The door-coupling rotary operating mechanisms consist of a knob, a coupling driver, an extension shaft of 300 mm length (8 mm × 8 mm), a spacer and two metal brackets, into which the MSP is inserted. The door-coupling rotary operating mechanisms are designed for degree of protection IP 65. The door locking device reliably prevents accidental opening of the cubicle door in the ON position of the MSP.. The OFF position can be locked with up to 3 padlocks. Auxiliary releases for lateral mounting and 2-pole auxiliary switches can be used. The door-coupling rotary operating mechanism thus conforms with isolator characteristics to IEC 60 947-2.