US3126465A - Three-phase a - Google Patents

Three-phase a Download PDF

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Publication number
US3126465A
US3126465A US3126465DA US3126465A US 3126465 A US3126465 A US 3126465A US 3126465D A US3126465D A US 3126465DA US 3126465 A US3126465 A US 3126465A
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United States
Prior art keywords
arc
loop
loops
control device
gas outlet
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Expired - Lifetime
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English (en)
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H33/00—High-tension or heavy-current switches with arc-extinguishing or arc-preventing means
    • H01H33/70—Switches with separate means for directing, obtaining, or increasing flow of arc-extinguishing fluid
    • H01H33/72—Switches with separate means for directing, obtaining, or increasing flow of arc-extinguishing fluid having stationary parts for directing the flow of arc-extinguishing fluid, e.g. arc-extinguishing chamber
    • H01H33/75—Liquid-break switches, e.g. oil-break

Definitions

  • the invention relates to a three-phase A.C. power circuit-breaker, in which in three parallel planes lie three current loops with substantially parallel legs and each of these loops is provided with one or two arc-control devices-each incorporated in one of the parallel legswith lateral gas outlets, each of said arc-control devices containing a stationary contact and cooperating with a longitudinally movable switching member.
  • Various constructions of such circuit-breakers are known. A construction with two arc-control devices for each loop is described in Schakelingen, No. 33, March 1942, p. 474.
  • the invention has arisen from experiments with circuitbreakers of the type mentioned, with two arc-control devices for each current loop, from which it appeared that upon interruption of the current noproper arc positioning is attained, i.e., that when an arc is drawn in the arc-control devices and when gas under pressure consequently develops in said arc-control devices, the arc is unsteady and does not take up the proper position in front of the gas outlet. This phenomenon limits the circuit-breaking capacity of the circuit-breaker.
  • the invention meets this difiiculty to a considerable degree and moreover opens various favourable new possibilities.
  • each arc-control device in the central loop the gas outlet of each arc-control device lies in the plane through the two legs of this loop; that in each of the two outer loops the gas outlet of each arc-control device diverges relative to the gas outlet of the corresponding arc-control device of the central loop to a value a, determined by the formula (2) Ct C20 b in which a has a value of about 25 n is about 2.8, a is the distance between the two legs of each of the loops, and b is the distance between the planes of adjacent loops; and that the ratio a/b is between about 0.75 and about 0.45.
  • FIGURE 1 is a view in section of 6 conductors which define the current loops of the three phases.
  • FIGURES 2 through 4 show one embodiment of the invention.
  • FIGURE 2 is a vertical section
  • FIGURE 3 is a horizontal section along the line III-III of FIGURE Patented Mar. 24, 1964 2
  • FIGURE 4 is a diagrammatic plan on a smaller scale of the six arc-control devices.
  • the invention is based, among other things, on the realization that the ratio of the distance a between the two legs of each of the loops to the distance b between the planes of adjacent loops, i.e. the ratio a/ b, is a quantity which in several respects is decisive for the properties of the circuit-breaker.
  • FIGURE 1 a diagrammatic crosssection is given of the six conductors which form the legs of the current loops of the three phases.
  • On each of the legs forces are exerted by the currents in the other legs. It has been found that the greatest forces occur during the switching of highly asymmetric currents such as may occur for low values of cos (p, a power factor.
  • Formula II is of the same kind as Formula I. This means that as the ratio a/ b is reduced to distinctly below the value 1, not only the angle a but also the range ,8 of the direction of the resultant becomes more than proportionately smaller, a fact which is actually bound to promote an optimum arc positioning under any circumstances.
  • this angular width 5 may be chosen at least equal to u, and for the central phase at least equal to 'y. In this way it is ensured that during the switching the arc does not come into contact with the edges of the gas outlet, or at least as little as possible, a feature which greatly prolongs the life of the arc-control devices.
  • the dimensions of the outlets are partly also conditioned by the requirement of obtaining the gas pressure and velocity necessary for the arc extinction. From this point of view, too, a reduction of the ratio 11/17 is favourable. It results in a more than proportionate reduction of the required minimum angular width of the gas outlet and thus provides for ample play for the adaptation of the gas outlet openings to the required gas pressure.
  • the invention covers a range of the ratio a/b extending from about 0.75 to about 0.45.
  • this ratio is distinctly greater than 0.75, and if it is, for instance, nearly 1 or more than 1, which is the case with the above mentioned known circuit-breaker of the Schakelingen, No. 33, March 1942, publication with two arc-control devices for each loop, then-as has now been foundthe value of ,8 determined by Formula II (and thus certainly that of *y as well) is already so great that it is no longer possible at all to develop in the arc-control devices a gas pressure and velocity suflicient for the extinction of the arc. 'In that case therefore it is senseless to follow the said formula.
  • the section of FIGURE 2 lies in the plane of one of the three phases.
  • the two other phases lie behind the plane of the drawing.
  • the current loops of three phases are arranged in parallel planes in a vessel 1 filled with an insulating medium,
  • Each loop comprises a contact bridge 2 with two parallel contact rods 3, which cooperate with two stationary contacts 4.
  • Each of these stationary contacts 4 is located in an arc-control device 5, made, e.g., of nylon, containing insulating bodies 15 and 16, with a lateral gas outlet 6. Both the stationary contact 4 and the arccontrol device 5 are supported by a lead-in insulator 7 passing through the cover 8 of the vessel 1.
  • the contact bridges 2 of the three loops are coupled with and operated by a joint member 9, which extends perpendicular to the plane of the drawing in the vessel 1 and in a way not shown can be moved down with a view to opening the circuit-breaker and up with a view to closing the circuit-breaker.
  • FIGURE 2 shows the circuit-breaker at a moment it is in course of being opened. Between each contact rod 3 and each stationary contact 4 an arc 10 is then drawn. In the arc-control device 5 gas under high pressure develops in the known way, which gas escapes through the gas outlet 6.
  • the two arc-control devices 5 in FIGURE 2 are placed so close together that they are in contact with each other, in order to obtain a small ratio a/b.
  • the distances a and b are given; their ratio is less than 0.75.
  • the two arc-control devices of the central loop have gas outlets which are directed away from each other in the plane through the two legs of this loop.
  • the two arc-control devices of each of the two outer loops have gas outlets each of which diverges over the angle on relative to the gas outlet of the corresponding arc-control device of the central loop.
  • the actual angular width 6 of the gas outlets is at least p for the two outer phases and at least 7 for the central phase (which cannot be seen).
  • the divergence a is about and the angle 5 is about 10.
  • the invention of course also applies to a double arccontrol device, in which the two individual devices are combined to one single constructional unit.
  • a three-phase A.C. electric circuit-breaker in which in three parallel planes lie three current loops with substantially parallel legs and each of these loops is provided with at least one arc-control device--each incorporated in one of the parallel legswith lateral gas outlets, each of said arccontrol devices containing a stationary contact and cooperating with a longitudinally movable switching member, characterized in that in the central loop and gas outlet of each arc-control device lies in the plane through the two legs of said loop; that in each of the two outer loops the gas outlet of each arccontrol device diverges relative to the gas outlet of the corresponding arc-control device of the central loop to a value a, determined by the formula a D e in which 04 has a value of 25, n is 2.8, a is the distance between the two legs of each of the loops, and b is the distance between the planes of adjacent loops; and that the ratio a/ b is in the range between 0.75 and 0.45.
  • each of the gas outlets of the two outer loops viewed from the centre line of the arc-control device in question, has an angular range of at least ⁇ 3, determined by the formula in which d has a value of 40.

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  • Arc-Extinguishing Devices That Are Switches (AREA)
  • Circuit Breakers (AREA)
US3126465D 1959-06-30 Three-phase a Expired - Lifetime US3126465A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL240752A NL106329C (en, 2012) 1959-06-30 1959-06-30

Publications (1)

Publication Number Publication Date
US3126465A true US3126465A (en) 1964-03-24

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ID=19751800

Family Applications (1)

Application Number Title Priority Date Filing Date
US3126465D Expired - Lifetime US3126465A (en) 1959-06-30 Three-phase a

Country Status (5)

Country Link
US (1) US3126465A (en, 2012)
BE (1) BE590211A (en, 2012)
FR (1) FR1261130A (en, 2012)
GB (1) GB926363A (en, 2012)
NL (1) NL106329C (en, 2012)

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
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Also Published As

Publication number Publication date
NL106329C (en, 2012)
GB926363A (en) 1963-05-15
FR1261130A (fr) 1961-05-12
BE590211A (nl) 1960-08-16

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