Used when emergency functions are required such as in the case of a power cut. A 18 Vdc power supply is used with this adaptor and the necessary batteries to provide the necessary current and voltage for the system, (batteries not included with the adapter). 2 x 12V standard acid lead batteries with the necessary amperage must be connected. They are mainly used in video door entry systems which use the Fermax ADS, MDS and 4+N Systems. It has two operating led indicators: - GREEN Led on: Normal Operation. - RED Led on: Emergency Operation. Used when emergency functions are required for a system. It has a DIN 10 rail-mountable format to facilitate its installation on the interior of electrical panels, or alternatively it can be screwed directly onto the wall. It is constructed from VO self-extinguishing material.