Thermal Issues in Power Factor Systems

Regardless of whether harmonic distortion is present or not, Power Factor Correction (PFC) systems generate heat. Although harmonic blocking reactors produce the majority of this heat, capacitors also produce a significant amount of heat, as well as heating when dealing with harmonic currents. In total, this is approximately 5-7 Watts per kVAr. This means a single 400kVAr cabinet has the equivalent of a 2.5kW heater running continuously. Therefore, all power factor boards require forced air cooling.

In the past, harmonic blocking reactors were omitted from designs when harmonic distortion was low or absent, and forced air cooling was not usually required. As long as harmonic currents are kept low, the capacitors are capable of withstanding their own heat under acceptable conditions. As harmonic currents increased, reactors were added in order to protect the capacitors. However, air cooling was not always included to counter excess heat produced by reactors, causing the capacitors and unit to overheat. 

Another consideration is the capacitor life expectancy. Site reports show that the capacitor life is proportional to the average operating temperature, so the cooler the cabinet and capacitors run, the longer they last. Taking into consideration the cooling systems between reactors and other equipment, such as capacitors, is an important aspect in the design of a system. Reactors will operate at temperatures 40-70⁰C hotter than capacitors; therefore, it is essential to ensure that cooling air does not pass over a hot reactor, then flow over a cooler capacitor and heat it up. kVAr Solutions power factor trays and systems are designed to thermally isolate the reactors and have a separate cooling system from the rest of the equipment.

All Power factor correction systems require forced air cooling to extend the life and counteract the heat generated by the capacitors and reactors. Our designs at kVAr Solutions focus on heat dissipation, and we have developed innovative thermal designs for our systems. This system includes thermal separation, targeted air flow, and over-temperature alarms. This design has been proven to achieve maximum cooling throughout the cabinet, prolonging the system's life.