An integrated safety limit, temperature controller and heater, Watlow’s EHG SL10 incorporates a No-Arc relay as the process-output switching device.

In an effort to extend the life of relays incorporated into temperature and power-switching controllers used in heating applications and requiring a high volume of cycles, engineers at St. Louis-based Watlow have developed a new technology. Electromechanical relay technology has been the same for many years, as has the electrical arcing that can shorten the life of these relays. But this may be changing with the advent of Watlow’s No-Arc technology.

A No-Arc relay is a mechanical relay with arc suppression provided through the use of smart electronics. The technology reduces the amount of arcing across the relay contacts and extends the life of the relay. Relays without No-Arc typically have a life cycle of about 100,000 cycles at rated amperage, while a No-Arc relay will have a life of more than 4 million cycles, according to Watlow.

The technology can handle high current without a large heat sink. Eliminating the need for a heat sink reduces ownership costs and the number of components needed for operation, says the company.