US3921070A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrical power monitor
Assignee: Automatic Switch Co
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Filing: 1972-09-01
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Granted: 1975-11-18
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Expires: 1992-09-01
Abstract
Abstract In a monitor for determining the real electrical power being delivered by a 3-phase source to a load, each phase voltage and a voltage which is proportional to and in phase with the corresponding line current are coupled to separate balanced detectors. Each detector provides a D.C. voltage which is proportional to the real power being delivered by its corresponding phase. The D.C. voltages from the balanced detectors are connected in series and the resulting sum voltage is coupled to a plurality of voltage comparators. Each voltage comparator provides a signal when the sum voltage exceeds a predetermined magnitude and each of the voltage comparators is set to respond to a different sum voltage magnitude. Since the sum voltage is proportional to the real power being delivered by the source, within the range of voltage magnitudes set, the output signals of the voltage comparators provide a measure of the power being delivered by the 3-phase source. A binary output means, such as a relay, is controlled by each comparator.
Inventors
- 👤 Ralph H Ringstad
- 👤 James M Daley
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 12:27
CPC Classifications
G; G01; G01R; G01R21/00; G01R21/133; G01R21/1331
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
137 words
A monitor for determining the real electrical power being delivered by an A.C. line to a load, comprising: a. means for providing a D.C. signal which is proportional to the product of A.C. line current, the corresponding A.C. line voltage, and the cosine of the phase difference between said line current and line voltage, b. means for providing a reference voltage which corresponds to a particular level of power being delivered by the A.C. source, and c. means for comparing the D.C. signal with said reference voltage and for providing a binary signal in response thereto, the binary signal indicating whether the magnitude of the D.C. signal is less than or greater than the reference voltage, thereby indicating whether the A.C. power being delivered to the load is less than or greater than said particular power level.
Claim 2
Dependent Claim
137 words
A monitor for determining the real electrical power being delivered by an A.C. line to a load, comprising: a. means for providing a D.C. signal which is proportional to the product of A.C. line current, the corresponding A.C. line voltage, and the cosine of the phase difference between said line current and line voltage, b. means for providing a reference voltage which corresponds to a particular level of power being delivered by the A.C. source, and c. means for comparing the D.C. signal with said reference voltage and for providing a binary signal in response thereto, the binary signal indicating whether the magnitude of the D.C. signal is less than or greater than the reference voltage, thereby indicating whether the A.C. power being delivered to the load is less than or greater than said particular power level.
Claim 3
Dependent Claim
19 words
A monitor as defined in claim 1 wherein said means for providing a D.C. signal includes a balanced detector.
Claim 4
Dependent Claim
70 words
A monitor as defined in claim 1 for use with an A.C. source which supplies polyphase power to the load, wherein said means for providing a D.C. signal includes an individual detector coupled to each phase of the A.C. source, each detector providing a D.C. output signal proportional to the power delivered by its respective phase, and means connecting said D.C. output signals in series to produce said D.C. signal.
Claim 5
Dependent Claim
24 words
A monitor as defined in claim 1 wherein the means for providing a reference voltage includes a power supply coupled to the A.C. source.
Claim 6
Dependent Claim
42 words
A monitor as defined in claim 1 including a binary output means controlled by said comparing means, the state of said binary output means indicating whether the power being delivered by the source is less or greater than said particular power level.
Claim 7
Dependent Claim
35 words
A monitor as defined in claim 5 wherein said binary indicator includes a relay having a pair of contacts, the states of said binary indicator being the open or closed circuits condition of said contacts.
Claim 8
Dependent Claim
117 words
A monitor as defined in claim 1 wherein said means for comparing the D.C. signal with said reference voltage includes a comparator comprising: a. a binary indicator; b. a programmable unijunction transistor having an anode, a cathode, and a gate; c. means coupling the gate to the reference voltage; d. means coupling the anode to the D.C. signal; and e. means coupling the cathode to the binary indicator, whereby when the magnitude of the D.C. signal exceeds the magnitude of the reference voltage the binary indicator is in one of its states and when the magnitude of the reference voltage exceeds the magnitude of the D.C. signal the binary indicator is in the other of its states.
Claim 9
Dependent Claim
35 words
A monitor as defined in claim 7 wherein said means for providing a reference voltage includes means for controlling the magnitude of the D.C. signal required to cause the binary indicator to change its state.
Claim 10
Dependent Claim
22 words
A monitor as defined in claim 7 wherein said means coupling the anode to the D.C. signal includes a Darlington transistor network.
Claim 11
Dependent Claim
56 words
A monitor as defined in claim 1 including means for providing a plurality of reference voltages each of which corresponds to a different particular level of power being delivered by the A.C. source, and a plurality of comparing means, each of said comparing means comparing said D.C. signal with a different one of said reference voltages.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-11-17 | 1979-05-19 | 1979-11-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-11-17 | 1983-05-19 | 1983-11-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-11-17 | 1987-05-19 | 1987-11-18 | $7700.00 | Window Closed / Lapsed |