EP0034031A1
Expired / Lapsed
EP
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Electricity meters
Assignee: Gemalto Terminals Ltd
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Filing: 1981-02-02
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Granted: —
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Expires: 2001-02-02
Abstract
Abstract An electricity meter for metering the amount of electrical energy supplied by a power supplier to a power consumer is provided with means for detecting the presence of an external shunt (50) which has been connected to by-pass its internal current sensing means (22). The detecting means, which in one embodiment comprises a differential current sensor (32, 34) for sensing the difference between the respective currents flowing to and from the consumer via the meter, is arranged to operate a circuit breaker (44) and/or to compensate the energy measurement of the meter, and/or to provide a warning to the supplier. The differential current sensor also senses when current is being taken between the live wire and earth on the consumer's side of the meter.
Inventors
- 👤 Howard Anthony Dorey
- 👤 Anthony John Ley
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-25 23:53
CPC Classifications
G; G01; G01R; G01R22/00; G01R22/06; G01R22/061; G01R22/066; G01R21/00; G08; G08B; G08B29/00; G08B29/02; G08B29/06; G08B29/08
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
123 words
An electricity meter for measuring the amount of electrical energy supplied by an electrical power supplier to an electrical power consumer via an electrical power distribution circuit consisting of at least two wires, the meter comprising: current sensing means for sensing the current flowing in at least one of the wires; and means responsive to the current sensed by the current sensing means for deriving the energy measurement; the meter being characterised by fraud detection means for detecting attempts to fraudulently bypass the meter, said fraud detection means being operative to produce a signal indicative of such an attempt when the resistive component of the difference between the respective currents flowing to and from the consumer via the meter exceeds a predetermined value.
Claim 2
Dependent Claim
123 words
An electricity meter for measuring the amount of electrical energy supplied by an electrical power supplier to an electrical power consumer via an electrical power distribution circuit consisting of at least two wires, the meter comprising: current sensing means for sensing the current flowing in at least one of the wires; and means responsive to the current sensed by the current sensing means for deriving the energy measurement; the meter being characterised by fraud detection means for detecting attempts to fraudulently bypass the meter, said fraud detection means being operative to produce a signal indicative of such an attempt when the resistive component of the difference between the respective currents flowing to and from the consumer via the meter exceeds a predetermined value.
Claim 3
Dependent Claim
31 words
An electricity meter as claimed in claim 1, characterised in that said fraud detection means includes means arranged to produce a signal representative of the instantaneous value of said current difference.
Claim 4
Dependent Claim
51 words
An electricity meter as claimed in claim 2, characterised in that said fraud detection means further includes an electronic multiplier arranged to multiJly the current difference representative signal by a signal representative of the instantaneous value of the voltage between the wires to produce a signal representative of the product thereof.
Claim 5
Dependent Claim
61 words
An electricity meter as claimed in claim 3, characterised in that said fraud detection means further includes integrating means arranged to receive and integrate said product representative signal for a predetermined time and to produce said signal indicative of an attempt to bypass the meter when the integral of the product representative signal exceeds a predetermined value within the predetermined time.
Claim 6
Dependent Claim
51 words
An electricity meter as claimed in any one of claims 2 to 4, characterised in that the means for producing the current difference representative signal comprises a toroidal core through which each of said wires is arranged to pass, and a coil wound upon at least a portion of said core.
Claim 7
Dependent Claim
45 words
An electricity meter as claimed in any one of claims 1 to 5, for use in a distribution circuit having a live wire and a neutral wire, characterised in that the current sensing means is arranged to sense the current flowing in the neutral wire.
Claim 8
Dependent Claim
163 words
An electricity meter for measuring the amount of electrical energy supplied by an electrical power supplier to an electrical power consumer via an electrical power distribution circuit consisting of at least two wires, the meter comprising: current sensing means for sensing the current flowing in at least one of the wires; and means responsive to the current sensed by the current sensing means for deriving the energy measurement; the meter being characterised by fraud detection means for detecting attempts to fraudulently bypass the meter, said fraud detection means comprising means for applying to the current sensing means a reference signal whose frequency is different from that of the AC power signal and which produces in the current sensing means, in response to such an attempt, a signal which is distinguishable from the signal produced in the current sensing means by the current from the power supplier, and means arranged to produce a signal indicative of the attempt in response to said distinguishable signal.
Claim 9
Dependent Claim
163 words
An electricity meter for measuring the amount of electrical energy supplied by an electrical power supplier to an electrical power consumer via an electrical power distribution circuit consisting of at least two wires, the meter comprising: current sensing means for sensing the current flowing in at least one of the wires; and means responsive to the current sensed by the current sensing means for deriving the energy measurement; the meter being characterised by fraud detection means for detecting attempts to fraudulently bypass the meter, said fraud detection means comprising means for applying to the current sensing means a reference signal whose frequency is different from that of the AC power signal and which produces in the current sensing means, in response to such an attempt, a signal which is distinguishable from the signal produced in the current sensing means by the current from the power supplier, and means arranged to produce a signal indicative of the attempt in response to said distinguishable signal.
Claim 10
Dependent Claim
34 words
An electricity meter as claimed in claim 7, characterised in that the reference signal is an A.C. signal whose frequency is higher than, but not harmonically related to, that of the A.C. power signal.
Claim 11
Dependent Claim
19 words
An electricity meter as claimed in claim 7, characterised in that the reference signal is a pseudo-random binary signal.
Claim 12
Dependent Claim
77 words
An electricity meter as claimed in any preceding claim, characterised by means responsive to said signal indicative of an attempt to bypass the meter to effect at least one of the following operations: a) to discontinue the supply of electricity to the consumer; b) to transmit the signal to the supplier; c) to operate a signal device associated with the meter; and d) to at least partly compensate the energy measurement for the effect of the attempt.
Claim 13
Dependent Claim
155 words
An electricity meter for measuring the amount of electrical energy supplied by an electrical power supplier to an electrical power consumer via an electrical power distribution circuit consisting of at least two wires, the meter comprising: current sensing means for sensing the current flowing in at least one of the wires; and means responsive to the current sensed by the current sensing neans for deriving the energy measurement; the meter being further characterised by fraud detection means comprising a transformer having a primary winding connected to receive, in operation, the voltage between two of the wires of the distribution circuit and a secondary winding connected in series with the current sensing means such that, in the presence of an external shunt connected to bypass the current sensing means, a current sufficient to at least partly compensate the energy measurement for the presence of the external shunt is caused to flow in the current sensing means.
Claim 14
Dependent Claim
155 words
An electricity meter for measuring the amount of electrical energy supplied by an electrical power supplier to an electrical power consumer via an electrical power distribution circuit consisting of at least two wires, the meter comprising: current sensing means for sensing the current flowing in at least one of the wires; and means responsive to the current sensed by the current sensing neans for deriving the energy measurement; the meter being further characterised by fraud detection means comprising a transformer having a primary winding connected to receive, in operation, the voltage between two of the wires of the distribution circuit and a secondary winding connected in series with the current sensing means such that, in the presence of an external shunt connected to bypass the current sensing means, a current sufficient to at least partly compensate the energy measurement for the presence of the external shunt is caused to flow in the current sensing means.
Claim 15
Dependent Claim
14 words
An electricity meter as claimed in claim 11, wherein the transformer is an auto-transformer.
Claim 16
Dependent Claim
64 words
An electricity meter as claimed in any preceding claim, for use in a distribution circuit having at least one live wire, the meter having a switch series connected in said live wire and further comprising means for detecting the presence of the supply voltage down-circuit of the switch after the switch has opened and for producing a warning signal in response to such detection.
Claim 17
Dependent Claim
55 words
An electricity meter as claimed in claim 13, further characterised by means responsive to said warning signal to effect at least one of the following operations: a) to transmit the warning signal to the supplier; b) to operate a warning device associated With the meter; and c) to increase the energy measurement of the meter.
References Cited (Backward Citations)
DE491420C
Cited
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