Relay coupler RKS2-5.24

Whenever levels and power have to be matched, as is the case for low switching frequencies, electromechanical relays are the preferred choice as interface components between peripheral process devices and the control logic. In principle, electromechanical relays are divided into two main categories, monostable and bistable.
Monostable AC or DC-relays return their swich contacts to a non-operative state independently after coil current has been switched off.
Bistable relays, on the other hand, leave their switch contacts in the last switched position after the energising current has been interrupted.