Applied Thermal Systems / Watlow E-SAFE MDR Replacement

Watlow Electric Manufacturing Company has developed a hybrid power switching device known as the E-SAFE^TM Relay, that has successfully bridged the gap between mercury displacement relays (MDR's) and the more expensive solid state relays (SSR's). The E-SAFE Relay outperforms MDR's and has a much higher life expectancy (without the use of mercury). It delivers performance comparable to SSR's, at a much lower cost.
Watlow's E-SAFE Relay implements a patent pending, unique "no-arc" circuit. When the relay is switched, power is removed from its contacts providing many benefits to the user. This technology facilitates a faster cycling than is possible with mechanical relays. By eliminating contact arcing, the relay contact life is increased. The E-SAFE Relay provides customers the benefits of SSR's without the price usually associated with that technology. The E-SAFE Relay also significantly reduces the electrical noise found in other relays.

The UL^® 508 & CE listed E-SAFE Relay is uniquely suited for use in plastics processing such as injection molding, extrusion, thermoforming and blow molding processes since all have very demanding cycles. The E-SAFE Relay has been tested at 30 amps, 240V power, 2-second cycle rate and 50 percent duty cycle, resulting in over 20 million cycles before failure. Comparable mechanical relays performed only 12,000 cycles.

Not only is the E-SAFE Relay a highly reliable power switching product with an extremely long contact life, but the fact that it is mercury free in its design provides additional advantages. Because mercury is a hazardous material, its use is heavily regulated by many organizations including the EPA, OSHA, and the Department Of Transportation. For example, one OSHA regulation requires the conspicuous posting of MSDS sheets in the workplace. Another OSHA regulation requires that if an existing mercury switch fails via a leak of any kind, the entire panel in which it is mounted must be replaced. As a result of these and other regulations, many businesses are opting to use alternative technologies as the costs now outweigh the benefits. Europe has already banned the use of mercury switches and it is likely that the US will follow suit as alternatives such as the E-SAFE Relay become available.

The E-SAFE Relay completely eliminates the metal hazard risk to customers, potential panel replacement costs, as well as the need for special toxic waste disposal procedures. Watlow's E-SAFE Relay can be easily retrofitted in the field and fits the footprint of most 30 to 50 amp MDR's and definite purpose relays. A DIN-rail mounting option will soon be available for use with this product.

Watlow's E-SAFE Relay operates at 208/240 volts (ac). It is a three-pole relay with 120 coil voltage that is available for 20 amp and 40 amp applications. It operates at a maximum of 30 cycles/minute, has a maximum operating ambient temperature of 130°F (55°C) and is for resistive loads only. This version of the E-SAFE Relay is currently being marketed in North America but future models are under development to meet global electrical requirements.