device for the protection of electrical equipment - electronic telephone exchanges against the electrical disturbance interesting the telecommunication lines connected to the same power.

摘要

The device, interposed between the terminals AR, BR of a network connection and the terminals AC, BC of an exchange connection, comprises two resistors R, through each of which the current from the corresponding network terminal passes, and across whose terminals there is established a potential difference which is used, if the said current exceeds a predetermined value, as the signal for activating a corresponding electronic unit 20. The activation of a unit causes the connection of the corresponding network terminal to an earth terminal 3; the unit is also activated if the voltage present across its terminals exceeds a predetermined value. The units 20 are integrated with a three-pole arrester 40, branched between the network terminals, whose operation is co-ordinated with the activation of the units by means of two non-linear PCT resistors 30, each of which is interposed between the arrester and the corresponding unit 20 and has the current from the corresponding network terminal passing through it. IMAGE