Static coupling relays

With the static coupling relays imod and omod, safe (electrical) isolation is achieved by an optocoupler. The signal entering the coupling relay is conditioned in several stages to obtain a suitable low-voltage signal for controlling the actual switching element at the output of the module.

In the process, interference due to stray capacitance, as occurs with cables running in parallel, as well as HF and transient interference (short-term voltage peaks) are largely filtered out. The processed signal is fed to an optocoupler. This consists of a luminescent diode (LED) and a phototransistor. They are used to galvanically isolate the input and output signal. Instead of the switching contact in electromechanical relays, a semiconductor output is used in static relays. In DC output modules this is a transistor, in AC output modules triacs are used.

Their advantages include:

• long service life
• short switching times
• bounce-free, noiseless switching
• low drive power