PROTECTIVE DEVICE OF THREE-WIRE COMMUNICATION LINES (MODIFICATIONS) Russian patent published in 2002 - IPC

FIELD: communication engineering, applicable for protection of telephone exchange centers against overvoltages arising at getting of the 220-V mains voltage in the telephone lines, lighting discharges and interferences caused by them, or interferences caused by failures of the power transmission lines. SUBSTANCE: the device has two temperature- sensitive resistors with a positive temperature coefficient, which are connected between the respective input and output contacts of the device, and two arresters cut in between the input electrode of the respective temperature-sensitive resistor and the device contact connected to the earthed line of the three-wire communication lines. An additional device has two varistors connected in parallel with the arresters between the output electrode of the respective temperature-sensitive resistor and the device contact connected to the earthed line of the three-wire communication lines. The varistors may be made in the form of a plate or plates of high nonlinear material with electrodes located on both sides or on the ends of the plate with temperature-sensitive resistors located over the electrodes of the varistors. EFFECT: enhanced speed of response and service life. 2 cl, 3 dwg