US3656136A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electric motor with safety sensing device
Assignee: M&B Electric Co Inc
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Filing: 1970-07-30
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Granted: 1972-04-11
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Expires: 1990-07-30
Abstract
Abstract A sensing device is connected to one of the winding terminals of an electric motor and a measure of the winding resistance is effectively determined by the value of current flowing through the terminal. If the winding resistance is too low for safe operation of the motor as might result from moisture in the motor, a control signal is generated by the sensing means which in turn will operate an indicating device to advise operators not to apply the main power source to the motor. The same control signal may be utilized to open a switch in the main powerline and thus prevent application of power of the motor until such time as the motor is in a safe condition for operation.
Inventors
- 👤 Darrell J Blair
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 23:41
CPC Classifications
H; H02; H02H; H02H11/00; H02H11/005; H02H11/002; H02H7/00; H02H7/08
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
226 words
An electric motor having multiple winDings; motor terminals on said windings; a control panel for connecting a main power source of a.c. electrical energy to said motor terminals; sensing means including an auxiliary source of electrical energy derived from said main power source and including a transformer and rectifying means, said sensing means being connected to one terminal of said motor terminals when said motor is disconnected from said main power source and responsive to a given current flow through said one terminal to generate a control signal in accordance with the resistance value of the windings connected to said one terminal; indicating means responsive to said control signal for advising operating personnel whether or not said motor is in a safe condition to apply the main power source to said motor; and control switch means between said main power source and said terminals including a relay responsive to said control signal to connect or disconnect said main power source to said motor terminals depending respectively on whether the resistance of said windings is such that said motor is in a safe or unsafe condition for operation, said sensing means including a current control means enabling adjustment of said given value of current for a given resistance value of said windings so that said sensing means can operate in combination with motors of different winding characteristics.
Claim 2
Dependent Claim
226 words
An electric motor having multiple winDings; motor terminals on said windings; a control panel for connecting a main power source of a.c. electrical energy to said motor terminals; sensing means including an auxiliary source of electrical energy derived from said main power source and including a transformer and rectifying means, said sensing means being connected to one terminal of said motor terminals when said motor is disconnected from said main power source and responsive to a given current flow through said one terminal to generate a control signal in accordance with the resistance value of the windings connected to said one terminal; indicating means responsive to said control signal for advising operating personnel whether or not said motor is in a safe condition to apply the main power source to said motor; and control switch means between said main power source and said terminals including a relay responsive to said control signal to connect or disconnect said main power source to said motor terminals depending respectively on whether the resistance of said windings is such that said motor is in a safe or unsafe condition for operation, said sensing means including a current control means enabling adjustment of said given value of current for a given resistance value of said windings so that said sensing means can operate in combination with motors of different winding characteristics.
References Cited (Backward Citations)
US2275883A
Cited
US3176219A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-04-11 | 1975-10-11 | 1976-04-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-04-11 | 1979-10-11 | 1980-04-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-04-11 | 1983-10-11 | 1984-04-11 | $7700.00 | Window Closed / Lapsed |