US 4,571,689 AGranted

Multiple thermocouple testing device

AssigneeThe United States of America as represented by the Secretary of the Air Force

InventorsJames R. Hildebrand, Kurt J. Sobanski

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Abstract

An automated multiple thermocouple testing device determines short and open circuits in a thermocouple system. The thermocouple system has a plurality of temperature probes, each probe has a first thermocouple and a second thermocouple. The device applies a direct current voltage to the first thermocouple to cause heating in the second thermocouple and then reads the temperature response of the second thermocouple. The first thermocouples have a common lead and the second thermocouples are connected in two parallel groups. The temperature output of the second thermocouple is digitized and read by a computer. These readings are compared to criteria which determines if there is an open circuit. Before the open circuit test is applied, the device also determines which thermocouple probe has a possible short circuit. This device can automatically test for short and open circuits in a thermocouple system within a few minutes without the necessity of removing the probes from their installed position. This device was adapted to preform the above testing on a F100 fan turbine inlet temperature (FTIT) system.

Claims10

Dependent claims

A multiple thermocouple testing device for determining electrical short and open circuits in a thermocouple system, said thermocouple system having a plurality of probes, each of said probes having a first thermocouple and a second thermocouple, said second thermocouples of said probes are connected in a plurality of parallel groups, said multiple thermocouple testing device comprising

a computer programmed to:
read test values, compare test values to defined constants, direct current to a selected first thermocouple, output results of the comparison, check test values for noise, and control functioning of said multiple thermocouple testing device, said computer starting upon a given command, and returning to start upon being reset;
means for providing direct current voltages to said computer;
means for selectively applying a direct current voltage to said selected first thermocouple of said thermocouple system, said direct current voltage being input to said means for selectively applying by said means for providing direct current voltages;
means for interfacing, said means for interfacing receiving a plurality of direct current voltages from said means for providing direct current voltages for powering said means for interfacing, said means for interfacing connected to said computer for inputting data thereto and receiving data therefrom, said means for interfacing outputting control signals to said means for selectively applying a direct current voltage to said thermocouple system, and said means for interfacing connected to receive analog signals from said thermocouple system and digitizing said signals;
and
means for displaying said output results, said means for displaying connected to said means for interfacing.

4 more elements

Dependencies are inferred from the claim text.