New NO-ARC Relay Technology Extends Life of Controllers


St. Louis, MO - A new technology developed by Watlow engineers extends the life of relays incorporated in Watlow's temperature and power switching controllers used in heating applications requiring a high volume of cycles. Electromechanical relay technology has been the same for many years, as has the electrical arcing that can shorten the life of electromechanical relays. But this engineering "fact of life" has changed thanks to Watlow's new technology, called NO-ARC.

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 greatly extents 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 four million cycles.

"When the control signal is provided to the product to turn the relays on, NO-ARC technology energizes a circuit that is in parallel with the contacts to carry the load so the contacts do not have to," says Watlow product manager, Jim Hentges. "Then, we do the same thing when the relay is expected to open or turn off."

NO-ARC technology is superior to alternative technologies for many reasons including that it can handle high current without a large heat sink. Eliminating the need for a heat sink further reduces ownership costs and the number of components required for operation. Watlow is the first heater manufacturer to introduce this new technology.

Any application that requires millions of cycles will see value in arc suppression technology. "Many industries are constantly seeking ways to reduce costs, so building in an arc suppression circuit extends the life of relays, reducing the need for product replacement and potential manufacturing downtime," Hentges says.

Watlow products that incorporate NO-ARC technology include:

E-SAFE(TM) II Hybrid Power Switch

E-SAFE(TM) II provides reliable and accurate power switching in a mercury-free product. E-SAFE II offers a switching life of millions of cycles at 35 amperes at a high ambient temperature rating of 70°C (158°F) providing superior performance. NO-ARC relay technology not only allows it to switch millions of cycles but also decreases noise and increases temperature accuracy.

EZ-ZONE® PM Integrated Controller

The EZ-ZONE® PM is a 1/32 or 1/16 DIN panel mount controller offering options to reduce the complexity and cost of a control loop. The EZ-ZONE PM controller can be configured as a PID controller, over/under limit controller or these functions can be combined into one integrated controller. Using NO-ARC relay technology the EZ-ZONE PM is able to offer 15 ampere load capacity and offers over two million cycles at rated load (maximum 240V~(ac), five second minimum cycle time).

EHG® SL10 Process Controller and Safety Limit

EHG® SL10 is an integrated/adjustable, agency recognized safety limit (UL®1998), temperature controller and heater all in one system. Its compact design, inherent reliability and integrated limit functions make this system a tremendous value. EHG SL10 incorporates a NO-ARC relay as the process output switching device, making it more reliable than traditional thermostats and thermofuses. This controller will typically provide four to five million cycles at 10 amp rating.

About Watlow
Since the company's founding in 1922, Watlow has brought its thermal expertise to numerous applications, including semiconductor, analytical, medical, clinical, plastics processing, foodservice equipment, packaging, aerospace and others. Headquartered in St. Louis, Missouri, Watlow is the largest custom designer and manufacturer of industrial heaters, sensors, controllers and software with offices and manufacturing facilities around the world.

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