Patent US4099216A successfully refreshed from Google Patents.
US4099216A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fuseless intrinsic safety barrier
Assignee: Rosemount Inc
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Filing: 1976-11-12
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Granted: 1978-07-04
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Expires: 1996-11-12
Abstract
Abstract An encapsulated intrinsic safety electric barrier in which at least one positive temperature coefficient resistance device is embedded in the insulation together with the other electrical components of the module.
Inventors
- 👤 Lloyd E. Weberg
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 20:17
CPC Classifications
H; H02; H02H; H02H9/00; H02H9/008
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
223 words
In an intrinsic safety barrier circuit module having: a first pair of pole connectors adapted to be connected to an external power supply and to an external signal conditioning unit; and a second pair of pole connectors adapted to be connected to at least one input of an industrial process situated in a hazardous area; the combination of: a plurality of electrical components connected in circuit between said two pairs of pole connectors for conveying energy and information therebetween and for applying to said second pair of poles voltage and current of limited magnitude, said plurality including at least one positive temperature coefficient resistance device connected to one of said first pole connectors and operative in said module for limiting overcurrent from said connected one of said first pole under faulty conditions with said external power supply; with at least one of said electrical components being a voltage limiting device, said voltage limiting device being mounted in circuit after said one positive temperature coefficient resistance device, the time constant of said resistance device being smaller in response to an overcurrent than the time constant for which said voltage limiting device is exposed to destructive action by the same overcurrent; and with all of said electrical components of a plurality being encapsulated as a unit to form a fuseless intrinsic safety barrier circuit module.
Claim 2
Dependent Claim
223 words
In an intrinsic safety barrier circuit module having: a first pair of pole connectors adapted to be connected to an external power supply and to an external signal conditioning unit; and a second pair of pole connectors adapted to be connected to at least one input of an industrial process situated in a hazardous area; the combination of: a plurality of electrical components connected in circuit between said two pairs of pole connectors for conveying energy and information therebetween and for applying to said second pair of poles voltage and current of limited magnitude, said plurality including at least one positive temperature coefficient resistance device connected to one of said first pole connectors and operative in said module for limiting overcurrent from said connected one of said first pole under faulty conditions with said external power supply; with at least one of said electrical components being a voltage limiting device, said voltage limiting device being mounted in circuit after said one positive temperature coefficient resistance device, the time constant of said resistance device being smaller in response to an overcurrent than the time constant for which said voltage limiting device is exposed to destructive action by the same overcurrent; and with all of said electrical components of a plurality being encapsulated as a unit to form a fuseless intrinsic safety barrier circuit module.
References Cited (Backward Citations)
US3423636A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-07-03 | 1982-01-02 | 1982-07-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-07-03 | 1986-01-02 | 1986-07-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-07-03 | 1990-01-02 | 1990-07-04 | $7700.00 | Window Closed / Lapsed |