TEMPERATURE MONITORED CABLE SYSTEM WITH TELEMETRY READOUT

• US 3,633,191 A
• Filed: 07/07/1969
• Issued: 01/04/1972
• Est. Priority Date: 09/20/1966
• Status: Expired due to Term

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: John Sherman Engelhardt, Lawrence Charles Ebel
• Inventors: Engelhardt, John Sherman, Ebel, Lawrence Charles
• Primary Examiner(s): Caldwell, John W.
• Assistant Examiner(s): Mooney, Robert J.
• Application Number:
  US04/839,571
• Time in Patent Office: 911 Days
• Field of Search: 340/207,208,227,228,233,27P,227C 332/43B,47 73/342,362,362R,362AR
• US Class Current: 340/870.11
• CPC Class Codes: G01K 1/024 for remote indication
• CPC Class Codes: G01K 3/02 giving means values; giving integrated values
• CPC Class Codes: H02H 7/226 for wires or cables, e.g. heating wires

Abstract

In order to accurately and instantaneously measure the average temperature of a length of current carrying conductor such as a high-tension cable, a pilot wire having a conductivity which varies according to its temperature is provided a thermal communication with the conductor along its entire length, so that the conductor and pilot wire are at essentially the same temperatures but are electrically insulated from one another along their common lateral extent. A circuit is provided for measuring the conductivity and thereby the temperature of the pilot wire, and a radio telemetry transmitter transmits this information to a receiver on the ground, from which it may be retransmitted to any desired remote location. The provision of multiple pilot wires in one embodiment of the invention permits measurements of more than one segment of the conductor to be made and transmitted.

Claims

1. Apparatus for measuring the average temperature of the length of current carrying conductor, comprising:

conductive means, the conductivity of which varies according to its temperature, electrically insulated from the currentcarrying conductor along their common lateral extent and in thermal communication therewith along substantially its entire length, so that the conductor and the conductive means are at essentially the same temperature;

means for measuring the conductance of the conductive means;

a radio transmitter connected to the measuring means for transmitting signals representative of said conductance to a receiver; and

a source of DC current supplying current to the measuring means, said measuring means including a Wheatstone bridge circuit, one arm of which includes said length of current-carrying conductor connected in series with the conductive means, said DC current source being connected diagonally across the Wheatstone bridge circuit for supplying current thereto.

2. Apparatus as defined in claim 1 wherein said source of DC current includes means for deriving AC power from the current carrying conductor and for rectifying said AC power to produce said DC current, said AC power deriving means being a transformer, the primary winding of which is said current-carrying conductor.

3. Apparatus for measuring the average temperature of a length of current-carrying conductor terminating at one end in a pothead, said apparatus comprising:

conductive means, the conductivity of which varies according to its temperature, electrically insulated from the current-carrying conductor along their common lateral extent and in thermal communication with said conductor along substantially its entire length, so that the conductor and the conductive means are at essentially the same temperatures;

a housing mounted on such pothead for excluding external electric and magnetic fields, said housing being formed of an electrically conductive material and provided with rounded edges for corona shielding;

means mounted in said housing for measuring the conductance of said conductive means; and

a radio transmitter mounted in said housing and connected to said measuring means for transmitting signals representative of said conductance to a receiver.

4. Apparatus as defined in claim 3 wherein said radio tranSmitter includes a flush antenna mounted integrally with said housing for radiating said signals.

5. Apparatus as defined in claim 3 wherein said housing is formed integrally with such pothead.

6. Apparatus as defined in claim 3 including a corona ring mounted on such pothead, said housing being mounted on said corona ring.

7. In apparatus for electrically measuring and transmitting the value of a parameter characterizing a current-carrying cable, which cable terminates at one end in a pothead, the improvement comprising a housing integral with such pothead for excluding external electric fields, said housing being formed of an electrically conductive material and having rounded edges for corona shielding;

a flush antenna mounted integrally on said housing; and

means within said housing for measuring the value of such parameter and including a radio transmitter connected to said antenna for transmitting signals representative of said value.

8. Apparatus as defined in claim 7 wherein said radio transmitter includes a biphase modulator.