US3617862A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Arcless load tap changing apparatus
Assignee: Allis Chalmers Corp
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Filing: 1969-12-31
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Granted: 1971-11-02
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Expires: 1989-12-31
Abstract
Abstract A load tap changing voltage regulator has a dial type tapchanging switch and an odd-even switch integral therewith having first and second pairs of contacts connected in series with first and second rotatable tap changer contacts forming first and second load circuits, and the odd-even switch contacts open before the corresponding tap changer rotatable contact disengages a stationary contact and close after it engages a succeeding stationary contact. A pair of oppositely poled thyristors are connected across the first and second load circuits. First and second current transformers are connected in the first and second load circuits and energize bridge rectifiers which supply gating current to the thyristors and also indicate whether the load circuits are open or closed. RC time delay circuits responsive to the opening of either load circuit remove the gating signals to the thyristors after a predetermined time delay, thus assuring that the tap changer switch contacts and the odd-even switch contacts do not interrupt current and that the current is commutated off by the thyristors at current zero. Shunt regulators between the bridge rectifiers and the cathode-gate circuits of the thyristors regulate the power dissipation of the gate circuits, and the shunt control elements are biased in the active region to permit gating current to flow to the thyristors when both load circuits are closed and they are biased into saturation to shunt gating current from the thyristors a predetermined interval subsequent to the opening of either of the pairs of odd-even switch contacts.
Inventors
- 👤 Frederick A Stich
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 01:27
CPC Classifications
H; H01; H01F; H01F29/00; H01F29/02; H01F29/04
Claims Analysis
Total Claims: 31
Claim 1
Independent Claim
165 words
In a voltage regulator, the combination of a tap changer switch having a plurality of stationary contacts and first and second movable contacts adapted to sequentially engage said stationary contacts in both bridging and nonbridging positions, switch means having first and second pairs of normally closed contacts associated with and connected in series with said first and second movable contacts respectively with both connected to a load terminal forming first and second load circuits and having means to open each of said first and second pairs of contacts before its associated rotatable contact disengages from a stationary contact and to reclose it after said rotatable contact engages a succeeding stationary contact, controllable semiconductor means connected between said first and second load circuits, and means responsive to current flow in both of said load circuits for supplying a triggering signal to said semiconductor means and being responsive to the opening of either of said load circuits for removing said triggering signal after a predetermined time delay.
Claim 2
Dependent Claim
165 words
In a voltage regulator, the combination of a tap changer switch having a plurality of stationary contacts and first and second movable contacts adapted to sequentially engage said stationary contacts in both bridging and nonbridging positions, switch means having first and second pairs of normally closed contacts associated with and connected in series with said first and second movable contacts respectively with both connected to a load terminal forming first and second load circuits and having means to open each of said first and second pairs of contacts before its associated rotatable contact disengages from a stationary contact and to reclose it after said rotatable contact engages a succeeding stationary contact, controllable semiconductor means connected between said first and second load circuits, and means responsive to current flow in both of said load circuits for supplying a triggering signal to said semiconductor means and being responsive to the opening of either of said load circuits for removing said triggering signal after a predetermined time delay.
Claim 3
Dependent Claim
36 words
In a voltage regulator in accordance with claim 1 wherein said means for supplying a triggering signal includes first and second current transformers having their primary windings connected in said first and second load circuits respectively.
Claim 4
Dependent Claim
50 words
In a voltage regulator in accordance with claim 2 wherein said means for removing said triggering signal includes RC time delay means for connecting a low-impedance shunt across the input circuit to said controllable semiconductor means a predetermined interval after higher said first or said second current transformer is deenergized.
Claim 5
Dependent Claim
93 words
In a voltage regulator in accordance with claim 1 wherein said means for supplying a triggering signal and removing if after a time delay includes means coupled to at least one of said load circuits for deriving said triggering signal when current is flowing therein, means including a capacitor in series with a resistor connected to be charged from said signal deriving means and to supply said triggering signal after deenergization of said signal-deriving means, and means for cutting off said-triggering signal when the charge on said capacitor decays to a predetermined magnitude.
Claim 6
Dependent Claim
95 words
In a voltage regulator in accordance with claim 4 wherein said signal-deriving means includes transformer means and rectifier means coupled to at least one secondary winding of said transformer means, and said means for supplying a triggering signal also includes shunt voltage regulator means between said rectifier means and the input triggering circuit to said controllable semiconductor means and having a control element controllable semiconductor device in shunt to said input triggering circuit and wherein said means for cutting off said triggering signal biases said semiconductor device into saturation to cut off said triggering signal.
Claim 7
Dependent Claim
45 words
In a voltage regulator in accordance with claim 1 and including a reactor having first and second windings connected in said first and second load circuits respectively between said first and second movable contacts and the associated first and second pairs of switch means contacts.
Claim 8
Dependent Claim
36 words
In a voltage regulator in accordance with claim 1 wherein said controllable semiconductor means comprises a pair of oppositely pole thyristors and said means for applying a triggering signal supplies gating signals to both said thyristors.
Claim 9
Dependent Claim
63 words
In a voltage regulator in accordance with claim 1 wherein said stationary contacts are arranged in a circle and said movable contacts are rotatable and said tap changer switch has a rotatable member operatively connected to said first and second rotatable contacts and said rotatable member also controls opening and closing of said first and second pairs of contacts of said switch means.
Claim 10
Dependent Claim
42 words
In a voltage regulator in accordance with claim 8 wherein said switch means Includes a conductive switch plate having plurality of arcuately spaced radial projections and said rotatable member carries said first and second rotatable contacts and also carries said switch plate.
Claim 11
Dependent Claim
78 words
In a voltage regulator in accordance with claim 2 wherein said means for supplying a triggering signal also includes rectifier means between a secondary winding of at least one of said current transformers and the input-triggering circuit of said controllable semiconductor means and means including a capacitor in series with a resistor connected to be charged by said rectifier means for supplying said triggering signal for said predetermined time delay after opening of either of said load circuits.
Claim 12
Dependent Claim
69 words
In a voltage regulator in accordance with claim 10 wherein said means for removing said triggering signal includes triggering signal cutoff means for connecting a low-impedance shunt across the triggering input circuit of said controllable semiconductor means and means including-timing capacitor means for disabling said triggering signal cutoff means both when said rectifier means is energized an also when the voltage on said capacitor is above a predetermined magnitude.
Claim 13
Dependent Claim
76 words
In a voltage regulator in accordance with claim 7 wherein said means for supplying-gating signals also includes rectifier means between a secondary winding of at least one of said current transformers and the cathode-gate junctions of said thyristors and means including a capacitor in series with a resistor connected to be charged by said rectifier means for supplying-gating signals to said cathode-gate junctions for said predetermined time delay after opening of either of said load circuits.
Claim 14
Dependent Claim
105 words
In a voltage regulator in accordance with claim 12 wherein said rectifier means includes a plurality of bridge rectifiers and said means for supplying-gating signals after opening of either load circuit includes first and second storage capacitors each of which is connected in series with a resistor and to be charged by one of said bridge rectifiers, and said means for removing said gating signals includes gating signal cutoff means responsive to the deenergization of either of said first or said second current transformer for connecting a low-impedance shunt across the cathode-gate junction of each of said thyristors said predetermined time delay after said deenergization.
Claim 15
Dependent Claim
109 words
In a voltage regulator in accordance with claim 13 wherein said gating signal cutoff means includes first and second RC time delay circuit means associated with each of said thyristors and including the series arrangement of a resistor and a timing capacitor and being connected to be charged from bridge rectifiers energized from secondary windings of said first and second current transformers respectively, said gating signal cutoff means being operable to connect said low-impedance shunt in response to the decay of the voltage across the timing capacitor of said first or said second RC circuit means to a predetermined magnitude incident to the deenergization of the corresponding current transformer.
Claim 16
Dependent Claim
69 words
In a voltage regulator in accordance with claim 14 wherein said means for supplying a triggering signal includes a shunt voltage regulator between the cathode-gate junction of each of said thyristors and one of said bridge rectifiers having a control element transistor in shunt to said cathode-gate junction, and said gating signal cutoff means is operable to bias said control element transistor of each said shunt regulator into saturation.
Claim 17
Dependent Claim
60 words
In a voltage regulator in accordance with claim 1 and including the series arrangement of a protective spark gap and a resistance connected across the series arrangement of said first and second pairs of switch means contacts, whereby said controllable semiconductor means is triggered into conduction if a transient occurs having sufficient energy to break down said protective spark gap.
Claim 18
Dependent Claim
46 words
In a voltage regulator in accordance with claim 10 wherein said means for supplying a trigGering signal includes shunt voltage regulator means between said rectifier means and said input triggering circuit of said controllable rectifier means to limit the power dissipation in said input triggering circuit.
Claim 19
Dependent Claim
62 words
In a voltage regulator in accordance with claim 17 wherein said shunt regulator means includes a control element transistor in shunt to said input triggering circuit of said controllable semiconductor means and said capacitor means includes RC time delay means for biasing said control element transistor into saturation said predetermined delay after deenergization of either said first or said second current transformer.
Claim 20
Dependent Claim
192 words
In a voltage regulator, the combination of a tap changer switch having a plurality of stationary contacts and first and second movable contacts adapted to sequentially engage said stationary contacts in both bridging and nonbridging positions and to alternately move between stationary contacts, switch means having first and second pairs of normally closed contacts associated with and connected in series with said first and second movable contacts respectively forming first and second load circuits and having means to open each of said first and second pair of contacts before its associated movable contact disengages from a stationary contact and to reclose it after said movable contact engages a succeeding stationary contact, controllable semiconductor means connected between said first and second load circuits, and means for applying a triggering signal to said controllable semiconductor means when said first and second pairs of switch means contacts are both closed and for removing said triggering signal a predetermined interval after either of said pairs of switch means contacts opens, whereby said controllable semiconductor means interrrupt current in said load circuits at current zero and said movable contacts and said switch means contacts never interrupt current.
Claim 21
Dependent Claim
192 words
In a voltage regulator, the combination of a tap changer switch having a plurality of stationary contacts and first and second movable contacts adapted to sequentially engage said stationary contacts in both bridging and nonbridging positions and to alternately move between stationary contacts, switch means having first and second pairs of normally closed contacts associated with and connected in series with said first and second movable contacts respectively forming first and second load circuits and having means to open each of said first and second pair of contacts before its associated movable contact disengages from a stationary contact and to reclose it after said movable contact engages a succeeding stationary contact, controllable semiconductor means connected between said first and second load circuits, and means for applying a triggering signal to said controllable semiconductor means when said first and second pairs of switch means contacts are both closed and for removing said triggering signal a predetermined interval after either of said pairs of switch means contacts opens, whereby said controllable semiconductor means interrrupt current in said load circuits at current zero and said movable contacts and said switch means contacts never interrupt current.
Claim 22
Dependent Claim
112 words
In a voltage regulator in accordance with claim 19 wherein said means for applying a triggering signal includes means coupled to at least one of said load circuits for deriving said triggering signal when current is flowing in said one load circuit, means including a capacitor in series with a resistor connected to be charged from said signal deriving means and to supply said triggering signal to said semiconductor means after deenergization of said signal deriving means, and means responsive to the opening of either of said pairs of switch means contacts for cutting off said triggering signal to said semiconductor means when the charge on said capacitor decays to predetermined magnitude.
Claim 23
Dependent Claim
38 words
In a voltage regulator in accordance with claim 20 wherein said signal deriving means includes transformer means and rectifier means between a secondary winding of said transformer means and the input triggering circuit to said controllable semiconductor means.
Claim 24
Dependent Claim
69 words
In a voltage regulator in accordance with claim 21 wherein said means for applying a triggering signal also includes shunt voltage regulator means between said rectifier means and said input triggering circuit and having a control element controllable semiconductor device in shunt to said input triggering circuit and wherein said means for cutting off said triggering signal biases said semiconductor device into saturation to cut off said triggering signal.
Claim 25
Dependent Claim
59 words
In the combination of claim 19 wherein said first and second pairs of switch means contacts are both connected to a load terminal and including a reactor having first and second windings connected in said first and second load circuits respectively between said first and second movable contacts and the associated first and second pairs of switch means contacts.
Claim 26
Dependent Claim
33 words
In the voltage regulator of claim 19 wherein said means for applying a triggering signal includes first and second current transformers having primary windings connected in said first and second load circuits respectively.
Claim 27
Dependent Claim
90 words
In the voltage regulator of claim 24 wherein said controllable semiconductor means comprises a pair of oppositely poled thyristors and said means for applying a triggering signal includes rectifier means between a secondary winding of at least one of said current transformers, and the cathode-gate circuits of said thyristors and means including a capacitor in series with a resistor connected to be charged by said rectifier means for supplying gating signals to said cathode-gate circuits of said thyristors for said predetermined interval after deenergization of either of said current transformers.
Claim 28
Dependent Claim
57 words
In the voltage regulator of claim 25 wherein said rectifier means includes a plurality of bridge rectifiers and said means for supplying gating signals also includes a shunt voltage regulator between the cathode-gate circuit of each thyristor and one of said bridge rectifiers and having a control element controllable semiconductor device in shunt to said cathode-gate circuit.
Claim 29
Dependent Claim
80 words
In the voltage regulator of claim 26 wherein first and second of said bridge rectifiers are energized from secondary windings of said first and second current transformers respectively and said means for supplying gating signals also includes OR circuit means for biasing said semiconductor devices in the active region when said first and second bridge rectifiers are energized and for biasing them in saturation after said predetermined time delay when either said first or said second bridge rectifier is deenergized.
Claim 30
Dependent Claim
60 words
In the voltage regulator of claim 27 wherein said means for biasing said semiconductor devices includes, for each said thyristor, first and second holding transistors and OR circuit means for biasing the semiconductor device associated therewith in the active region when both said holding transistors are conducting and for biasing it into saturation when either holding transistor is cut off.
Claim 31
Dependent Claim
76 words
In the voltage regulator of claim 28 wherein said means for biasing said semiconductor devices includes, for each said thyristor, first and second RC means including a timing capacitor in series with a resistor energized from said first and second bridge rectifiers respectively for forward biasing said first-and second-holding transistors respectively and for maintaining said forward bias after the corresponding bridge rectifier is deenergized until the voltage on the timing capacitor decays to a predetermined magnitude.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-11-01 | 1975-05-03 | 1975-11-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-11-01 | 1979-05-03 | 1979-11-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-11-01 | 1983-05-03 | 1983-11-02 | $7700.00 | Window Closed / Lapsed |