JP6340991B2 - Closed switchboard - Google Patents

Description

  The present invention relates to a closed type switchboard for power receiving boards, busbar boards, etc., in which main circuit conductors corresponding to each phase of a power supply are arranged in parallel in the board, and more particularly, based on a short circuit accident between main circuits. The arc extension of the board casing was restricted and the arc resistance of the board casing was improved so that the arc that propagated between the conductors of the circuit conductor and propagated to the end of the conductor did not touch the wall of the board casing. It relates to the wiring structure in the panel.

  In this type of closed type switchboard, when a short circuit accident occurs between the main circuit conductors (main busbars) corresponding to each phase of the power supply installed in the panel, a flash arc occurs between the lines of the main circuit conductor. Occur. In this case, if the main circuit conductor is a bare bar conductor (copper, aluminum bar), the arc is powered by the Lorentz force acting between the magnetic field of the conductor current flowing from the power source side to the arc generation point and the arc current. Propagation is driven in the direction from the side toward the load side.

  Next, with respect to the conventional wiring structure of the main circuit conductor laid in the panel of the closed type distribution board, and the behavior of the arc ignited between the lines of the main circuit conductor based on the phase short circuit accident of the main circuit, FIG. 5 will be described. In the figure, 1 is a panel housing of a closed type switchboard (busbar panel), 1a is a wall surface of the panel housing 1, 2 is arranged in parallel in the vertical direction and laid inside the panel housing 1, and a power supply side cable (not shown) The main circuit conductor 2a is composed of a bare bar conductor (copper bar) corresponding to each of the R, S, and T phases connected to), and is directed from the middle of the main circuit conductor 2 of each phase toward the load side equipment of the lower system Branch circuit conductors 2b branched in a substantially right-angle direction are conductor terminal portions opposite to the power supply side of the main circuit conductor 2. The tip of the conductor terminal portion 2b is opposed to the board surface 1a of the board casing 1 with an air insulation distance L (for example, conforming to the standard of “Japan Switchboard Industry Association”).

  With the above wiring structure, if an unexpected inter-phase short-circuit accident occurs in the main circuit conductor 2 in the panel during power reception by the switchboard, and an arc arc occurs between the lines of the main circuit conductor 2 based on this short-circuit accident, this arc Behaves as follows by receiving the Lorentz force F acting between the magnetic field of the current flowing in the main circuit conductor 2 and the arc current from the power source side toward the arc firing point.

  That is, the arc arc ignited between the lines of the main circuit conductor 2 is an arc spot as a free arc and an arc column extending between the arc spots as shown in FIG. Propagated at high speed. The arc propagated to the branch position of the branch circuit conductor 2a in the arc propagation process passes through the branch point of the branch circuit conductor 2a by the driving of the Lorentz force F acting in the longitudinal direction of the main circuit conductor 2 and proceeds straight as it is. The arc spot stagnates at this position when it reaches the tip of the conductor terminal portion 2b of the main circuit conductor.

  In this arc propagation process, when the arc propagates from the middle of the main circuit conductor to the branch circuit conductor branched to the load side equipment, the load side equipment connected to the branch circuit conductor and the periphery thereof are arranged. The measurement and control equipment may be burned and damaged by exposure to the arc. However, if the main circuit conductor 2 is provided with the conductor termination portion 2b as described above, the arc crosses the branch point of the branch circuit conductor 2a. Since it passes through and propagates straight to the conductor terminal portion 2b, the load side device connected to the branch circuit conductor 2a is not exposed to the arc.

  On the other hand, in addition to the above-mentioned wiring structure in the panel, as a measure for preventing the arc generated between the lines of the main circuit conductor from propagating to the load side equipment, a key point in the middle of the main circuit conductor laid in the panel In addition, an arc horn-shaped auxiliary conductor that guides the arc to the side away from the main circuit conductor is provided, and when a short-circuit arc occurs between the lines of the main circuit conductor, the arc is removed from the main circuit conductor. There is also known a wiring structure of a closed type switchboard in which an arc is stagnated at the end of the auxiliary conductor to prevent arc propagation to a load side device after being guided to the auxiliary conductor (see, for example, Patent Document 1). ).

JP-A-6-38315

  By the way, the conventional in-panel wiring structure of the closed type switchboard shown in FIGS. 3 and 4 has the following problems. That is, the arc arc generated between the lines of the main circuit conductor 2 due to the short circuit between the phases of the main circuit propagates to the conductor terminal portion 2b of the main circuit conductor 2 and stays at this position, and the circuit breaker on the power source side When this arc continues until it operates and disconnects the circuit of the main circuit, the arc column extended between the arc spots receives a coulomb force F, curves forward, and further extends. .

  In this case, if the insulation distance L set in advance between the conductor terminal end 2b of the main circuit conductor 2 and the panel surface 1a of the panel housing is not sufficient, the tip of the conductor terminal end 2b as shown in FIG. The arc column of the arc arc stagnated in the position extends to directly touch the panel surface 1a of the panel casing. For this reason, the wall surface 1a of the panel casing is exposed to a high-temperature arc and is damaged (burn-through), and there is a risk that a high-temperature, high-pressure arc flash will blow out to a secondary disaster.

  Therefore, in order to prevent an arc accident in which the arc that is ignited between the lines of the main circuit conductor 2 and propagates to the conductor end portion 2b directly touches the panel casing and damages the wall surface 1a, the main circuit conductor 2 It is necessary to set and secure a sufficient insulation distance L in consideration of the above-described arc extension between the conductor terminal portion 2b and the wall surface 1a of the panel housing.

  However, when the insulation distance L is increased, the outer size of the panel housing 1 becomes larger than necessary, and it becomes difficult to reduce the size of the panel. In addition, when the insulation distance L between the conductor terminal end 2b of the main circuit conductor 2 / the wall surface 1a of the housing is increased, the arc length that extends forward from the state where the arc stagnates in the conductor terminal end 2b of the main circuit conductor 2 Since the arc voltage increases, the arc energy released to the surroundings also increases, which causes a problem that the pressure inside the panel is rapidly increased and the risk of damage to the panel casing is further increased. It should be noted that such a problem of damage to the panel housing can also occur in the arc guiding auxiliary conductor disclosed in Patent Document 1.

  The present invention has been made in view of the above points, and the air insulation distance L set between the conductor terminal portion of the main circuit conductor laid in the board and the board surface of the board casing is increased more than necessary. None, the arc extension between the main circuit conductors due to a short circuit between the phases and the propagation of the arc propagated to the terminal end of the conductor is restricted to the minimum arc length so that the arc does not directly touch the enclosure. It is an object of the present invention to provide a closed type switchboard with an improved wiring structure in the board for the main circuit conductor so as to improve the arc resistance of the board and to reduce the size of the board housing.

In order to achieve the above object, according to the present invention, in a closed type distribution board in which main circuit conductors that become bare bar conductors corresponding to respective phases of a power supply are laid in parallel inside the panel casing, Between the main circuit conductor and the wall surface of the board casing opposite to the power supply side, the floating electrode is ungrounded with a gap from the end face of the main circuit conductor conductor and the board casing. It is assumed that they are interposed (Claim 1), and the floating electrode can be specifically configured in the following manner.
(1) The floating electrode has an opposing surface area that collectively surrounds the conductor terminal end face of the main circuit conductor of each phase, and the outer peripheral surface area is concave toward the conductor terminal end of the main circuit conductor. (Claim 2).
(2) An arcuate curved surface is formed on the outer peripheral edge of the floating electrode.
(3) The spatial distance between the surface of the floating electrode and the end surface of the conductor terminal portion of the main circuit conductor is set to about ½ of the interphase insulation distance of the main circuit conductor.
(4) The floating electrode described in the preceding items (1) to (3) is insulatively supported on the wall surface of the panel housing via an insulator (claim 5).

According to the said structure, there can exist the following effect.
(1) When an arc ignited between the lines of the main circuit conductor is propagated to the end of the conductor of the main circuit due to the short circuit accident between the main circuits, the arc column becomes the main circuit conductor. The arc is stagnated and held at this position by commutation to a floating electrode interposed between the conductor terminal portion and the wall surface of the panel casing. As a result, the floating electrode serves as an arc barrier and the arc propagated to the conductor end of the main circuit conductor does not directly touch the wall surface of the board casing, thereby damaging the panel casing due to contact with the arc (burning).・ Through-through) can be safely protected.
(2) Further, the floating electrode has an opposing surface area that collectively encloses the end surface of the conductor terminal of each phase conductor, and the outer peripheral surface thereof has a concave shape toward the conductor terminal of the main circuit conductor. By forming an arcuate curved surface at the outer peripheral edge portion, the main circuit conductor that is the charging unit and the floating electrode that is in an electrically floating (non-grounded) state are formed. While avoiding local electric field concentration, it is possible to prevent the occurrence of unnecessary flashing between the main circuit conductor and the floating electrode during power reception by bringing the electric field between the two close to the equal electric field distribution.
(3) Furthermore, by setting the spatial distance between the surface of the floating electrode and the end surface of the conductor terminal of the main circuit conductor to about 1/2 of the interphase insulation distance of the main circuit conductor, the conductor terminal / floating The arc length of the arc commutated from the conductor end of the main circuit conductor to the floating electrode is restricted to the minimum length while ensuring the insulation strength between the electrodes to be equivalent to the interphase insulation strength of the main circuit conductor. It is possible to suppress the voltage to a low level, thereby suppressing an increase in arc energy released to the surroundings and reducing the risk of damage to the panel housing due to a rapid increase in the pressure in the panel.
(4) In addition, the floating electrode can be insulated and supported on the wall surface of the panel housing through the insulator, thereby preventing the phase short circuit of the main circuit from progressing to a ground fault.

  From these effects, compared with the conventional wiring structure of the closed type switchboard, the arc-proof performance of the panel casing can be improved and the closed type switchboard can be downsized.

FIG. 4 is a wiring structure diagram of a main circuit conductor laid in a panel according to an embodiment of the present invention, and shows a structure of a floating electrode that is disposed in the middle of the wall surface of the panel casing so as to face the conductor terminal portion of the main circuit conductor. FIG. FIG. 2 is an explanatory diagram showing the behavior of an arc generated when the main circuit conductor is short-circuited between phases, and (a) and (b) schematically show the behavior of the arc propagated to the conductor termination and the state of extension, respectively. They are a perspective sectional view and a side view sectional view. It is a model perspective view showing the conventional wiring structure of the main circuit conductor laid in the panel of a closed type switchboard. FIG. 4 is a schematic explanatory diagram showing the behavior and propagation path of a short-circuit arc between phases generated in the main circuit conductor of FIG. 3. FIG. 5 is a schematic diagram illustrating a state in which an arc propagated to the conductor terminal end portion of the main circuit conductor is further extended and is in contact with the wall surface of the board housing in FIG. 4.

  Hereinafter, an embodiment of a closed type switchboard according to the present invention will be described based on the examples shown in FIGS. In addition, in the figure of an Example, the same code | symbol is attached | subjected to the member corresponding to FIG. 3, FIG. 4, and the detailed description is abbreviate | omitted.

  That is, in the closed type switchboard shown in FIGS. 1 and 2, the conductor termination on the opposite side to the power supply side of the main circuit conductor 2 corresponding to the R, S, and T phases arranged in parallel in the vertical direction inside the panel housing. The main circuit conductor 2 and the floating electrode 3 facing each other with a gap from the wall surface 1a of the panel housing are interposed between the wall surface 1a of the panel housing and facing the tip of the part 2b. The electrode 3 is insulatively supported on the wall surface 1a of the panel casing which is grounded via the support insulator 4.

  Here, the floating electrode 3 is formed in an arc-resistant metal plate such as a tungsten alloy in the following shape. In other words, the floating electrode 3 has an elliptical opposing surface area that collectively surrounds the ends of the conductor termination portions 2b of the R, S, and T phases arranged in the vertical direction, and the outer peripheral surface area of the conductor termination portion 2b. It consists of a tray-like body having a concave curved surface toward the end face, and the spatial distance d2 between the surface of the floating electrode 3 and the end face of the main circuit conductor terminal portion 2b is the interphase insulation distance of the main circuit conductor 2. d1 is set to about 1/2 of that.

  The curvature of the concave curved surface formed in the outer peripheral surface area of the floating electrode 3 is set so that the radius of curvature R centered on the tip surface of the conductor terminal portion 2b is substantially the same as the spatial distance d2. An arcuate curved surface R is formed on the outer peripheral edge so as to alleviate electric field concentration with the main circuit conductor 2. Note that d3 shown in FIG. 2B is the air insulation distance between the wall surface 1a of the panel housing and the floating electrode 3 supported via the support insulator 4, and d4 is the conductor of the main circuit conductor 2. This is the gap distance between the end portion 2b and the wall surface 1a of the panel casing.

  Next, the function of the floating electrode 3 interposed between the conductor terminal portion 2b of the main circuit conductor 2 and the wall surface 1a of the panel housing, and the behavior of the short-circuit arc commutated to the floating electrode 3 are shown in FIG. This will be described with reference to (a) and (b). In the drawing, a state where a three-phase short circuit has occurred in the three-phase power supply circuit is shown.

  That is, when the arc arc ignited between the lines of the main circuit conductor 2 due to the short circuit between the main circuit phases propagates from the power source side to the conductor terminal portion 2b by the electromagnetic drive of the Lorentz force F and stops at this position, An arc column extending in an arch shape forward from the arc point (arc spot) is transferred to the floating electrode 3 opposed to the conductor terminal portion 2b with a gap therebetween, and the current I is floated from the main circuit conductor 2 as illustrated. 3 to commutate and flow. Further, in this commutation state, the arc arc is divided into the forward path side and the return path side of the current I, and the divided arc extends between the tip of the conductor terminal portion 2b and the plate surface of the floating electrode 3 and stays at this position. It will be retained.

  Therefore, the arc commutated from the conductor terminal portion 2b of the main circuit conductor 2 to the floating electrode 3 may wrap around the back surface side of the floating electrode 3 and contact the wall surface 1a of the board housing facing the back. Thus, it is possible to protect the panel casing by preventing the occurrence of an arc accident in which the wall surface 1a of the panel casing is damaged (burn-through) by direct contact with the arc.

  In this case, in the illustrated three-phase short-circuited state, the split arc generated between the S-phase main circuit conductor 2 and the floating electrode 3 extends substantially linearly, whereas R, The divided arc that is generated between the T-phase main circuit conductor 2 and the floating electrode 3 is directed toward the outer peripheral side of the floating electrode 3 so as to be separated from the S-phase arc due to the relationship between the current direction and the current magnetic field. Propagates in an arch shape. In this case, the spatial distance d2 between the conductor terminal portion 2b and the surface of the floating electrode 3 is set to about ½ of the interphase insulation distance d1 of the main circuit conductor 2 as described above. Since the outer peripheral side surface area is a concave curved surface having a radius of curvature R (R≈d2), the arc length La is divided by commutation from the conductor terminal portion 2b of each phase R, S, T to the floating electrode 3 as shown in the figure. Are approximately the same arc length in each phase. Further, the arc length obtained by summing the divided arcs extending toward the forward path and the return path of the arc current, and the arc voltage thereof are substantially the same as the arc generated between the lines of the main circuit conductor 2. In other words, even when the arc generated between the lines of the main circuit conductor 2 commutates to the floating electrode 3 and is divided to the forward and return paths, the effective arc length and arc voltage are the same between the lines of the main circuit conductor 2. Is limited to substantially the same value as that of the arc generated.

  In addition, since the distance d2 between the conductor terminal portion 2b of the main circuit conductor 2 and the floating electrode 3 is set to about ½ of the interphase insulation distance d1 of the main circuit conductor 2, the conductor of the main circuit conductor 2 The withstand voltage strength of the path from the terminal portion 2b through the floating electrode 3 can be maintained at the same withstand voltage strength as between the phases of the main circuit conductor 2, and the outer peripheral edge of the floating electrode 3 is chamfered into an R shape to localize electric field concentration. Since relaxation is performed, there is no possibility that a flashing will occur between the main circuit conductor 2 and the floating electrode in the normal power receiving state.

  In addition, since the floating electrode 3 is electrically supported in a floating state with respect to the wall surface 1a of the panel housing via the support insulator 4, the arc arc generated between the lines of the main circuit conductor 2 is floated. When commutating to the electrode 3, it is possible to prevent a ground fault from progressing.

  As is clear from the above description, according to the in-panel wiring structure of the illustrated embodiment, the arc that is ignited between the lines of the main circuit conductor 2 and propagates to the conductor terminal portion 2b based on the short circuit between the phases of the main circuit. There is no risk of the panel casing being damaged (burn-through) by directly touching the wall surface 1a of the panel casing, thereby improving the arc resistance performance of the panel casing.

  Therefore, as described in the conventional wiring structure (see FIG. 5), the generated arc is prevented from directly contacting the wall surface 1a of the panel housing between the conductor terminal portion 2b of the main circuit conductor 2 and the wall surface 1a. The insulation distance L to be set does not need to be expanded in advance beyond the standard specified distance in anticipation of the extension of the arc, and the distance between the conductor terminal portion 2b and the floating electrode 3 shown in FIG. It is possible to reduce the external size of the closed type switchboard by reducing d2 and the distance d4 between the conductor terminal portion 2b / the wall surface 1a of the panel housing including the insulation distance d3 between the floating electrode 3 / the wall surface 1a of the panel housing. Become.

  Further, the distance d2 between the conductor terminal portion 2b of the main circuit conductor 2 and the floating electrode 3 is set to about 1/2 of the interphase insulation distance d1 of the main circuit conductor 2, and the commutation to the floating electrode 3 occurs. By suppressing the arc length of the arc to the minimum length, the increase in arc voltage and the increase in arc energy released to the surroundings are suppressed, and the risk of damage to the panel casing due to a sudden rise in the panel pressure is reduced. Can be reduced.

1: Panel housing of closed type switchboard 1a: Wall surface 2: Main circuit conductor 2a: Branch circuit conductor 2b: Conductor termination 3: Floating electrode 4: Insulation support insulator arc: Arc

Claims (5)

In a closed type switchboard in which main circuit conductors that become bare bar conductors corresponding to each phase of the power supply are laid in parallel inside the panel housing,
A floating electrode is provided between the main circuit conductor of each phase and the wall surface of the board casing opposite to the power supply side with a gap between the end face of the conductor terminal of the main circuit conductor and the board casing. A closed type switchboard that is placed in an ungrounded state.   2. The closed type switchboard according to claim 1, wherein the floating electrode has an opposing surface region that collectively surrounds the end surface of the conductor terminal of the main circuit conductor of each phase, and the outer surface of the floating electrode has a conductor terminal of the main circuit conductor. A closed type switchboard characterized in that a concave curved surface is formed toward the part.   3. The closed type switchboard according to claim 1 or 2, wherein an arcuate curved surface is formed on the outer peripheral edge of the floating electrode. The closed type switchboard according to any one of claims 1 to 3, wherein a spatial distance between the surface of the floating electrode and an end surface of the conductor end portion of the main circuit conductor is set to about 1/2 of an interphase insulation distance of the main circuit conductor. Closed type switchboard characterized by that.   5. The closed type switchboard according to any one of claims 1 to 4, wherein the floating electrode is insulated and supported on the wall surface of the board casing through an insulator.