METHOD OF AND APPARATUS FOR MONITORING FOR INCIPIENT ELECTRODE FAILURE IN THE JOULE EFFECT HEATING OF HEAT SOFTENABLE MATERIAL

摘要

1527082 Measuring resistance OWENSCORNING FIBERGLAS CORP 14 Oct 1975 [15 Oct 1974] 42042/75 Heading G1U In a process for heating glass by the Joule effect, incipient electrode failure is detected by monitoring voltage across and current flowing two pairs of electrodes, an indication of resistance derived therefrom being provided. Heating of the molten glass 18 is achieved by pulses derived from controlled switching 28 of paralleled thyristors 26, 27 in the supply paths between supply transformers 29 and electrode pairs with single 12-15 or multi-elements 16. Current and voltage to each electrode pair is sequentially monitored under computer 51 control via de-coder 68, relays R1-R6 and their contacts. Conventional R.M.S. converters 48, 61 apply the true R.M.S. voltage and current values to the computer 51 which computes the resistance, compares it to a predetermined value, which may be periodically updated to account for normal acceptable ageing, and operates a display. The display incorporates an electrode identification and alarm indication, operated when the resistance of the electrode pair exceeds the predetermined value, indicating incipient failure.