Patent ID: 6292105
Filing Date: 2001-09-18
Classification: G08B

Abstract:
A temperature sensor for detecting the early outgassing of overheated electrical installation comprising:an ionization chamber containing a radioisotope for providing ionization inside the chamber;a direct current (DC) power supply for appying a voltage potential across the ionization chamber thereby inducing ions to flow within the ionization chamber;the ionization chamber further comprising:an outer cap electrode connected to the plus voltage of the DC power supply;a source electrode connected to ground;a collector electrode for dividing the ionization chamber into two sections, an upper section between the collector electrode and the outer cap electrode and a lower section between the collector electrode and the source electrode whereby the collector electrode is charged to a potential by the ionization currents flowing within the ionization chamber, the ionization currents coming into balance between the two sections;a high input impedance operational amplifier for buffering the potential at the collector electrode;a comparator, the output of the comparator changing state based on a reference voltage;a voltage divider for supplying the reference voltage to the comparator;wherein particles from the early outgassing of overheated electrical insulation enter the ionization chamber causing an imbalance in the ionization current flow in the upper and lower sections of the ionization chamber thereby causing the potential at the collector electrode to fall below the reference voltage for the comparator and triggering an alarm.