This type of electrical switch is widely used for switching power since 1835. It is operated by an electromagnet to open or close the contact. The relay receives a low voltage input signal from the temperature controller. This low voltage signal creates an electromagnetic field which attracts a mechanically linked contact. Returning to the relaxed state is done by a spring.
An ideal cycle time for an electro-mechanical relay is 25 – 120 seconds. The on / off life cycle is often less than 250’000 times. This type of relays is not built for constant high speed switching which is required for radiant heaters like quartz lamps or air heating. For these applications we recommend solid state relays or silicon controlled rectifiers (SCR) which do not arc.