Abstract: An electric switch is provided with a support frame at which several key switch elements are individually clipped on. An actuating front piece is attached at the support frame, which is mounted at a front plate of a switching cabinet or the like. A transmission apparatus with a compression spring is provided between a pressure pin of the actuating front piece and a ram of the key switching elements. The compression spring, the ram and the pressure pin are disposed in an inner space of the support frame receiving the key switching elements. The transmission apparatus provides several individual thrust journals which are resting in the base body and which are moved against the force of the individually coordinated overthrow springs for actuating the key switch elements against the ram.

Abstract: The surveillance signal apparatus is preferably provided a signal lamp, as an illuminated switch or as an illuminated key. It comprises a casing with electrical and electronic connections and with an apparatus heat disengageably disposed at the casing. The apparatus head comprises a signal part provided with electric voltage and preferably an illuminating element. A voltage limiter and a current limiter are disposed in an explosion-proof and pressure tight encapsulated space of the casing and they are electrically predisposed to the signal part in the apparatus head via a feed part. The apparatus head with the signal part and the feed part are formed by the output of the voltage limiter and by the output of the current limiter as an explosion protection self safety unit.

Abstract: A surveillance device is provided for a container filled with a fluid or the like and it includes an electrical resistance wire for temperature control and a hygroscopic insulator for control of humidity. For this purpose, an electrical conductor wire is disposed substantially in parallel to the resistance wire in its longitudinal direction, which forms together with the resistance wire and the hygroscopic insulator a single unit multifunctional temperature-humidity measurement cable. At least two essentially parallel running wire conductor strands are provided for a potential-free and mutually noninterfering measurement. The hygroscopic insulator is disposed between the wire conductor strands. The cable sensor can be employed in power and steam plants and in nuclear installations.