EP0240102A2
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EP
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Power meter having self-test function
Assignee: ROBINTON PRODUCTS Inc
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Filing: 1987-01-20
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Granted: —
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Expires: 2007-01-20
Abstract
Abstract An electronic metering system having self-test capabilities. First and second analog signals are produced which are indicative of the voltage and current, respectively, carried on a line. The first analog signal is modulated to provide a digital signal changeable between two levels at predetermined clock times. The ratio of duration of the signal at one level to that of the second level is proportional to the line voltage. The modulated signal and second analog signal are multiplied together to produce a product signal which represents power carried on the line in either direction. The product signal is converted to a train of pulses, with each pulse representing a predetermined amount of power. Self-test capability is provided wherein a test signal is momentarily substituted for the first analog signal, with the test signal corresponding to a line voltage of zero magnitude. A comparator is provided for confirming that the converted product signal corresponds to zero power carried on the line in either direction when the test signal is applied. If the converted signal differs from zero power more than a predetermined amount, an error signal is produced indicating a meter system malfunction.
Inventors
- 👤 Lev M. Dawson
- 👤 Michael A. Robinton
- 👤 Alan H. Starkie
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 12:41
CPC Classifications
G; G01; G01R; G01R21/00; G01R21/133; G01R35/00; G01R35/04
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
218 words
An electrical power meter having intemal self-test capabilities, said meter comprising: monitoring means for producing a first analog signal indicative of one of voltage and current carried on a line and for producing a second analog signal indicative of the other of said voltage and current; first modulator means for producing a first modulated signal changeable between two levels and indicative of the magnitude of said first analog signal; first multiplying means for producing a first product signal, from said first modulated signal and said signal analog signal, which is indicative of power carried on the line; first converter means for producing a first converted signal from said first product signal in the form of a train of pulses, with each of said pulses representing a predetermined amount of power carried on the line; first test means for momentarily applying a predetermined first test signal to an input of said first modulator means in lieu of said first analog signal; first memory means for storing a first converted signal value which corresponds to said first test signal; and first comparator means for producing a first error signal when said first converted signal differs from said stored first converted signal value more than a predetermined amount when said first test signal is applied to said first modulator means input.
Claim 2
Dependent Claim
218 words
An electrical power meter having intemal self-test capabilities, said meter comprising: monitoring means for producing a first analog signal indicative of one of voltage and current carried on a line and for producing a second analog signal indicative of the other of said voltage and current; first modulator means for producing a first modulated signal changeable between two levels and indicative of the magnitude of said first analog signal; first multiplying means for producing a first product signal, from said first modulated signal and said signal analog signal, which is indicative of power carried on the line; first converter means for producing a first converted signal from said first product signal in the form of a train of pulses, with each of said pulses representing a predetermined amount of power carried on the line; first test means for momentarily applying a predetermined first test signal to an input of said first modulator means in lieu of said first analog signal; first memory means for storing a first converted signal value which corresponds to said first test signal; and first comparator means for producing a first error signal when said first converted signal differs from said stored first converted signal value more than a predetermined amount when said first test signal is applied to said first modulator means input.
Claim 3
Dependent Claim
37 words
The power meter of Claim 1 wherein said first test signal corresponds to said first analog signal of zero amplitude and said stored first converted signal value corresponds to power carried on the line of zero amplitude.
Claim 4
Dependent Claim
66 words
The power meter of Claim 1 further including second memory means for storing a first modulated signal value which corresponds to said first test signal and second comparator means for producing a second error signal when said first modulated signal differs from said stored first modulated signal value by more than a predetermined amount when said first test signal is applied to said first modulator means.
Claim 5
Dependent Claim
92 words
The power meter of Claim 1 further including: second test means for momentarily applying a predetermined second test signal to an input of said first converter means in lieu of said first product signal; third memory means for storing a second converted signal value which corresponds to said second test signal; and third comparator means for producing a third error signal when said first converted signal differs from said stored second converted signal value more than a predetermined amount when said second test signal is applied to said first converter means input.
Claim 6
Dependent Claim
31 words
The power metering system of Claim 4 wherein said first converter means utilizes a first reference voltage and wherein said second test signal is derived independent of said first reference voltage.
Claim 7
Dependent Claim
184 words
The power metering system of Claim 5 wherein said power meter further includes: delay means for producing a delayed first modulated signal delayed a predetermined period of time with respect to said first modulated signal; second multiplying means for producing a second product signal, from said delayed modulated signal and said second analog signal, which is indicative of power carried on the line; second converter means for producing a second converted signal from said second product signal in the form of a train of pulses, with each of said pulses representing a predetermined amount of power carried on the line; third test means for momentarily applying a predetermined third test signal to an input of said second converter means in lieu of said second product signal; fourth memory means for storing a third converted signal value which corresponds to said third test signal; and fourth comparator means for producing a fourth error signal when said second converted signal differs from said stored third converted signal value more than a predetermined amount when said third test signal is applied to said second converter means input.
Claim 8
Dependent Claim
42 words
The power meter of Claim 6 wherein said second converter means utilizes a second reference voltage having a polarity opposite to that of said first reference voltage reference and wherein said third test signal is derived independent of said second reference voltage.
Claim 9
Dependent Claim
29 words
The power meter of Claims 7 wherein said first and second voltage references are of opposite polarity and wherein said second and third test signals are of opposite polarity.
Claim 10
Dependent Claim
181 words
An electrical power meter having internal self-test capabilities comprising: monitoring means for producing a first signal indicative of one of voltage and current carried on a line and a second signal indicative of the other of voltage and current on the line; first multiplying means for producing a first product signal comprised of a series of pulses having a pulse width which corresponds to said first signal and a pulse height which corresponds to said second signal; first converter means for producing a first converted signal from said first product signal indicative of power carried on the line; first test means for momentarily applying a predetermined first test signal to an input of said first converter means in lieu of said first product signal; first memory means for storing a first converted signal value which corresponds to said first test signal; and first comparator means for producing a first error signal when said first converted signal differs from said stored first converted signal value more than a predetermined amount when said first test signal is applied to said first converter means.
Claim 11
Dependent Claim
181 words
An electrical power meter having internal self-test capabilities comprising: monitoring means for producing a first signal indicative of one of voltage and current carried on a line and a second signal indicative of the other of voltage and current on the line; first multiplying means for producing a first product signal comprised of a series of pulses having a pulse width which corresponds to said first signal and a pulse height which corresponds to said second signal; first converter means for producing a first converted signal from said first product signal indicative of power carried on the line; first test means for momentarily applying a predetermined first test signal to an input of said first converter means in lieu of said first product signal; first memory means for storing a first converted signal value which corresponds to said first test signal; and first comparator means for producing a first error signal when said first converted signal differs from said stored first converted signal value more than a predetermined amount when said first test signal is applied to said first converter means.
Claim 12
Dependent Claim
150 words
The power meter of Claim 9 further including: second multiplying means for producing a second product signal comprised of a series of pulses having a pulse width which corresponds to said first signal delayed in time and a pulse height which corresponds to said second signal; second converter means for producing a second converted signal from said second product signal indicative of power carried on the line; second test means for momentarily applying a predetermined second test signal to an input of said second converter means in lieu of said second product signal; second memory means for storing a second converted signal value which corresponds to said second test signal; and second comparator means for producing a second error signal when said second converted signal differs from said stored second converted signal value more than a predetermined amount when said second test signal is applied to said second converter means.
Claim 13
Dependent Claim
32 words
The power meter of Claim 10 wherein said first and second converter means both utilize reference voltages of opposite polarity and wherein said first and second test signals are of opposite polarity.
Claim 14
Dependent Claim
20 words
The power meter of Claim 11 wherein said first and second test signals are derived independent of said reference voltages.
Claim 15
Dependent Claim
112 words
The power meter of Claim 11 further including: first modulator means for producing a first modulated signal changeable between two levels and indicative of the magnitude of said first signal; third test means for momentarily applying a predetermined third test signal to an input of said first modulator means in lieu of said first signal; third memory means for storing a first modulated signal value which corresponds to said third test signal; and third comparator means for producing a third error signal when said first modulated signal differs from said stored first modulated signal value more than a predetermined amount when said third test signal is applied to said first modulator means.
Claim 16
Dependent Claim
120 words
The power meter of claim 13 further including: fourth memory means for storing a third converted signal value which corresponds to said third test signal; fifth memory means for storing a fourth converted signal value which corresponds to said third test signal; fourth compartor means for producing a fourth error signal when said first converted signal differs from said stored third converted signal value more than a predetermined amount when said third test signal is applied to said first modulator means; and fifth comparator means for producing a fifth error signal when said second converted signal differs from said fourth converted signal value more than a predetermined amount when said third test signal is applied to said first modulator means.
References Cited (Backward Citations)
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