Transmission line sensor apparatus operable with near zero current line conditions

• US 4,886,980 A
• Filed: 08/22/1988
• Issued: 12/12/1989
• Est. Priority Date: 11/05/1985
• Status: Expired due to Term

• Current Assignee: Undersground Systems, Inc.
• Original Assignee: Niagara Mohawk Power Corporation (National Grid PLC)
• Inventors: Fernandes, Roosevelt A., Sieron, Richard L.
• Primary Examiner(s): Shoop, Jr., William M.
• Assistant Examiner(s): IP, SHIK LUEN PAUL
• Application Number:
  US07/234,688
• Time in Patent Office: 477 Days
• Field of Search: 307/64, 307/66, 307/48, 307/52, 307/128, 307/129, 307/130, 307/131, 307/87, 324/51, 324/78 R, 324/126, 324/127, 340/870.11, 340/870.16, 340/870.17, 340/870.28, 340/870.37, 340/870.38, 340/870.39, 361/44, 361/45, 361/57, 361/56, 361/63, 361/64, 361/65, 361/72, 361/79, 361/78, 361/86, 361/87, 361/88, 361/90, 361/91, 361/92, 361/93, 310/308, 310/309, 310/310, 364/492, 364/493
• US Class Current: 307/64
• CPC Class Codes: G01R 15/142 Arrangements for simultaneous measurements of several parameters employing techniques covered by groups G01R15/14 - G01R15/26

Abstract

A self contained sensor module mounted on a power transmission line. The module is capable of measuring various parameters such as line current, voltage, conductor temperature, and ambient temperature. The parameter values are processed by sensor electronics which digitize and transmit the values to a ground receiver. The sensor module normally derives its power through electromagnetic induction resulting from current flowing through the transmission line. The module contains a power back-up system, including a battery, which allows sensor operation with minimum current and zero current in the transmission line. The battery is float charged while the sensor is mounted on the transmission line using excess energy derived through electromagnetic induction. When line current drops to a predetermined minimum value, float charging is disabled and the battery supplies power to the sensor module. When battery power is depleted to a predetermined level, data processing and transmission are disabled until the battery can be recharged.

Claims

1. A system for monitoring a plurality of parameters associated with each of a plurality of energized electrical power conductors, on power system circuits operable over a load range between predetermined minimum and maximum conductor currents in either direction, said system comprising:

(a) a plurality of sensor modules for measuring the parameters of said conductors while said conductors are energized, one of said modules being mounted upon each of said energized conductors;

(b) means carried by each of said modules for measurement of conductor voltage;

(c) means carried by each of said modules for measurement of the current through said conductor over said entire load range;

(d) means carried by each of said modules for processing and storing said sensed values of conductor voltage and conductor current;

(e) means carried by each of said modules for transmitting signals comprising a sequence of data commensurate with said measured values;

(f) power supply means for providing power to each of said processing means and each of said transmitting means from said conductor current when the latter is above a predetermined value;

(g) a rechargeable energy storage device in each of said modules for providing power to its respective processing and transmitting means when said conductor current is below said predetermined value;

(h) charging means coupled to said power supply means and said storage device for float charging said storage device from said power supply means; and

(i) means remote from said modules for receiving said signals from said transmitting means of each of said plurality of sensor modules, decoding said signals and calculating voltage and current of each of said conductors.

2. The system according to claim 1 wherein said rechargeable energy storage device in each module is a battery.

3. The system according to claim 2 and further including means carried by each of said modules for charging said battery by energy derived from said energized conductors.

4. The system according to claim 1 and further including means carried by each of said sensor modules for establishing the phase relationship between said sensed values of conductor voltage and conductor current, and wherein said signals include data commensurate with said phase relationship.

5. The system according to claim 1 and further including means carried by each of said sensor modules for measuring the frequency of said conductor voltage and conductor current, and wherein said signals include data commensurate with the frequency of said conductor voltage and current.

6. The system according to claim 1 and further including means carried by each of said modules for calculating, from said sensed values of conductor voltage and current, and storing power and energy related quantities including megawatts, megawatthours and power factor, and said signals include data commensurate with said quantities.

7. The system according to claim 1 wherein said remote means includes means for calculating, from said values of conductor voltage and current, power and energy related quantities including megawatts, megawatthours and power factor.