power is the actual power being used in a circuit.

Apparent Power - Apparent power is the power calculated for that circuit based upon measuring only volts and amps with a volt-ammeter.

To understand power factor, you need to know that: The power (watts) available in an alternating current (AC) circuit is equal to volts times amps. A volt-ammeter measures the voltage and the amperage in an AC circuit.

If the voltage and amperage in a circuit peak at the same instant, they are said to be in sync and the power factor (PF) is 1.00. This means that the real power and apparent power are the same.

However, in electrical circuits with coils (such as induction motors, solenoids, and transformers) inductive reactance causes amperage to lag behind voltage. They are out of sync.

If the volts and amps do not reach their maximum at the same instant, the available power (volts x amps) is less than the measured power. This is because the volt-ammeter measures the mean value of volts and of amps and does not show whether they peak at the same instant.

Thus, the real power (the available power) is less than the apparent power (the measured power) and the power factor is less than 1.00.

Adapted from Basic Electricity, LAMA Books.

Publication date: 06/06/2005

## Image Galleries

### 2014 Energy Efficiency Forum

Highlights from the 25th annual Energy Efficiency Forum in Washington, D.C.

## Podcasts

Jeremy Begley, home-performance specialist and Web and social media manager with National Heating and Air Conditioning Co. in Cincinnati discusses how and why you should add home-performance philosophies to your contracting repertoire. Posted on Sept. 12.

More Podcasts

## 2014 September 15

Check out the weekly edition of The NEWS today!

### Venting R-22

The NEWS reported that a man received prison time for venting R-22. Should EPA step up enforcement?
View Results Poll Archive

### HVACR INDUSTRY STORE

2014 National Plumbing & HVAC Estimator

Every plumbing and HVAC estimator can use the cost estimates in this practical manual!

More Products

### Clear Seas Research

 With access to over one million professionals and more than 60 industry-specific publications, Clear Seas Research offers relevant insights from those who know your industry best. Let us customize a market research solution that exceeds your marketing goals.