US3235694A - High voltage double break air switch with damping resistors - Google Patents

Description

Feb. 15, 1966 K. A. THALLNER HIGH VOLTAGE DOUBLE BREAK AIR SWITCH WITH DAMPING RESISTORS Filed Nov. 13, 1962 INVENTOR. Afl/QL 14. THAAL/V' United States Patent 3,235,694 HIGH VOLTAGE DOUBLE BREAK AIR SWHTCH WITH DAMPING RESISTQRS Karl A. Thallner, Geneva, Switzerland, assignor to l-T E Circuit Breaker Company, Philadelphia, ?a., a corporation of Pennsylvania Filed Nov. 13, 1962, Ser. No. 237,263 3 Claims. (Cl. 200-146) My invention relates to a novel double break switch which is provided with damping resistor means in parallel with each break for damping the charging current of sub-station buses or short transmission lines.

The introduction of resistors in parallel with the contacts of a single air break switch is well known to the art where the resistors are normally used to reduce current flow during load current interruption. Moreover, resistors are known for use with single air break switches vfor eliminating or attenuating transient phenomena which occur when switching charging currents of unloaded lines.

The principle of the present invention is to provide novel resistor means for each break of a double break air switch to attenuate those phenomena which occur when switching charging currents where highly unusual results occur, as contrasted to the application of resistor means to the single break type of switch.

When a high voltage air switch operates on the charging current of sub-station buses or short transmission lines, it is frequently found that this will cause lightning arrester operation, flash-overs of the main gap, or unsuccessful interruption of the relatively small current by the switch.

These phenomena create two major problems:

First, the re-ignitions and restrikes generate surges on the line which cause wave propagation and reflection operation which can easily mount to overvoltage values which cause the lightning arrester operation or flash-over. Second, this wave propagation appears across the switch gap and can, therefore, complicate the process of successful interruption. Moreover, these surges carry a considerable amount of energy which further complicates interruption.

These problems have been recognized, and solutions have been attempted in a single break switch wherein a resistor of a predetermined value is connected in series with the switch contacts where the resistor can be formed of a plurality of series connected elements with respective arcing electrodes. As the movable contact arm of the single break air switch moves to a disengaged position, the resistor sections are introduced step-by-step as by having the main blade of the air break switch pass the arcing electrodes of each resist-or section in sequence.

The total resistance required, and the number of resistor sections needed is normally of such value that the overall height of the resistor stack becomes appreciable. Because of this, the remaining gap distance in which final interruption takes place is greatly reduced.

It has been for this reason that the application of resistors for controlling charging currents in an air break switch has not been appreciably successful in commercial use.

The principle of the present invention lies in the recognition that a fixed amount of resistance or total height of resistor stack can be divided in two, one for each break when applied to a double break air switch. The electrodes of each resistor section at the respective breaks of the switch may then be simultaneously operated upon by electrodes extending from the movable contact arm to insert the resistor sections into the circuit in the usual manner. Alternatively, quick break contact means between the resistor and the movable switch contact may be employed.

With this novel construction, an optimum resistor value which is of the order of 2 to 4 times the surge impedance of the open end bus or transmission line which would typically range from 1,000 to 2,000 ohms can be distributed at the two breaks of the switch without causing an excessively high resistor stack, whereby the concept of modification of the phenomenon associated with interruption of charging current can now be successfully applied to air break switches.

Moreover, and because the resistors are now distributed between two breaks of the double break air switch, the commutation and final interruption takes place in two breaks so that the associated arcing will be considerably less than on a single break switch, and commutation can be more easily controlled. This is of considerable value when switching under severe wind conditions. Moreover, and because of the relatively small size of each of the resistor stacks, they can be adapted to standard double break switches, whereas in the case of the single break switch, the excessive length of the resistor stack requires special modification of the switch for the switch to mount the resistors.

Accordingly, a primary object of this invention is to provide resistor means for controlling the phenomena caused by interruption of charging currents by a high voltage air break switch.

Another object of this invention is to provide a relatively small height resistor for air break switches for controlling charging currents.

Another object of this invention is to provide a novel charging current control resistor for high voltage air break switches which will not interfere with the gap distance of the switch.

A further object of this invention is to provide a high voltage double break air switch with resistor sections at each break.

A further object of this invention is to provide resistors in parallel with each break of a double break air switch which utilize quick break contacts for final interruption at high opening speed.

A further object of this invention is to provide a total resistance in parallel with the contacts of a double break air switch which is 2 to 4 times the surge impedance of the open end bus or transmission line associated with the switch, although the length of the resistors is relatively small since they are divided between the two breaks.

These and other objects of my novel invention will become apparent from the following description when taken in connection with the drawings, in which:

FIGURE 1 shows a perspective View of a high voltage double break air switch which is provided with resistor sections at either end of the switch for controlling charging current during interruption.

FIGURE 2 shows a second embodiment of the invention wherein the resistors which cooperate with each of the breaks of the double break switch are provided with a quick break interrupter means.

Referring first to FIGURE 1, I have illustrated therein a single pole unit of a high voltage double break air switch which is carried on a main support base 10 which carries a first insulator stack 11, a second insulator stack 12 and a rotatable insulator stack 13. The insulator stack 11 carries a stationary contact jaw 14 which has a terminal pad 15 to which an electrical terminal may be connected.

In a similar manner, the insulator stack 12 has a'stationary contact jaw 16 which has a terminal pad 17 to which the second circuit terminal may be attached. The rotatable stack 13 then carries the main switch blade 18 which is terminated in contacts 19 and 20 at its respective ends.

Contacts 19 and 20 are engageable with stationary contacts 14 and 16 respectively in the usual and well known manner.

In accordance with the invention, a first resistor stack formed of resistor sections 21 and 22 are mounted on contact 14, and a second resistor stack formed of resistor sections 23 and 24 are mounted on stationary contact 16. Although the drawings show two sections of resistors (21 and 22 or 23 and 24), it is apparent that the invention could also be carried out by providing a single resistor at each end of switch; namely, resistor 21 on one end and resistor 23 at the other end of switch. With this arrangement single electrodes 25 and 27 would then be used.

The resistors 21 and 22 are electrically connected in series as are resistors 23 and 24. The lower end of resistor 21 is electrically connected to contact 14, while the lower end of resistor 23 is electrically connected to contact 16.

The junction between resistors 21 and 22 is then provided with an extending electrode 25, while the top of resistor 22 is provided with an extending electrode 26 which extends further outwardly than does extension 25. In a similar manner, the stack which includes resistors 23 and 24 has extending electrodes 27 and 28 respectively.

The electrodes 25 through 28 are commutation electrodes and cooperate with extending commutation horns 29 and 30 respectively which extend from the opposite ends of switch blade 18.

When switch blade 18 is in its closed position, it will be apparent that the resistor sections are short circuited. When, however, the blade 18 is moved toward its disengaged position by rotation of stack 13, the resistors 21 and 23 are initially connected in parallel with the main contacts at either end of the switch which have opened. When the switch blade 18 reaches a predetermined open position, the blade is disconnected from horns 25 and 27, and is connected to commutation electrodes 26 and 28 through the commutation horns 29 and 30 respectively. This corresponds to the commutation from the relatively low resistance of stacks 21 and 23 in parallel with the contacts to the insertion of the full resistance of stacks 21-22 .and 23-24 in parallel with the main contacts. Continued movement of blade 18 will ultimately result in complete disengagement of commutation electrodes 26 and 28 and horns 29 and 30 with the complete interruption :Of the circuit.

It will be noted that the resistor sections 21 through 24 have a certain required height. A very particular resistance, however, will be required for a particular system so that if the switch were a single break switch, it would still require the four resistor sections. These four resistor sections, however, when stacked on top of one another, create a relatively high stack as compared to only two where the height of the stack of four resistor sections would limit their application and could decrease the open gap of the switch. Therefore, there has been reluctance in the past to not utilize such resistor means.

In accordance with the present invention, however, :and in recognizing that the resistor sections can be distributed between the two breaks of a double break switch, 'I now am able to practically utilize the most desired resistor value for control of charging currents in an air break switch.

In a particular embodiment of the invention, it is desirable that the total resistance value be of the order of 2 to 4 times the surge impedance of an open end bus or transmission line which could, for example, be from 1,000 to 2,000 ohms in atypical system.

In a typical embodiment of the invention, as shown in FIGURE '1, the switch utilized could be of the type TTT manuiactured by the I-T-E Circuit Breaker Company and shown in their catalog sec. 1345 at page 6 thereof, dated J 2 1954.

The resistance sections utilized in such a switch for a particular application would include resistors having a total value of 2,000 ohms and formed by 4 units (resistor sections 21 through 24) which each have a height of 20 inches.

A second embodiment of the invention is shown in FIGURE 2 wherein numerals similar to FIGURE 1 identify similar components. FIGURE 2 differs from FIGURE 1 in that instead of commutating between the resistor sections, the commutating horns are replaced by quick break flexible conductors 40 and 41 which cooperate with extending electrodes 42 and 43 respectively at the top of resistors 22 and 24 respectively.

It will be further noted that the ends of blade 18 are provided with shock absorbers and guides 44 and 45 respectively for the quick break contacts 40 and 41 respectively.

The high speed travel that is obtained by the quick break horns 40 and 41 in FIGURE 2 operates to improve the interrupting ability of the air break switch so that it can interrupt charging current more efiectively.

Although I have described preferred embodiments of my novel invention, many variations and modifications will now be apparent to those skilled in the art, and I prefer, therefore, to be limited not by the specific disclosure herein, but only by the appended claims.

I claim:

1. In combination; a high voltage double break air switch and a first and second damping resistor means; said double break air switch comprising a movable blade and a first and second stationary contact positioned to be simultaneously engaged and disengaged by respective ends of said movable blade responsive to rotation of said blade; said first resistor means having a first terminal permanently connected to said first stationary contact and being mounted above said first stationary contact; said second resistor means having a first terminal permanently connected to said second stationary contact and being mounted above said second stationary contact; said first and second resistor means having second terminals; said second terminals of said first and second resistor means having first electrode means extending in a plane which is parallel to the plane of motion of said movable blade; said first electrode means being electrically connected to said respective ends of said movable blade when said respective ends of said movable blade engage said first and second stationary contacts; said first electrode means disengaging said respective ends of said movable blade after said movable blade is rotated by a predetermined amount toward a disengaged position; said respective ends of said rotatable blade having commutating horns connected thereto; said commutating horns extending from said respective ends of said rotatable blade to said first electrode means of said first and second resistor means respectively when said blade is in its said engaged position; said first and second resistor means including respective first and second resistor sections formed in a stack; the junction between said first and second resistor sections of said first and second resistor means having respective second electrode means extending in a plane which is parallel to the plane of motion of said movable blade and parallel to said first electrode means; said second electrode means being aligned with said first electrode means and being shorter than said first electrode means; said second electrode means engaging respective ends of said rotatable blade and dis engaging said rotatable blade prior to disengagement of said blade and said first electrode means.

2. The apparatus of claim 1 wherein said commutating horns include a portion extending transversely to the plane of motion of said blade, said portion engaging said first and second electrode means when said blade engages said first and second stationary contacts; said blade engaging said first electrode means only when said blade is rotated by a first predetermined amount; and

said blade disengaging said first electrode means, when said blade is rotated by a second predetermined amount.

3. In combination; a high voltage double break air switch and a first and second damping resistor means; said double break air switch comprising a movable blade and a vfirst and second stationary contact positioned to be simultaneously engaged and disengaged by respective ends of said movable blade responsive to rotation of said blade; said first resistor means having a first terminal permanently connected to said first stationary contact and being mounted above said first stationary contact; said second resistor means having a first terminal permanently connected to said second stationary contact and being mounted above said second stationary contact; said first and second resistor means having second terminals; said second terminals of said first and second resistor means having first electrode means extending in a plane which is parallel to the plane of motion of said movable blade; said first electrode means being electrically connected to said respective ends of said movable blade during an initial period of rotation of said movable blade; said first electrode means disengaging said respective ends of said movable blade after said movable blade is rotated by a predetermined amount toward a disengaged position; said respective ends of said rotatable blade having commutating horns connected thereto; said commutating horns including a portion extending transversely to the plane of motion of said blade, said portion engaging said first electrode means during an initial period of rotation of said movable blade; at least one of said first and second resistor means having a third resistor means mounted thereon, said third resistor means having a first terminal connected to said one of said first and second resistor means, and a second terminal, said second terminal having second electrode means extending in a plane which is parallel to the plane of motion of said blade; said portion of said commutating horns engaging said second electrode means of said third resistor means during an initial period of rotation of said movable blade.

References Cited by the Examiner UNITED STATES PATENTS 1,563,833 12/1925 Christensen 200-144 FOREIGN PATENTS 807,551 1/1959 Great Britain.

KATHLEEN H. CLAFFY, Primary Examiner. ROBERT K. SCHAEFER, Examiner.

Claims (1)

1. IN COMBINATION; A HIGH VOLTAGE DOUBLE BREAK AIR SWITCH AND A FIRST AND SECOND DAMPING RESITOR MEANS; SAID DOUBLE BREAK AIR SWITCH COMPRISING A MOVABLE BLADE AND A FIRST AND SECOND STATIONARY CONTACT POSITIONED TO BE SIMULTANEOUSLY ENGAGED AND DISENGAGED BY RESPECTIVE ENDS OF SAID MOVABLE BLADE RESPONSIVE TO ROTATION OF SAID BLADE; SAID FIRST RESISTOR MEANS HAVING A FIRST TERMINAL PERMANENTLY CONNECTED TO SAID FIRST STATIONARY CONTACT AND BEING MOUNTED ABOVE SAID FIRST STATIONARY CONTACT; SAID SECODN RESISTOR MEANS HAVING A FIRST TERMINAL PERMANENTLY CONNECTED TO SAID SECOND STATIONARY CONTACT AND BEING MOUNTED ABOVE SAID SECOND STATIONARY CONTACT; SAID FIRST AND SECOND RESISTOR MEANS HASVING SECOND TERMINALS; SAID SECOND TERMINALS OF SAID FIRST AND SECOND RESISTOR MEANS HAVING FIRST ELECTRODE MEANS EXTENDING IN A PLANE WHICH IS PARALLEL TO THE PLANE OF MOTION OF SAID MOVABLE BLADE; SAID FIRST ELECTRODE MEANS BEING ELECTRICALLY CONNECTED TO SAID RESPECTIVE ENDS OF SAID MOVABLE BLADE WHEN SAID RESPECTIVE ENDS OF SAID MOVABLE BLAE ENGAGE SAID FIRST AND SECOND STATIONARY CONTACTS; SAID FIRST ELECTRODE MEANS DISENGAGING SAID RESPECTIVE ENDS OF SAID MOVABLE BLADE AFTER SAID MOVABLE BLADE IS ROTATED BY A

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