Detail Mauell MR 21
Relay MR 21 Just like the MR 11, the MR 21 relay is used for the indication of danger and alarm situations and operational states. Ist miniature size ( 39 x 46 mm ground surface) makes it suitable to be combined in large numbers so that the entire relay assembly can be used for alarm and status signalling in control rooms, control panels and mimic diagrams. Function Unlike the MR 11 relay, the MR 21 relay is fully automatic. It has no manual reset button and no NO/ NC changeover facility. Depending on the preset contact mode ( N/ O or N/ C operation) the relay picks up either at energization or at deenergization. The contacts operate and the mechanical indicator flag is set. Upon return to normal of the fault situation the indicator flag is automatically acknowledged and the contacts return to their normal position.