Recent activity in the capacitor industry has helped improve the efficiency and life of this very important component. The newest innovation is a dry A.C. motor-run capacitor that is considered safer and more reliable than the oil-impregnated product that, until now, has been the only type available.

This paper, written to introduce the dry capacitor to the HVAC industry, starts with the history of capacitors, continues with failure modes that are encountered, and then specifies the reliability requirements of HVAC manufacturers.

The dry capacitor has gained UL recognition and acceptance by major HVAC manufacturers. The consensus is that most capacitors of the future will be of the dry type. Development has been slow because of the inability to achieve the higher voltage ranges in dry technology. This problem has been overcome, and dry capacitors are efficient and reliable up to 750 volts A.C. in standard microfarad ranges.