In this exchanger every subscriber circuit has only one relay, and from the contacts, double line matrix is composed; each cord circuit uses only three relays.Through the vertical bar displacement spring contacts, the circuit of busy tone is connected, it has a keyboard which transmitts 1,2,4,5,codes of d.c. signals for various calling or switching. Its control circuit has a "four combined into one" circut which consists of storage, decoding, double line measuring coordinate and driving. It adopts series connection voltage-stabilized source which is of less consumption of electricity with a capacity of 30-60-90 subscriber.