Power Factor Correction Capacitors - FAQ's

Posted on October 19th, 2016 by vapro

1. What is power factor and why is it important?

Simply stated, power factor is the percentage of consumed power(KW) versus supplied power(KVA). This is important because a low power factor can waste energy, result in inefficient use of electrical power, and often result in higher energy bills. For a more detailed description of power factor click here."What is Power Factor?"

2. How do I know if Power Factor Correction Capacitors will benefit me?

Power Factor Correction Capacitors will improve the energy efficiency of any electrical system, but a reduction in your power bill is only available where a power company charges a power factor penalty. Typically the penalty takes the form of a KVA Demand charge. Steelman will be happy to help you determine if you are paying a power factor penalty. Contact Steelman

3. What is the difference between fixed and automatic Power Factor Correction Capacitors?

There are two types of Power Factor Correction Capacitors: Fixed and Automatic. Automatic capacitors are also known as switched capacitors. Automatic capacitors vary the amount of correction (KVAR) supplied to an electrical system, while fixed capacitors supply a constant amount of correction (KVAR). Automatic capacitors are made up of banks that are switched off and on by a microprocessor controller based on the plant electrical load at any given time. Automatic capacitors are installed at the main incoming power source, while fixed capacitors are generally installed at individual motor loads throughout a plant. For more information visit our selection guide.

4. How do I choose the correct amount of correction for my application?

There are different ways to arrive at the correct amount of KVAR for a given application depending on the information available to you. The IEEE provides standard tables that allow you to choose a KVAR rating for individual motors based on horsepower and RPM rating. Additionally, some motor manufacturers recommend a maximum KVAR rating. Also, the required KVAR can be calculated if you have the following information: Current power factor, desired power factor, and total KW input. For more detailed information, see the "KVAR Application Guide."

5. Which are better, Fixed or Automatic Power Factor Correction Capacitors?

The answer to this varies with each installation. If you have just a limited number of motors that need correction, it would be advisable to put a fixed capacitor at each motor. If you have a large plant with varying loads and numerous motors, an automatic capacitor may be better. Other factors to consider are maintenance and "down-time". A fixed capacitor requires less maintenance and if the unit goes down, you have not lost all of your correction abilities. If you need to replace or work on an automatic capacitor, it may require taking the whole plant down or losing all of your correcting ability for a length of time. Additionally, capacitors cannot be directly connected to some equipment. As you can see there are many factors to consider when choosing fixed or automatic capacitors. Steelman will gladly help you with this decision or visit our selection guide.

6. If I decide to install Power Factor Correction Capacitors, what will my payback time be?

For customers that are paying a penalty, we find that the payback time is generally one year. It can be as little as six months or as much as two years. This depends on the billing structure of your utility. Steelman can help you calculate a specific payback time for your application.

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