US3793560A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Resistive thermal protective device for inductances
Assignee: LIU YC
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Filing: 1973-06-18
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Granted: 1974-02-19
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Expires: 1993-06-18
Abstract
Abstract A resistance device for connection in a power lead of an inductance such as electromagnets, choke coils and transformers. The device is intended to be positioned in close proximity to the inductance and consists of a resistor of predetermined value connected in series with a short eutectic wire having a predetermined melting point positioned in intimate contact with the resistor and terminating in one conductor running to the source of electric energy. When the inductance is overloaded the temperature of the resistor will rise to a predetermined degree and melt the eutectic wire and open the circuit to the inductance.
Inventors
- 👤 J Schultheis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 20:37
CPC Classifications
H; H02; H02H; H02H5/00; H02H5/04; H02H5/047; H01; H01H; H01H85/00; H01H85/02; H01H85/0241; H01H2085/0008
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
215 words
A device for preventing damage or burn-out of an electric inductance means comprising a resistor of predetermined ohmic resistance and wattage having terminals at opposite ends thereof, a first conductor connecting one terminal of said resistor connected to one terminal of said inductance means and the opposite end of said inductance means for connection to one side of a source of electric energy, a eutectic wire of predetermined diameter and melting point with one end thereof connected to the remaining terminal of said resistor with the opposite end thereof connected to a second conductor for connection to the second side of said source of electric energy, a heat resistant insulating sleeve positioned over said connection of said eutectic wire and said second conductor for insulating same from a said resistor terminal, the entire resistor and eutectic wire and terminals and the heat resistant sleeve encased with a dielectric plastic material of substantially uniform thickness and positioned in contact with said inductance means whereby when said inductance is connected to a source of energy and a current above normal predetermined value is conducted through said inductance means the temperature of said resistor will raise to a predetermined degree sufficient to melt said eutectic wire and open the inductance circuit and prevent overload damage to said inductance.
Claim 2
Independent Claim
215 words
A device for preventing damage or burn-out of an electric inductance means comprising a resistor of predetermined ohmic resistance and wattage having terminals at opposite ends thereof, a first conductor connecting one terminal of said resistor connected to one terminal of said inductance means and the opposite end of said inductance means for connection to one side of a source of electric energy, a eutectic wire of predetermined diameter and melting point with one end thereof connected to the remaining terminal of said resistor with the opposite end thereof connected to a second conductor for connection to the second side of said source of electric energy, a heat resistant insulating sleeve positioned over said connection of said eutectic wire and said second conductor for insulating same from a said resistor terminal, the entire resistor and eutectic wire and terminals and the heat resistant sleeve encased with a dielectric plastic material of substantially uniform thickness and positioned in contact with said inductance means whereby when said inductance is connected to a source of energy and a current above normal predetermined value is conducted through said inductance means the temperature of said resistor will raise to a predetermined degree sufficient to melt said eutectic wire and open the inductance circuit and prevent overload damage to said inductance.
Claim 3
Dependent Claim
18 words
The construction recited in claim 1 whereby said resistor is of the carbon film type having calibrateD resistance.
Claim 4
Dependent Claim
26 words
The construction recited in claim 1 wherein the eutectic wire is an alloy of predetermined percentage of lead and tin and having a uniform predetermined diameter.
Claim 5
Dependent Claim
21 words
The construction recited in claim 1 wherein said insulating sleeve is made of woven fiberglass tubing of predetermined diameter and length.
Claim 6
Dependent Claim
22 words
The construction recited in claim 1 wherein said insulating sleeve is made of heat resistant ceramic tubing of predetermined diameter and length.
Claim 7
Dependent Claim
58 words
The construction recited in claim 1 whereby the assembly of the said resistor and the eutectic wire and the heat resistant insulation sleeve are covered with a length of P.V.C. heat shrinkable tubing of predetermined diameter and length and shrunk to close fit over all the elements of the device when predetermined heat is applied to the tubing.
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) | 1977-02-18 | 1977-08-20 | 1978-02-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-02-18 | 1981-08-20 | 1982-02-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-02-18 | 1985-08-20 | 1986-02-19 | $7700.00 | Window Closed / Lapsed |