Power Factor Correction Capacitors

Willett Manufacturing Ltd. offers a full line of Power Factor Correction Capacitors designed to update existing power systems. Power Factor Correction Capacitors offer an inexpensive means of reducing demand and increasing efficiency of a motor load. The Willett Power Factor Capacitor reduces high power losses by dropping current throughout the plant, and in so doing, can even increase plant load. The ongoing savings far surpass the initial cost of a Willett Power Factor Correction Capacitor.

An ever-growing need for power factor improvement for low voltage, small and medium power installations led to the production of the Power Factor Improvement Capacitor. These capacitors feature the most advanced technological developments in the industry. Willett highly recommends the use of this product.

Our line is rated 480 VAC, 60 HZ, single and three phase 2 through 100 KVAR. The Capacitor is completely waterproof per CSA standards. In any plant situation, the capacitor output should average an average power factor of 0.90 – 0.95.

Technical Information

Low Loss/Self-Healing Plastic Dielectric:

The Willett Power Factor Capacitor uses a Self-Healing Plastic Dielectric. This consists of sheets of polypropylene film. The foils are formed by a very thin layer of aluminum deposited directly on the plastic film by evaporation under vacuum. In the event of subsidence of the dielectric, the consequent electric arc produces evaporation of a small area of the metal and thus restores the insulation. This property known as self- healing allows many subsidences of the dielectric with interruption of the service while the capacitor’s properties remain unaltered. In fact the metal surface involved in healing is so limited that the variation in capacity is entirely negligible. The polypropylene film is not damaged by the process of self-healing so that capacitors have a very long life and high reliability.

The polypropylene film has very low losses, the value of which is about one-tenth that of the conventional oil-paper capacitor. In fact, the value of the tangent of the loss angle at 60 HZ and rated voltage is approximately 0.5 W/kvar. The low losses, with all other things being equal, lead to much lower capacitor operating temperature, with a consequent reduction in aging through heat. Where as paper-dielectric capacitors require fitting precautions, none are required with the Willett Power Factor Improvement Capacitor.


Capacitors are impregnated with a dielectric fluid, which does not create even the slightest amount of pollution. Conventional paper capacitors are impregnated with fluids containing biphenyl polycholride (PCB). PCB’s are prohibited due to the danger of environmental pollution. They are not biodegradable, and pose a serious health risk.


Capacitors are fitted with discharge resistors that will reduce voltage to less than 50 volts one minute after disconnection from the power supply line, as laid down in IES Standards. There is no need to provide discharge devices when fitting.

Additional Advantages

No further need to pay a penalty to the electrical power supplier for a low power factor value. This represents substantial savings.
Reduction in plant current upstream of the capacitors. This allows you to increase the load without the need to install new transformers or conductors with bigger cross-sections.
Lower voltage drop in transformers and conductors, given the same load. You can increase the load and still obtain satisfactory voltage values.