| 摘要 |
PURPOSE:To prevent malfunction and to make safe the replacement work of an exchanger, by turning off a switch during the replacement work of the exchanger, through the provisin of the switch which cuts off a battery feed current between a ringer relay circuit of a subscriber circuit and a test relay circuit. CONSTITUTION:An old type exchanger in a station office 11 is replaced into a time sharing exchanger 9'. In subscriber circuits 6'-1-6'-n of a subscriber line device 7' of the exchanger 9', switches 12-1 and 12-n connected between test relay circuits 3-1-3-n and ringer relay circuits 2-1-2-n are provided. When the exchanger 10 and the exchanger 9' are connected to telephone terminal sets 4-1-4-n with telephone lines 5-1-5-n, switches 12-1-12-n are turned off to disconnect battery feed circuits 1-1-1-n of the circuits 6'-1-6'-n from the exchanger 10 to execute stable exchange operation test. |
