Munich – Schaltbau, located in Munich, has introduced a new high-voltage signalling relay. The ZH842 H is a result of the development of the company’s signalling technology. Compared to its direct predecessor it has even more features.


The ZH842 H is designed to signal what kind of high voltage is being applied to the train line, a cable running the length of the train. For this purpose a potential-free relay contact is made as long as there is an UIC550-compliant supply voltage at the input terminals that exceeds the threshold voltage. Thus it is possible to energise battery-powered electric equipment which is operated, for the sake of conserving battery power, only when high voltage is applied.

A special advantage of this new high-voltage signalling relay is that it works irrespective of the battery supply. This implies that no leakage currents, which greatly contribute to battery discharge, are passed on by the device.

The input voltage range to UIC550 is 0.7kVAC to 5kVAC, and 1kVDC to 5kVDC, respectively. The relay contact is maintained in its working position at a threshold voltage of >670VAC and >610VDC respectively. Its maximum DC switching capacity is 19W at 24V, 31W at 31V, 27W at 110 V and 50W at 150V.

The ZH842 H is identical in design to its forerunner model. It is integrated in a metal housing the lower portion of which forms the mounting bracket. Sealed to IP20, its outward dimensions are 160mm x 185mm x 38mm (length x depth x height). The temperature range is -40°C up to +85°C.

The ZH842 H is EN 50155 type tested, including for insulation, EMC, shock and vibration.