US3878434A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Power-limiting electrical barrier device
Assignee: Leeds and Northrup Co
•
Filing: 1973-12-10
•
Granted: 1975-04-15
•
Expires: 1993-12-10
Abstract
Abstract The disclosed bipolar barrier device has two triacs for redundant over-voltage protection. These are made conductive when the output voltage exceeds the zener voltage of back-to-back zener diode strings. Thus, a failure constituting over-voltage is protected against even when another failure, such as failure of one triac, occurs. The same pair of triacs provide triple redundant protection against over-current when a third triac is added, for a current detecting resistor biases the third triac or one of the first pair to conduction when the current through the circuit exceeds the desired maximum. A current limiting resistor and a fuse are inserted in the input circuit and a capacitor connected across the input to absorb transient surges.
Inventors
- 👤 Ernst W Voorhoeve
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 14:06
CPC Classifications
H; H02; H02H; H02H9/00; H02H9/008
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
308 words
An electrical barrier for interconnecting an input between an input terminal and a grounded bus to an output between an output terminal and a grounded bus so that the power transmitted between the input and output is limited to a safe magnitude, comprising: an input lead for receiving a potential with respect to ground representative of the input, an output lead for providing a potential with respect to ground representative of the output, a pair of triacs each having one of its main terminals connected to said input lead and the other main terminal adapted for connection to said grounded bus, a series connected back-to-back zener diode string and isolating device for each of said triacs, said series circuits each being connected between said output lead and said other main terminal of each triac to allow current through said diode string only when the power signal exceeds the zener voltage of said diodes, means connecting the gate of each of said triacs to an associated one of said series circuits at a point such that said series connected device is between said gate and said output lead, whereby an excessive voltage causes the gate of one of the triacs to make the triac conductive so as to short circuit the input lead to ground, a third triac having one of its main terminals connected to said input lead and the other main terminal connected by a lead to means adapted for connection to said grounded bus, an isolating device connected between said output lead and the gate of said last named triac, and a current detecting resistor connecting said input and output leads, said resistor being of a value such that an excessive current flowing through it will cause the gate of one of said triacs to make it conductive to thereby short said input lead to ground.
Claim 2
Dependent Claim
308 words
An electrical barrier for interconnecting an input between an input terminal and a grounded bus to an output between an output terminal and a grounded bus so that the power transmitted between the input and output is limited to a safe magnitude, comprising: an input lead for receiving a potential with respect to ground representative of the input, an output lead for providing a potential with respect to ground representative of the output, a pair of triacs each having one of its main terminals connected to said input lead and the other main terminal adapted for connection to said grounded bus, a series connected back-to-back zener diode string and isolating device for each of said triacs, said series circuits each being connected between said output lead and said other main terminal of each triac to allow current through said diode string only when the power signal exceeds the zener voltage of said diodes, means connecting the gate of each of said triacs to an associated one of said series circuits at a point such that said series connected device is between said gate and said output lead, whereby an excessive voltage causes the gate of one of the triacs to make the triac conductive so as to short circuit the input lead to ground, a third triac having one of its main terminals connected to said input lead and the other main terminal connected by a lead to means adapted for connection to said grounded bus, an isolating device connected between said output lead and the gate of said last named triac, and a current detecting resistor connecting said input and output leads, said resistor being of a value such that an excessive current flowing through it will cause the gate of one of said triacs to make it conductive to thereby short said input lead to ground.
Claim 3
Dependent Claim
16 words
An electrical barrier as set forth in claim 1 in which said isolating devices are resistors.
Claim 4
Dependent Claim
51 words
An electrical barrier as set forth in claim 1 in which the said other main terminals of each of the three triacs is adapted for connection to a grounded bus by being connected to a threaded stud suitable for being secured to the grounded bus and to a circuit common lead.
Claim 5
Dependent Claim
43 words
An electrical barrier as set forth in claim 1 which includes a current limiting resistor in said input lead between said input terminal and the point at which said one of said main terminals of the triacs is connected to said input lead.
Claim 6
Dependent Claim
41 words
An electrical barrier as set forth in claim 1 which includes a fuse in said Input lead between said input terminal and the point at which said one of said main terminals of the triacs is connected to said input lead.
Claim 7
Dependent Claim
46 words
An electrical barrier as set forth in claim 1 which includes a fuse and a current limiting resistor in said input lead between said input terminals and the point at which said one of said main terminals of the triacs is connected to said input lead.
Claim 8
Dependent Claim
28 words
An electrical barrier as set forth in claim 6 which includes a capacitor connected between said input lead and a lead adapted for connection to said grounded bus.
Claim 9
Dependent Claim
305 words
An electrical barrier for interconnecting an input between an input terminal and a grounded bus to an output between an output terminal and a grounded bus so that the power transmitted between the input and output is limited to a safe magnitude, comprising: an input lead for receiving a potential with respect to ground representative of the input, an output lead for providing a potential with respect to ground representative of the output, a pair of triacs each having one of its main terminals connected to said input lead and the other main terminal adapted for connection to said grounded bus, a series connected zener diode and isolating device for each of said triacs, said series circuits each being connected between said output lead and said other main terminal of each triac to allow current through said diode only when the power signal exceeds the zener voltage of said diode, means connecting the gate of each of said triacs to an associated one of said series circuits at a point such that said series connected device is between said gate and said output lead, whereby an excessive voltage causes the gate of one of the triacs to make the triac conductive so as to short circuit the input lead to ground, a third triac having one of its main terminals connected to said input lead and the other main terminal connected by a lead to means adapted for connection to said grounded bus, an isolating device connected between said output lead and the gate of said last named triac, and a current detecting resistor connecting said input and output leads, said resistor being of a value such that an excessive current flowing through it will cause the gate of one of said triacs to make it conductive to thereby short said input lead to ground.
Claim 10
Dependent Claim
305 words
An electrical barrier for interconnecting an input between an input terminal and a grounded bus to an output between an output terminal and a grounded bus so that the power transmitted between the input and output is limited to a safe magnitude, comprising: an input lead for receiving a potential with respect to ground representative of the input, an output lead for providing a potential with respect to ground representative of the output, a pair of triacs each having one of its main terminals connected to said input lead and the other main terminal adapted for connection to said grounded bus, a series connected zener diode and isolating device for each of said triacs, said series circuits each being connected between said output lead and said other main terminal of each triac to allow current through said diode only when the power signal exceeds the zener voltage of said diode, means connecting the gate of each of said triacs to an associated one of said series circuits at a point such that said series connected device is between said gate and said output lead, whereby an excessive voltage causes the gate of one of the triacs to make the triac conductive so as to short circuit the input lead to ground, a third triac having one of its main terminals connected to said input lead and the other main terminal connected by a lead to means adapted for connection to said grounded bus, an isolating device connected between said output lead and the gate of said last named triac, and a current detecting resistor connecting said input and output leads, said resistor being of a value such that an excessive current flowing through it will cause the gate of one of said triacs to make it conductive to thereby short said input lead to ground.
Claim 11
Dependent Claim
16 words
An electrical barrier as set forth in claim 8 in which said isolating devices are resistors.
Claim 12
Dependent Claim
51 words
An electrical barrier as set forth in claim 8 in which the said other main terminals of each of the three triacs is adapted for connection to a grounded bus by being connected to a threaded stud suitable for being secured to the grounded bus and to a circuit common lead.
Claim 13
Dependent Claim
43 words
An electrical barrier as set forth in claim 8 which includes a current limiting resistor in said input lead between said input terminal and the point at which said one of said main terminals of the triacs is connected to said input lead.
Claim 14
Dependent Claim
41 words
An electrical barrier as set forth in claim 8 which includes a fuse in said input lead between said input terminal and the point at which said one of said main terminals of the triacs is connected to said input lead.
Claim 15
Dependent Claim
46 words
An electrical barrier as set forth in claim 8 which includes a fuse and a current limiting resistor in said input lead between said input terminals and the point at which said one of said main terminals of the triacs is connected to said input lead.
Claim 16
Dependent Claim
28 words
An electrical barrier as set forth in claim 13 which includes a capacitor connected between said input lead and a lead adapted for connection to said grounded bus.
References Cited (Backward Citations)
US3475653A
Cited
US3389301A
Cited
US3493815A
Cited
US3524997A
Cited
US3614539A
Cited
US3600634A
Cited
US3743860A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-04-14 | 1978-10-14 | 1979-04-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-04-14 | 1982-10-14 | 1983-04-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-04-14 | 1986-10-14 | 1987-04-15 | $7700.00 | Window Closed / Lapsed |