Cold junction thermocouple compensator

• US 4,133,700 A
• Filed: 12/21/1977
• Issued: 01/09/1979
• Est. Priority Date: 03/13/1975
• Status: Expired due to Term

• Current Assignee: Omega Engineering Incorporated (Spectris PLC)
• Original Assignee: Omega Engineering Incorporated (Spectris PLC)
• Inventors: McKinley, William E., Hollander, Betty R.
• Primary Examiner(s): Sebastian, Leland A.
• Application Number:
  US05/862,879
• Time in Patent Office: 384 Days
• Field of Search: 136/222, 136/242, 324/105, 73/341, 73/361, 340/227 D, 340/228 R
• US Class Current: 374/181
• CPC Class Codes: G01K 7/12 Arrangements with respect to the cold junction, e.g. preventing influence of temperature of surrounding air
• CPC Class Codes: H10N 10/00 Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects integrated devices or assemblies of multiple devices H10N19/00
• CPC Class Codes: H10N 10/13 characterised by the heat-exchanging means at the junction

Abstract

0°COLD JUNCTION COMPENSATOR PROVIDES THE ELECTRICAL EQUIVALENT OF AN ICE-BATH REFERENCE THERMOCOUPLE, AT A SELECTED TEMPERATURE, FOR EXAMPLE O° C. Input connectors, for engagement with conventional thermocouple units, form thermocouple junctions with conductors connected to a battery-operated Wheatstone bridge circuit adapted to supply an equal and opposite voltage output compensating for variations in the thermocouple junction output at different ambient temperatures. The compensator may be included in a module having input sockets or input plugs to coact with plugs or sockets of conventional thermocouple units. The compensator and battery may be encapsulated, or an accessible switch may be included in the battery circuit.

Claims

1. A cold junction compensator module comprising:

(i) an elongated housing having a first end and a second end and including a body portion;

(ii) a cold junction compensator circuit mounted on said body portion and including;

(a) a first input connector for connection to a first element of a sensing thermocouple, said first element being made of one material of a thermocouple junction, said first input connector being mounted at said first end of said body portion,

(b) a second input connector for connection to a second element of said sensing thermocouple, said second connector being made of said one material of said thermocouple junction, said second input connector being mounted at said first end of said body portion,

(c) a first copper conductor forming a thermocouple junction with said first connector,

(d) a second copper conductor forming a thermocouple with said second connector,

(e) first and second output terminals, mounted at said second end of said body portion,

(f) an electrical connection between said first conductor and said first output terminal,

(g) a Wheatstone bridge circuit including a supply battery, an arm of said bridge being constituted by matched Thermistors disposed in mutually balancing positions, said bridge circuit being arranged such that, over a range of temperature, it generates a voltage which at any temperature is equal and opposite to the voltage differential generated by said thermocouple junctions at that temperature, said bridge circuit being connected between said second conductor and said second output terminal,

(iii) a major cover extending from said first end of said body portion over a major part of the length of said body portion, said body portion and said major cover being apertured at said first end such that with said major cover secured on said body portion said input terminals are accessible from the exterior of the module,

(iv) a minor cover extending from said second end over a minor part of the length of said body portion, said minor cover covering said output terminals and preventing access thereto from the exterior of the module.