US6226166B1
Expired / Lapsed
US
⏱️ 0.0 years remaining
Transient overvoltage and lightning protection of power connected equipment
Assignee: Erico Lightning Technologies Pty Ltd
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Filing: 1997-11-28
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Granted: 2001-05-01
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Expires: 2017-11-28
Abstract
Abstract An overvoltage protection circuit is provided for protecting electrical equipment from transients on power lines ( 41, 42 ). The circuit has a string of series-connected silicon avalanche diodes (SADs) ( 40 )connected across the power lines ( 41, 42 ) to provide an initial clamping threshold before energy-absorbing modules ( 43 a , 43 b , 43 c ) come on line to provide secondary clamping. The modules ( 43 a , 43 b , 43 c ) include a number of metal oxide varistors (MOVs) ( 44 ) connected in parallel and a switching device in the form of a gas arrester ( 45 ) connected in series with the MOVs ( 44 ). A resistance ( 46 ) is connected in parallel with the gas arrester ( 45 ) to form a high pass filter with the natural capacitance of the MOVs ( 44 ). This maintains the voltage across the resistance ( 46 ) well below the switch operating level during normal conditions and enables a component such as a 230 V fast acting gas arrester ( 45 ) to be used. In an alternative embodiment, the gas arrester ( 45 ) may be replaced by a solid state switch, such as a Sidator or a Triac.
Inventors
- 👤 John Richard Gumley
- 👤 Christopher John Kossmann
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 20:03
CPC Classifications
H; H02; H02H; H02H9/00; H02H9/04; H02H9/06
Claims Analysis
Total Claims: 33
Claim 1
Independent Claim
78 words
An overvoltage protection circuit comprising: at least one energy-absorbing module, said energy absorbing module including: at least one metal oxide varistor (MOV); a switching device connected in series with said at least one MOV; and a resistance or impedance connected in parallel with said switching device, said resistance or impedance forming a high pass filter with capacitance of the at least one MOV, wherein said switching device is configured to turn on in a presence of a transient.
Claim 2
Dependent Claim
78 words
An overvoltage protection circuit comprising: at least one energy-absorbing module, said energy absorbing module including: at least one metal oxide varistor (MOV); a switching device connected in series with said at least one MOV; and a resistance or impedance connected in parallel with said switching device, said resistance or impedance forming a high pass filter with capacitance of the at least one MOV, wherein said switching device is configured to turn on in a presence of a transient.
Claim 3
Dependent Claim
16 words
A circuit according to claim 1 wherein said high pass filter further includes a non-linear element.
Claim 4
Dependent Claim
18 words
A circuit according to claim 2 wherein said non-linear element comprises back-to-back zener diodes or an avalanche diode.
Claim 5
Dependent Claim
19 words
A circuit according to claim 1 wherein a capacitance is connected in parallel with the at least one MOV.
Claim 6
Dependent Claim
32 words
A circuit according to claim 1 wherein said energy absorbing module includes a plurality of MOVs connected in parallel, said switching device being connected in series with the plurality of paralleled MOVs.
Claim 7
Dependent Claim
22 words
A circuit according to claim 1 further including a plurality of series-connected avalanche diodes to be connected across an a.c. power supply.
Claim 8
Dependent Claim
22 words
A circuit according to claim 6 wherein the series-connected avalanche diodes are connected in parallel with the at least one energy-absorbing module.
Claim 9
Dependent Claim
35 words
A circuit according to claim 6 wherein the series-connected avalanche diodes are connected in parallel with the switching device and in series with said at least one MOV of the at least one energy-absorbing module.
Claim 10
Dependent Claim
18 words
A circuit according to claim 7 wherein a resistance is connected in series with the series-connected avalanche diodes.
Claim 11
Dependent Claim
18 words
A circuit according to claim 7 wherein a switching component is connected in series with the series-connected avalanche-diodes.
Claim 12
Dependent Claim
35 words
A circuit according to claim 10 wherein an impedance is connected in parallel with the switching component and a capacitance is connected in parallel with the series-connected avalanche diodes to form a high pass filter.
Claim 13
Dependent Claim
18 words
A circuit according to claim 6 wherein the series-connected avalanche diodes are low voltage silicon avalanche diodes (SADs).
Claim 14
Dependent Claim
28 words
A circuit according to claim 6 wherein the series-connected avalanche diodes are arranged to provide an initial clamping threshold above the peak voltage of the a.c. power supply.
Claim 15
Dependent Claim
27 words
A circuit according to claim 13 wherein, for an a.c. power supply of 220-240V r.m.s. the series-connected avalanche diodes provide an initial clamping threshold of about 400V.
Claim 16
Dependent Claim
35 words
A circuit according to claim 1 wherein the at least one MOV has an a.c. voltage rating less than the r.m.s. voltage of an a.c. power supply across which the overvoltage protection circuit is connected.
Claim 17
Dependent Claim
35 words
A circuit according to claim 15 wherein for an a.c. power supply of 220-240V r.m.s. the at least one MOV has a voltage rating falling substantially within the range from 150V a.c to 230V a.c.
Claim 18
Dependent Claim
36 words
A circuit according to claim 1 wherein the switching device comprises a solid state switch, and the solid state switch has a minimum switching threshold of about 140V and a maximum switching threshold of about 220V.
Claim 19
Dependent Claim
24 words
A circuit according to claim 17 wherein the solid state switch is a Sidactor, a Triac or at least one silicon controlled rectifier (SCR).
Claim 20
Dependent Claim
14 words
A circuit according to claim 1 wherein the switching device comprises a gas arrester.
Claim 21
Dependent Claim
32 words
A circuit according to claim 19 wherein the gas arrester has a sparkover voltage of less than the peak voltage of an a.c. power supply across which the overvoltage circuit is connected.
Claim 22
Independent Claim
112 words
A method of protecting electrical equipment from overvoltages caused by transients on power lines of an a.c. power supply including the steps of: connecting at least one metal oxide varistor (MOV) across power lines to absorb energy from a transient; connecting a switching device in series with said at least one MOV to isolate said at least one MOV from the a.c. power supply in the absence of a transient on the power lines and to turn on in the presence of a transient; and connecting a resistance or impedance in parallel with said switching device so as to form a high pass filter with capacitance of the at least one MOV.
Claim 23
Independent Claim
112 words
A method of protecting electrical equipment from overvoltages caused by transients on power lines of an a.c. power supply including the steps of: connecting at least one metal oxide varistor (MOV) across power lines to absorb energy from a transient; connecting a switching device in series with said at least one MOV to isolate said at least one MOV from the a.c. power supply in the absence of a transient on the power lines and to turn on in the presence of a transient; and connecting a resistance or impedance in parallel with said switching device so as to form a high pass filter with capacitance of the at least one MOV.
Claim 24
Dependent Claim
35 words
A circuit according to claim 6 wherein a first fuse is connected in series with said plurality of series-connected avalanche diodes and a second fuse is connected in series with said at least one MOV.
Claim 25
Dependent Claim
68 words
A circuit according to claim 22 wherein said first and second fuses are formed by fuse tracks on a printed circuit board, said fuse tracks are covered by an insulating film, a continuous line of conductive ink is provided on the insulating film over the fuse tracks, and the line of conductive ink is connected to a sensing circuit for detecting operation of the first or second fuse.
Claim 26
Independent Claim
102 words
A method of protecting electrical equipment from overvoltages caused by transients on power lines of an a.c. power supply including the steps of: connecting at least one metal oxide varistor (MOV) across power lines to absorb energy from a transient; connecting a switching device in series with said at least one MOV to isolate said at least one MOV from the a.c. power supply in the absence of a transient on the power lines; and connecting a resistance or impedance in parallel with said switching device so as to form a high pass filter with capacitance of the at least one MOV.
Claim 27
Independent Claim
102 words
A method of protecting electrical equipment from overvoltages caused by transients on power lines of an a.c. power supply including the steps of: connecting at least one metal oxide varistor (MOV) across power lines to absorb energy from a transient; connecting a switching device in series with said at least one MOV to isolate said at least one MOV from the a.c. power supply in the absence of a transient on the power lines; and connecting a resistance or impedance in parallel with said switching device so as to form a high pass filter with capacitance of the at least one MOV.
Claim 28
Dependent Claim
33 words
A method according to claim 24 including the step of connecting a plurality of series-connected avalanche diodes in parallel with the switching device to provide high speed clamping at an initial clamping voltage.
Claim 29
Dependent Claim
41 words
A method according to claim 25 wherein the switching device is arranged to connect the at least one MOV to the power lines to provide secondary clamping when a triggering voltage induced by a transient on the power lines is reached.
Claim 30
Dependent Claim
49 words
A method according to claim 26 wherein the switching device is arranged to disconnect the at least one MOV at the end of a transient, and wherein the secondary clamping takes place at a clamping voltage higher than the initial clamping voltage of the plurality of series-connected avalanche diodes.
Claim 31
Dependent Claim
37 words
A method according to claim 27 wherein, for an a.c. power supply of 220-240V r.m.s. the initial clamping voltage is approximately 400V, and wherein the secondary clamping voltage falls substantially within the range from 420V to 530V.
Claim 32
Dependent Claim
39 words
A method according to claim 28 wherein a capacitance is connected in parallel with said at least one MOV to supplement the inherent capacitance of said at least one MOV, and wherein the switching device comprises a gas arrester.
Claim 33
Dependent Claim
87 words
A method according to claim 29 wherein the switching device comprises a solid state switch, such as a Sidactor, a Triac or at least one silicon controlled rectifier (SCR), wherein a plurality of energy absorbing stages are connected in parallel with said series-connected avalanche diodes, each energy absorbing stage comprising a switching device connected in series with at least one metal oxide varistor (MOV), and wherein a plurality of MOVs are connected in parallel and said switching device is connected in series with said plurality of MOVs.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2004-04-30 | 2004-10-30 | 2005-05-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2008-04-30 | 2008-10-30 | 2009-05-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2012-04-30 | 2012-10-30 | 2013-05-01 | $7700.00 | Window Closed / Lapsed |