Industrial and commercial users of electrical power, often have a large number of motor loads and other loads that consume large amounts of reactive power (typically inductive), and are often assessed a surcharge for the additional power losses those loads produce on the (utility-owned) transmission/distribution lines that supply the customer’s facilities.
In order to avoid that surcharge, these customers often elect to install compensating (often called power factor correction) reactances, which cancel out all or part of the reactive component of their loads, thus making their aggregate load primarily resistive in nature, which minimizes the current required to operate those loads.
Power factor correction capacitors are used to compensate for loads with a significant lagging (inductive) power factor. Depending on the costs, they are typically distributed throughout the distribution system, including at motor loads, at sub-stations and at the main distribution that feed the customers electrical system. Each location has its advantages and disadvantages, depending on the desired result of their application.
The following table shows the typical un-improved power factor at various types of industries. A common billing structure used by electrical utilities is commonly called the 90% method. In this method rates are applied to either 100% of the kW reading for the month or 90% of the kVA reading, whichever is greatest. The last column shows the amount of Demand cost reduction that can be realized when the facilities power factor is increased to above the 90% threshold at which surcharges begin to accure.
Typical Un-improved Power Factor in Industries
| By Industry | Power Factor | Potential Demand
Cost reduction by % |
| Auto Parts | 75-80 | 10-15 |
| Brewery | 76-80 | 10-14 |
| Cement | 80-85 | 5-15 |
| Chemical | 65-75 | 15-25 |
| Coal Mine | 65-80 | 10-25 |
| Clothing | 35-60 | 30-55 |
| Electroplating | 65-70 | 20-25 |
| Foundry | 75-80 | 10-15 |
| Forge | 70-80 | 10-20 |
| Hospital | 75-80 | 10-15 |
| Machine Mfg | 60-65 | 25-30 |
| Metalworking | 65-70 | 20-25 |
| Office Bldg | 80-90 | 0-10 |
| Oil-field Pumping | 40-60 | 30-50 |
| Paint Mfg | 55-65 | 25-35 |
| Plastic | 75-80 | 10-55 |
| Stamping | 60-70 | 20-30 |
| Steelworks | 65-80 | 10-25 |
| Textile | 65-75 | 15-25 |
| Tool, Die, Jig | 60-65 | 25-30 |
Fig.1 Ref: IEEE Std 141-1993
Note: Each utility has its own billing structure.
It is important to check with your utility to find out
what structure you have to follow for your facility.
Typical Un-improved Power Factor by Operation
| By Operation | Power Factor |
| Air compressor: | |
| - External motors | 75-80 |
| - Hemetic motors | 50-80 |
| Metal working: | |
| - Arc welding | 35-60 |
- Arc welding with
standard capacitors | 40-60 |
| - Resistance welding | 40-60 |
| Machining | 40-65 |
| Melting: | |
| - Arc furnace | 75-90 |
- Inductance furnace
60Hz | 100 |
| Stamping: | |
| - Standard speed | 60-70 |
| - High speed | 45-60 |
| Spraying | 60-65 |
| Weaving: | |
| - Individual drive | 60 |
| - Multiple drive | 70 |
| Brind | 70-75 |
Fig.2 Ref: IEEE Std 141-1993
With over 30 years experience specializing in power factor & power quality correction Cos Phi can help determine if your facility needs power factor correction and the best methods for its application.
Cos Phi is also one of Canada's premier power factor correction bank manufacturers which allows us to ensure you get the correction equpment that is perfectly suited to your facility.
If you would like to investigate whether you require power factor correction, download, complete and send us the site information document below and we'll contact you or
contact us to arrange a meeting and we'll complete it for you.
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