US3671860A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Maximum current indicator for electrical apparatus
Assignee: General Electric Co
•
Filing: 1969-10-24
•
Granted: 1972-06-20
•
Expires: 1989-10-24
Abstract
Abstract A maximum current indicator to monitor the current flow in an electrical apparatus. A facsimile of load current from a current transformer is applied to a heater resistor. A sensor resistor having a high positive temperature coefficient is coupled to the heater such that the steady state temperature of the sensor is directly proportional to the power dissipated in the heater, making such temperature a function of the facsimile load current. The sensor resistor is part of a voltage divider network which includes a rheostat, the voltage across such divider being determined by a Zener diode. The divider output voltage at a junction thereof is determined by the sensor resistor and the rheostat. A pair of transistors are arranged in an emitter coupled binary circuit whose conduction states are determined by the voltage at the junction of the divider network. An isolation transformer and a silicon controlled rectifier form a switching circuit which is actuated by the binary circuit. A motor is controlled by the switch, the motor acting to set an indicator dial and also to drive the rheostat to a position for resetting of the binary circuit.
Inventors
- 👤 Clarence J Kettler
- 👤 Clifford L Downs
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 13:37
CPC Classifications
G; G01; G01R; G01R19/00; G01R19/30
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
346 words
A maximum current indicator for indicating the maximum current flow in an electrical apparatus comprising in combination a. a heater member connected to be heated proportional to the current flow in an electrical apparatus, b. a sensor resistor having a positive temperature coefficient, 1. said sensor resistor thermally coupled to said heater, c. a voltage divider network including said sensor resistor, a rheostat and at least another resistor, 1. a junction in said voltage divider having said sensor resistor and said rheostat on one side and said at least another resistor on the other side, d. means for maintaining a constant voltage across said voltage divider, e. a pair of transistors coupled to form an emitter coupled binary circuit, 1. said junction of said voltage divider electrically connected to the base of one of said pair of transistors, 2. the voltage at said junction normally being below the threshold voltage of said one transistor whereby said one transistor is non-conducting and the other of said pair of transistors is conducting, f. an electric motor connected to a source of electrical energy, g. a switch means connected between one side of said motor and said source of electrical energy, 1. said switch normally being open such that said motor is deenergized when said other transistor is conducting and said switch being closed to energize said motor when said other transistor is non-conducting, h. a current indicator connected to the drive shaft of said motor to be driven upscale when said motor is energized, 1. a mechanical coupling between said dial and said rheostat to move said rheostat when said dial is moved, a rise in temperature of said heater in response to an increase in current of the electrical apparatus increasing the resistance of said sensor thereby increasing the voltage at said junction to turn on said one transistor and turn off said other transistor to energize said motor and drive said dial upscale, movement of said scale adjusting said rheostat to decrease the voltage of said junction turning off said one transistor and de-energizing said motor.
Claim 2
Dependent Claim
346 words
A maximum current indicator for indicating the maximum current flow in an electrical apparatus comprising in combination a. a heater member connected to be heated proportional to the current flow in an electrical apparatus, b. a sensor resistor having a positive temperature coefficient, 1. said sensor resistor thermally coupled to said heater, c. a voltage divider network including said sensor resistor, a rheostat and at least another resistor, 1. a junction in said voltage divider having said sensor resistor and said rheostat on one side and said at least another resistor on the other side, d. means for maintaining a constant voltage across said voltage divider, e. a pair of transistors coupled to form an emitter coupled binary circuit, 1. said junction of said voltage divider electrically connected to the base of one of said pair of transistors, 2. the voltage at said junction normally being below the threshold voltage of said one transistor whereby said one transistor is non-conducting and the other of said pair of transistors is conducting, f. an electric motor connected to a source of electrical energy, g. a switch means connected between one side of said motor and said source of electrical energy, 1. said switch normally being open such that said motor is deenergized when said other transistor is conducting and said switch being closed to energize said motor when said other transistor is non-conducting, h. a current indicator connected to the drive shaft of said motor to be driven upscale when said motor is energized, 1. a mechanical coupling between said dial and said rheostat to move said rheostat when said dial is moved, a rise in temperature of said heater in response to an increase in current of the electrical apparatus increasing the resistance of said sensor thereby increasing the voltage at said junction to turn on said one transistor and turn off said other transistor to energize said motor and drive said dial upscale, movement of said scale adjusting said rheostat to decrease the voltage of said junction turning off said one transistor and de-energizing said motor.
Claim 3
Dependent Claim
59 words
the voltage at said junction normally being below the threshold voltage of said one transistor whereby said one transistor is non-conducting and the other of said pair of transistors is conducting, f. an electric motor connected to a source of electrical energy, g. a switch means connected between one side of said motor and said source of electrical energy,
Claim 4
Dependent Claim
59 words
the voltage at said junction normally being below the threshold voltage of said one transistor whereby said one transistor is non-conducting and the other of said pair of transistors is conducting, f. an electric motor connected to a source of electrical energy, g. a switch means connected between one side of said motor and said source of electrical energy,
Claim 5
Dependent Claim
56 words
A maximum current indicator as claimed in claim 1 in which said switch means comprises an isolation transformer and a silicon controlled rectifier, the primary of said transformer in circuit with said motor and the secondary of said tranSformer in circuit with said rectifier, and the gate of said rectifier electrically connected to said other transistor.
Claim 6
Dependent Claim
25 words
and a mechanical connection between said indicator and said rheostat whereby said rheostat is driven by said indicator to decrease said voltage at said junction.
Claim 7
Dependent Claim
25 words
and a mechanical connection between said indicator and said rheostat whereby said rheostat is driven by said indicator to decrease said voltage at said junction.
Claim 8
Dependent Claim
34 words
A maximum current indicator as claimed in claim 1 in which said means for maintaining a constant voltage across said voltage divider includes a Zener diode connected in parallel circuit with said voltage divider.
Claim 9
Dependent Claim
75 words
A maximum current indicator as claimed in claim 1 in which temperature compensation is provided by a plurality of resistors connected in said voltage divider, where said at least another resistor has a positive temperature coefficient and has in parallel circuit a temperature insensitive resistor, and a negative temperature coefficient resistor is connected in parallel circuit with said sensor resistor with a temperature insensitive resistor connected in parallel circuit with said negative temperature coefficient resistor.
Claim 10
Dependent Claim
47 words
A maximum current indicator for indicating the maximum current flow in an electrical apparatus, comprising in combination; a. a sensor resistor heated proportional to the current flow in the electrical apparatus, b. a voltage divider network including a rheostat, said sensor resistor, and at least another resistor,
Claim 11
Dependent Claim
47 words
A maximum current indicator for indicating the maximum current flow in an electrical apparatus, comprising in combination; a. a sensor resistor heated proportional to the current flow in the electrical apparatus, b. a voltage divider network including a rheostat, said sensor resistor, and at least another resistor,
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-06-20 | 1975-12-20 | 1976-06-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-06-20 | 1979-12-20 | 1980-06-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-06-20 | 1983-12-20 | 1984-06-20 | $7700.00 | Window Closed / Lapsed |