Power Factor What is it? Power factor is when electricity is being used inefficiently, mainly because of the use of motors. This wastes power and money and increases greenhouse gas emissions. emissions A detailed explanation is given below. How does it work? Appliances such uch as toasters and kettles use power efficiently but most motors in refrigerators, air conditioners, pressure pumps,, large motors in industry, etc, are inefficient users of power power. How does it become poor? The power triangle (shown below) is useful useful in explaining power factor and how poor power factor comes about. Motors and all appliances/equipment use electricity along ong the bottom of the triangle (shown in green) – this achieves the work that needs to be done e.g. cooling the inside of a refrigerator refrige rator. But motors, when working inefficiently, draw energy heading upwards from the base of the triangle (shown in red) red). This inefficient use of energy adds to the real power and increases the apparent power (shown in yellow) yellow). This will cost commercial and industrial electricity users on o their power bill and adds to unnecessary greenhouse ga gases because more power is used to achieve the same effective work. work Most homes only get charged for real power, power so there is no financial incentive for home owners to improve their poor power factor. But most businesses get get charged for what is called a “peak demand” for the apparent power. This is the highest apparent power that is recorded by the meter for the monthly billing period period. Poor power factor can be corrected by adding capacitors to the circuit by what is called power factor correction equipment (see over). Capacitors can remove the wasted energy and cause the apparent power to equal the real power (power factor is then unity or 1.0 which is ideal). This will minimise the “peak demand” apparent power charged by the power company. The only other way to reduce the peak demand charge is to reduce you usage by not turning things on o or using equipment with better star ratings ratings. Total energy usage longer than it needs to be (apparent apparent power) power Motors cause wasted energy here Capacitors can be connected and subtract and correct poor power factor Power factor = Cos of angle All appliances use power here (real power) In summary - poor power factor is mainly caused by the use of electric motors and can be easily corrected by the use of capacitors. These capacitors are installed in a cabinet with a controller (see photo over) that governs how many of capacitors are connected to the electricity supply at any one time. Cooling fans On/Off Switch Low Voltage Power Factor Correction Unit Electronic Controller Capacitors Inductors that help protect the capacitors Contactors that turn capacitors on or off Cost Justification for Installing Power Factor Correction Equipment The installation of power factor correction equipment is justified: When a “peak demand” charge is imposed by the electricity network supply company; To reduce greenhouse gas emissions (becoming increasingly important). Home owners are generally charged for real power (kilowatt hours [kWh’s]) and would not see any reduction in their electricity charge if they improved their power factor, unless they have larger generators or pump equipment. Maintenance of Power Factor Correction Equipment Once installed, your power factor correction equipment will only need to be monitored and maintained with an annual check up. Contact Electrical Consulting and Training Pty Ltd – your power factor correction installation, monitoring and maintenance specialists. 1 Barnard St Gladstone NSW 2440 Australia Ph 02 6567 5181 Fax 02 6567 5182 www.elect.com.au