Patent US3723825A successfully refreshed from Google Patents.
US3723825A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnet controller
Assignee: Schneider Electric USA Inc
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Filing: 1972-01-19
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Granted: 1973-03-27
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Expires: 1992-01-19
Abstract
Abstract A control system for a lifting magnet measures the lift current of the magnet and causes the drop-out current to reach a predetermined percentage of the lift current at interruption so that clean drops are provided, without adjustment, regardless of the condition of the circuit elements, the temperature of the lifting magnet, or the size of the magnet.
Inventors
- 👤 Viney T De
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 13:02
CPC Classifications
H; H01; H01F; H01F13/00; B; B66; B66C; B66C1/00; B66C1/04; B66C1/06; B66C1/08; B66C13/00; B66C13/18; H01F7/00; H01F7/06; H01F7/08; H01F7/18; B66C2700/00; B66C2700/08; B66C2700/087
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
125 words
In a control system for selectively connecting and disconnecting an electromagnet to and from a source of power, said control system comprising switching means for selectively connecting and disconnecting the electromagnet directly to and from the source of power to control the flow of a lift current through the electromagnet, resistance means, and reverse switching means for connecting the electromagnet to the source through the resistance means to cause a reverse current to flow through the electromagnet upon cessation of the lift current, the improvement comprising control means for measuring the lift current, measuring the reverse current, and causing cessation of the reverse current through the electromagnet when the magnitude of the reverse current bears a predetermined relationship to the magnitude of the lift current.
Claim 2
Dependent Claim
125 words
In a control system for selectively connecting and disconnecting an electromagnet to and from a source of power, said control system comprising switching means for selectively connecting and disconnecting the electromagnet directly to and from the source of power to control the flow of a lift current through the electromagnet, resistance means, and reverse switching means for connecting the electromagnet to the source through the resistance means to cause a reverse current to flow through the electromagnet upon cessation of the lift current, the improvement comprising control means for measuring the lift current, measuring the reverse current, and causing cessation of the reverse current through the electromagnet when the magnitude of the reverse current bears a predetermined relationship to the magnitude of the lift current.
Claim 3
Dependent Claim
56 words
A control system as in claim 1 wherein said reverse switching means includes a drop contact which closes upon operation of said Reverse switching means and said switching means includes a lift contact which opens after the drop contact closes, and said control means includes means for measuring the lift current after the lift contact opens.
Claim 4
Dependent Claim
41 words
A control system as in claim 1 wherein said control means includes means for causing cessation of the reverse current through the electromagnet when the magnitude of the reverse current reaches a predetermined percentage of the magnitude of the lift current.
Claim 5
Dependent Claim
42 words
A control system as in claim 1 wherein said control means includes means responsive to one voltage across the resistance means for measuring said lift current and means responsive to an other voltage across the resistance means for measuring said reverse current.
Claim 6
Dependent Claim
42 words
A control system as in claim 4 wherein said resistance means includes a first portion and a second portion, said one voltage responsive means is connected across said first portion and said other voltage responsive means is connected across said second portion.
Claim 7
Dependent Claim
94 words
A control system as in claim 4 wherein said means responsive to said one voltage includes storage means for storing a first voltage proportional to the magnitude of the lift current and said control means includes comparison means for comparing a second voltage proportional to the magnitude of the reverse current with said first voltage, means responsive to the comparison means for producing an operating signal when said second voltage bears a predetermined relationship to said first voltage, and terminating means responsive to the operating signal for interrupting the reverse current through the electromagnet.
Claim 8
Dependent Claim
14 words
A control system as in claim 6 wherein said storage means is a capacitor.
Claim 9
Dependent Claim
107 words
A control system as in claim 4 wherein said means responsive to said one voltage includes storage means for storing a first voltage proportional to the magnitude of the lift current and said control means includes comparison means for comparing a second voltage proportional to the magnitude of the reverse current with said first voltage and means responsive to the comparison means for producing an operating signal dependent upon the relationship said second voltage bears to said first voltage, and terminating means responsive to the operating signal for interrupting the reverse current through the electromagnet when a predetermined relationship between the first and second voltages is reached.
Claim 10
Dependent Claim
14 words
A control system as in claim 8 wherein said storage means is a capacitor.
Claim 11
Dependent Claim
132 words
A control system as in claim 8 wherein said control means includes timing means activated to initiate a timing cycle upon connection of the electromagnet to the source through said resistance means by said reverse switching means and operative to produce an operating signal after a time delay, and overlap means activated to initiate a timing cycle when the electromagnet is connected directly to the source of power by said switching means while connected to the source through said resistance means by said reverse switching means and operative to produce an operating signal after a time delay, and wherein said terminating means is responsive to each of the operating signal of the timing means and the operating signal of the overlap means for stopping the flow of reverse current through the electromagnet.
Claim 12
Independent Claim
78 words
The method of demagnetizing an electromagnet connected to a source of power to apply a lift voltage causing a lift current to flow through the electromagnet, said method comprising the steps of terminating application of the lift voltage, applying reverse voltage to the magnet to produce a reverse current in the electromagnet in a direction opposite that of the lift current, and disconnecting the reverse voltage when the reverse current bears a predetermined relationship to the lift current.
Claim 13
Independent Claim
78 words
The method of demagnetizing an electromagnet connected to a source of power to apply a lift voltage causing a lift current to flow through the electromagnet, said method comprising the steps of terminating application of the lift voltage, applying reverse voltage to the magnet to produce a reverse current in the electromagnet in a direction opposite that of the lift current, and disconnecting the reverse voltage when the reverse current bears a predetermined relationship to the lift current.
Claim 14
Independent Claim
101 words
A method of demagnetizing an electromagnet connected to a source of power to apply a lift voltage causing a lift current to flow through the electromagnet, said method comprising the steps of terminating applicatIon of the lift voltage, storing a first voltage proportional to lift current, applying reverse voltage to the electromagnet to produce a reverse current in the magnet in a direction opposite that of the lift current, providing a second voltage proportional to the reverse current, comparing said first and second voltages, and disconnecting the reverse voltage when the first voltage bears a predetermined relationship to the second voltage.
Claim 15
Independent Claim
101 words
A method of demagnetizing an electromagnet connected to a source of power to apply a lift voltage causing a lift current to flow through the electromagnet, said method comprising the steps of terminating applicatIon of the lift voltage, storing a first voltage proportional to lift current, applying reverse voltage to the electromagnet to produce a reverse current in the magnet in a direction opposite that of the lift current, providing a second voltage proportional to the reverse current, comparing said first and second voltages, and disconnecting the reverse voltage when the first voltage bears a predetermined relationship to the second voltage.
References Cited (Backward Citations)
US3368119A
Cited
US3579053A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-03-26 | 1976-09-25 | 1977-03-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-03-26 | 1980-09-25 | 1981-03-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-03-26 | 1984-09-25 | 1985-03-27 | $7700.00 | Window Closed / Lapsed |