Method and system for sensing removal of a utility meter from its socket

• US 5,422,565 A
• Filed: 12/07/1993
• Issued: 06/06/1995
• Est. Priority Date: 08/06/1991
• Status: Expired due to Term

• Current Assignee: Itron, Inc.
• Original Assignee: Schlumberger Industries Incorporated (Schlumberger NV)
• Inventors: Swanson, Scott C.
• Primary Examiner(s): NGUYEN, VINH P
• Application Number:
  US08/163,215
• Time in Patent Office: 546 Days
• Field of Search: 324/110, 324/156, 324/157, 340/568, 340/637, 340/571, 340/572, 340/565, 340/568, 361/372, 364/481, 364/483, 364/550, 364/551.01
• US Class Current: 324/110
• CPC Class Codes: G01R 22/066 Arrangements for avoiding or indicating fraudulent use
• CPC Class Codes: G08B 13/1409 for removal detection of electrical appliances by detecting their physical disconnection from an electrical system, e.g. using a switch incorporated in the plug connector

Abstract

A method and system is disclosed for indication and prevention of tampering with an electricity meter having control circuitry for automatic remote reading. The control circuitry, provided externally of the meter in a base or base extension, to which the meter is connected, is also used for tamper detection. Embodiments of the invention include use of optical sensing, voltage detection and proximity detection. Ambient light sensing may be performed to detect separation of the meter from the external receptacle. Reflected light to a reflective surface of the meter is sensed to determine if the meter is properly engaged. Presence of a meter connection plug element may be sensed either optically or by position responsive switch. Voltage of the utility supply and meter user output may be monitored to determine tampering.

Claims

1. A device for detecting tampering of a connection between an electricity meter and an external power supply system, said device comprising:

means for detecting voltage of power supplied to said meter from said external power supply system;

means for detecting voltage of power output from said meter to a load circuit; and

means including a microprocessor for detecting a meter tampering condition in response to the detected power supply voltage and the detected load circuit voltage.

2. A device as recited in claim 1, wherein said means for detecting voltage of power supplied to said meter comprises a transformer having a primary winding disposed across lines from said external power supply system to said meter and having a secondary winding configured to communicate with said microprocessor.

3. A device as recited in claim 1, wherein said means for detecting voltage of power output from said meter comprises a phototransistor in communication with said microprocessor and a light emitting diode situated across lines from said meter to said load circuit and positioned to radiate light to said phototransistor.

4. A method for ascertaining tampering of a connection between an electricity meter and an external power supply system, comprising the steps of:

detecting voltage of power supplied to said meter from said power supply system;

detecting voltage of power output from said meter to a load circuit; and

indicating a meter tampering condition when said voltage of power supplied to said meter from the power supply system is relatively high and said voltage of power output to said load circuit is relatively low.

5. A method as recited in claim 4, further comprising the step of detecting said voltage of power supplied to said meter using a transformer having a winding connected across lines for supplying power to said meter.

6. A method as recited in claim 4, further comprising the step of receiving light from a light emitting diode situated across lines from said meter to said load circuit in order to detect said voltage of power output from said meter.