Open thermocouple tester system
AssigneeElectronic Associates, Inc.
InventorAlbert M. Paulson
Life of this patent
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Abstract
A system for testing open thermocouples in a data acquisition system in which each of a plurality of thermocouples is sequentially read. Each thermocouple has an associated filter capacitor and resistance network and each has a different common-mode voltage with respect to a reference potential. Charging means is effective to charge each filter capacitor in sequence after a reading has been taken. For a normal thermocouple, the filter capacitor discharges through the associated resistance and thermocouple prior to the next sequential reading of that thermocouple. For an open thermocouple the filter capacitor remains charged indicating that the thermocouple is open at the time of the next sequential reading of that thermocouple.
Claims6
In a data acquisition system for sequentially reading by way of monitor means a plurality of thermocouples each having a permanently coupled filter capacitor and resistance network, an open thermocouple tester system comprising
- floating charge means for sequentially charging each of said filter capacitors,
- switching means for sequentially coupling each of said filter capacitors to said floating charge means and monitor means,
- a source of supply for charging said floating charge means,
- first isolating means for isolating said floating charge means from said switching means and monitor means during a first duration during which said monitor means sequentially reads each of said filter capacitors, whereby (1) for a normal thermocouple said filter capacitor discharges through said thermocouple and (2) for an open thermocouple said filter capacitor remains charged, and,
- second isolating means for isolating said source of supply from said floating charge means for a second duration during which said floating charge means sequentially charges each of said filter capacitors.
Dependencies are inferred from the claim text.