| 摘要 |
PROTECTION DEVICES AND ARRANGEMENTS FOR TELEPHONE LINES A two-wire telephone subscriber line protection arrangement consists of two protection devices each comprising a pair of complementary thyristors connected in reverse parallel with one another between a respective wire and a reference point, with their gates connected together and directly to a control terminal which has a connection to the wire via a resistance which determines an overcurrent threshold level for the device. The reference point is ground for the ring wire protection device, and is desirably the ring wire for the tip wire protection device, whereby a directional sensitivity of the protection devices is taken advantage of and the overcurrent threshold level can be reduced. Zener diodes connected between complementary thyristors provide for convenient overvoltage protection. |
