Electrical Power Switching

The temperature controller transmits an electrical signal to the power controller, which then adjusts the power of the heater. The main electrical power switching devices are:

While the electromechanical relay is the most economic investment, the constant heat up and cool down of the resistance wire in the heating elements will diminish heater life with repeated use. To avoid arching, an electromechanical relay should not be activated more than every 20 seconds. A mercury relay can be activated every 6 seconds or so, while a solid-state relay can be activated every second.

For applications like infrared heating, electric air heaters or for other low mass heating elements, a solid state relay (SSR) or a silicone-controlled rectifier (SCR) should be used. This zero cross or phase fired power controllers allow optimal control of the heating process.

Please see the other sections of the Delta T website for more information or contact us with any additional questions.

Electromechanical relay

solid state relay with heatsink