Threshold circuit for detecting and indicating an overvoltage

Abstract

Abstract A THRESHOLD CIRCUIT FOR DETECTING AND INDICATING AN OVERVOLTAGE. AN EXAMPLE BEING TO SENSE THE VOLTAGE AT AN ANTENNA BEING FED FROM A TRANSMITTER THROUGH AN ANTENNA COUPLER. A SWITCHING CONTACT AND AN OPERATING COIL THEREFORE ARE CONNECTED IN SERIES CIRCUIT COMBINATION WITH A FIST CAPACITOR CONNECTED ACROSS THE OPERATING COIL. AFTER THE FIRST CAPACITOR CHARGES TO APPROXIMATELY THE PEAK OF THE VOLTAGE BEING MONITORED, CURRENT THROUGH THE OPERATING COIL WILL BE SUFFICIENT TO ACTUATE THE SWITCHING CONTACT SHOULD THE SENSED VOLTAGE EXCEED THE PREDETERMINED THRESHOLD VALUE. AFTER ACTUATION OF THE SWITCHING CONTACT, THE OERATING COIL AND FIRST CAPACITOR ARE DISCONNECTED FROM THE VOLTAGE TO BE SENSED WHEREUPON THE FIRST CAPACITOR DISCHARGES THROUGH THE OPERATING COIL TO MAINTAIN THE SWITCHING CONTACT IN ITS ACTUATED POSITION UNTIL THE DISCHARGE CURRENT IS LESS THAN THE HOLD-IN CURRENT REQUIREMENT OF THE OPERATING COIL. THE SWITCHING CONTACT WILL THEN RETURN TO ITS NORMAL POSITION AND AS LONG AS THE VOLTAGE TO BE SENSED REMAINS ABOVE THE THRESHOLD LEVEL, THE OPERATING COIL WILL BE ALTERNATELY ENERGIZED AND DEENERGIZED THROUGH THE ACTION OF THE SWITCHING CONTACT. A SECOND CAPACITOR MAY BE ADVANTAGENOUSLY CONNECTED ACROSS THE SWITCHING CONTACT TO MOMENTARILY DRAW CURRENT THROUGH THE OPERATING COIL FROM THE OVERVOLTAGE SOURCE TO ALLOW THE SWITCHING CONTACT TO COMPLETE ITS SWITCHING CYCLE WITHOUT CHATTERING.

Inventors

• 👤 Harvey M Masters

Bibliographic Details