HIGH VOLTAGE DETECTING SYSTEM FOR SUBSCRIBER LINE

PURPOSE:To discriminate an abnormal high voltage, by reconnecting a subscriber without normal dial to a high voltage detector, before it is connected to a sound source transmission trunk. CONSTITUTION:When an abnormal high voltage HV of commercial power supply is applied to a subscriber line L, a relay LR of a subscriber circuit LC is operated, and connection is made to an outgoing register trunk ORT via a path 1 in a network NW, as if a subscriber SUB had made a call, but the reception of normal reception is not made. A central controller reconnects the subscriber circuit LC from the outgoing register trunk ORT to the high voltage detector HDT. In the HDT, a relay CH is operated with the HV and a contact (ch) is closed. The central controller detects the closing of a contact (cr) via a scanner SCN to discriminate that the abnormal high voltage HV is applied to the subscriber line L, allowing to disconnect the subscriber line L from an electronic exchanger.