Variable frequency drive applications guide
Traditionally, fans and pumps have been designed to be capable of handling the maximum demand of the system in which they are installed. However, quite often the actual demand can vary and it can be much lower than the original design capacity. These situations have been corrected in the past through additions of outlet dampers to fans or throttling valves to pumps. While these can be effective and simple controls they severely affect the efficiency of the system. Variable frequency (speed) is the most efficient means of capacity control. The most cost effective method of achieving variable speed capacity control is using AC adjustable frequency drives. AC adjustable frequency controls convert any fixed speed AC motor into an adjustable speed device. Adjusting the speed of a motor, by controlling the frequency of the AC power to that motor, reduces its horsepower requirements. According to pump and fan laws, capacity is proportional to speed while horsepower is proportional to the cube of the speed. Therefore, by reducing the speed of an AC motor by 20 percent the horsepower requirement is reduced by nearly 50 percent. Reduced speed through variable frequency control allows for flexibility of meeting changing weather and comfort requirements without operating costly equipment at full capacity.
- Research Organization:
- Urban Consortium for Technology Initiatives (United States). Energy Task Force; Public Technology, Inc., Washington, DC (United States); Phoenix Public Works Dept., AZ (United States). Energy Conservation Div.
- Sponsoring Organization:
- USDOE; USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG02-90CE27504
- OSTI ID:
- 6997225
- Report Number(s):
- DOE/CE/27504-9; ON: DE93005615
- Country of Publication:
- United States
- Language:
- English
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