With the MTLx523V interface, an on/off device in a hazardous area can
be controlled by a voltage signal in the safe area. It is suitable for driving
loads such as solenoids. Line fault detection (LFD), which operates
irrespective of the output state, is signalled by a safe-area solid-state
switch which energises if a field line is open or short–circuited. Earth
fault detection can be provided by connecting an MTL4220 earth
leakage detector to terminal 3.