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The DFS 4 NA – two devices in one housing

Switch off in case of emergency!

Norden, January 2015. In many situations, it is useful, or even specified by standards or installation regulations, for circuits to be equipped with an emergency switch function. The new DFS 4 NA provides an isolating device of this kind and compatible residual current protection together in one unit.

According to DIN VDE 0100-723, both residual current protective devices and isolating devices with remote actuation (usually standard mushroom buttons) must be used at every output in laboratories and training rooms, etc. The new NA switch offers this very connection option.

The technical requirements are clearly defined in order to achieve maximum protective potential. All laboratory equipment must be fitted with this type of device for switch-off in the event of an emergency. An isolating device is also prescribed here, which can disconnect all active conductors including the neutral conductor. Therefore, AC-DC sensitive residual current circuit-breakers with a residual operating current no higher than 30 mA must be used. The Doepke DFS 4 NA combines all of these properties in one device.

Multiple DFS 4 NA residual current circuit-breakers can be operated by a single emergency stop switch if necessary. The status of the emergency stop circuit is indicated via an LED. The integrated auxiliary switch can also be used to forward information about trips. The auxiliary switch is implemented as a changeover contact.

The emergency stop function of the DFS 4 NA is active from a voltage of 50 V, the maximum touch voltage, regardless of whether the device is running in single-phase or three-phase operation. Like all DFS residual current circuit-breakers, the DFS 4 NA has an extremely low dissipation power per pole, meaning it does not trip if there is a power failure.

In addition, the DFS 4 NA meets the requirements of DIN VDE 0100-537. The device as a whole is only half of a module width wider than a standard switch.

Almost all DFS 4 switches, i.e. AC-DC sensitive residual current circuit-breakers of type B, are available with the emergency stop function.