Patent US1330531A successfully refreshed from Google Patents.
US3376476A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ground detector for an induction heating installation
Assignee: Park Ohio Holdings Corp
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Filing: 1966-02-01
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Granted: 1968-04-02
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Expires: 1986-02-01
Abstract
No abstract record available.
Inventors
- 👤 Cecil P Porterfield
- 👤 James G Weit
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 14:53
CPC Classifications
H; H02; H02H; H02H3/00; H02H3/16; H02H3/17
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
224 words
A DEVICE FOR DE-ENERGIZING THE POWER SUPPLY OF AN INDUCTION HEATING INSTALLATION UPON THE APPEARANCE OF A GROUND ACROSS TWO SELECTED POINTS IN SAID INSTALLATION, SAID DEVICE COMPRISING: (A) A BRIDGE CIRCUIT HAVING TWO INPUT TERMINALS ADAPTED TO BE CONNECTED TO A SUPPLY OF D.C. VOLTAGE, FOUR INPEDANCE LEGS AND A NULL DETECTING INTERMEDIATE BRANCH SPACED FROM SAID TERMINALS BY SAID LEGS; (B) A RESISTOR ADJUSTED TO HAVE A RESISTANCE LEVEL CORRESPONDING TO THE MINIMUM ALLOWABLE RESISTANCE ACROSS SAID TWO POINTS, SAID RESISTOR BEING CONNECTED IN THE FIRST OF SAID LEGS; (C) THE ELECTRICAL CIRCUIT BETWEEN SAID TWO SELECTED POINTS BEING CONNECTED WITHIN THE SECOND OF SAID LEGS; (D) SAID FIRST AND SECOND LEGS BEING ARRANGED WITHIN SAID BRIDGE CIRCUIT SO THAT CURRENT WILL TEND TO FLOW THROUGH SAID BRANCH IN A FIRST DIRECTION WHEN THE RESISTANCE OF SAID SECOND LEG IS SUBSTANTIALLY ABOVE SAID MINIMUM ALLOWABLE LEVEL, CURRENT WILL TEND TO FLOW THROUGH SAID BRANCH IN A SECOND DIRECTION WHEN THE RESISTANCE OF SAID SECOND LEG IS SUBSTANTIALLY BELOW SAID MINIMUM ALLOWABLE LEVEL AND NO CURRENT WILL TEND TO FLOW THROUGH SAID BRANCH WHEN THE RESISTANCE IN SAID SECOND LEG IS APPROXIMATELY AT SAID MINIMUM ALLOWABLE LEVEL; AND, (E) MEANS IN SAID NULL DETECTING BRANCH FOR DE-ENERGIZING SAID POWER SUPPLY OF SAID INDUCTION HEATING INSTALLATION WHEN CURRENT FLOW THROUGH SAID BRANCH APPROACHES ZERO.
Claim 2
Independent Claim
224 words
A DEVICE FOR DE-ENERGIZING THE POWER SUPPLY OF AN INDUCTION HEATING INSTALLATION UPON THE APPEARANCE OF A GROUND ACROSS TWO SELECTED POINTS IN SAID INSTALLATION, SAID DEVICE COMPRISING: (A) A BRIDGE CIRCUIT HAVING TWO INPUT TERMINALS ADAPTED TO BE CONNECTED TO A SUPPLY OF D.C. VOLTAGE, FOUR INPEDANCE LEGS AND A NULL DETECTING INTERMEDIATE BRANCH SPACED FROM SAID TERMINALS BY SAID LEGS; (B) A RESISTOR ADJUSTED TO HAVE A RESISTANCE LEVEL CORRESPONDING TO THE MINIMUM ALLOWABLE RESISTANCE ACROSS SAID TWO POINTS, SAID RESISTOR BEING CONNECTED IN THE FIRST OF SAID LEGS; (C) THE ELECTRICAL CIRCUIT BETWEEN SAID TWO SELECTED POINTS BEING CONNECTED WITHIN THE SECOND OF SAID LEGS; (D) SAID FIRST AND SECOND LEGS BEING ARRANGED WITHIN SAID BRIDGE CIRCUIT SO THAT CURRENT WILL TEND TO FLOW THROUGH SAID BRANCH IN A FIRST DIRECTION WHEN THE RESISTANCE OF SAID SECOND LEG IS SUBSTANTIALLY ABOVE SAID MINIMUM ALLOWABLE LEVEL, CURRENT WILL TEND TO FLOW THROUGH SAID BRANCH IN A SECOND DIRECTION WHEN THE RESISTANCE OF SAID SECOND LEG IS SUBSTANTIALLY BELOW SAID MINIMUM ALLOWABLE LEVEL AND NO CURRENT WILL TEND TO FLOW THROUGH SAID BRANCH WHEN THE RESISTANCE IN SAID SECOND LEG IS APPROXIMATELY AT SAID MINIMUM ALLOWABLE LEVEL; AND, (E) MEANS IN SAID NULL DETECTING BRANCH FOR DE-ENERGIZING SAID POWER SUPPLY OF SAID INDUCTION HEATING INSTALLATION WHEN CURRENT FLOW THROUGH SAID BRANCH APPROACHES ZERO.
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) | 1971-04-02 | 1971-10-02 | 1972-04-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1975-04-02 | 1975-10-02 | 1976-04-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1979-04-02 | 1979-10-02 | 1980-04-02 | $7700.00 | Window Closed / Lapsed |