Modular distributor for controlling group of electric drives

A series of modular distributors, RASK, was developed for controlling a group of electric drives in coal mines or other mines, where a large number of contractors must be protectively enclosed. Unlike conventional distributors with three electromagnets for circuit closing, circuit opening, and zero-sequence protection respectively, a RASK distributor has only one main electromagnet for circuit closing. The other two functions are performed by small auxiliary electromagnets, their number being equal to the number of controlled drives and additional contactors being provided for their operation as intermediate relays. Such a distributor not only switches drives on or off, selectively and independently rather than sequentially, but also commutates the arc-quenching circuits. All circuits can be controlled by current signals transmitted over two or three wires, either all or only some controlled circuits to be closed or opened, and all circuits can be opened simultaneously for zero-sequence protection. The advantages of fewer components are appreciable reduction of metal content.