To protect models fitted with reed switches PBwel offer a range of Diode Protection Units. These protect the reed switch contacts against the effect of inductive loads, such as those caused by tripping relays within the marshalling kiosk or control room, typically used to provide multiple simultaneous switching signals. The protection is achieved by means of a suitably rated diode wired across each load. The diode must be rated with forward current at least as high as the steady load current and connected observing polarity so as to absorb the back e.m.f.