JPH0443953Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial field of application] This invention is designed to prevent damage to one part of the distribution line due to overload or short circuit.
The present invention relates to a short-circuit device for protecting an open phase, which prevents an open phase accident by blowing out the fuses of other phases when a fuse of a phase is blown.

[Conventional technology]

If a fuse in one phase of a three-phase distribution line blows out, load-side equipment, especially rotating equipment such as three-phase induction motors, will stop rotating, and in this stopped state, short-circuit current will flow from the other two phases. The flow causes equipment on the load side to burn out. In order to prevent damage to equipment on the load side due to such open-phase accidents,
A short-circuit device for protecting an open phase has been proposed, which instantly and automatically blows out fuses of other phases when a fuse of a phase blows out. One of them is a short-circuiting device for protecting against an open phase, which is disclosed in Japanese Utility Model Publication No. 13161/1983. This shorting device for protection against phase loss has a trigger fuse installed in parallel with the main fuse of each phase, and when the main fuse blows out due to overcurrent, the trigger fuse is activated, and the activation of the trigger fuse activates the shorting piece. This short-circuits all three phases at once.

In addition, as another short-circuit device for open phase protection, Jikosho
There is one shown in Publication No. 62-2889. This short circuit device for protecting an open phase detects an overcurrent, operates a relay, heats a bimetal piece by the operation of the relay, and short-circuits three phases by heating and deforming the bimetal piece.

[Problem that the invention attempts to solve]

However, according to the former short circuit device for protection against phase loss,
It is difficult to check whether the trigger fuse is working. In particular, if a link fuse with arc-extinguishing sand sealed in a ceramic case is used, it is possible to muffling noise during operation and prevent oxidation deterioration of the fuse, but it is difficult to confirm whether the fuse has blown out. Furthermore, since the triggering force of the trigger fuse cannot be made that large, some measures have been taken, such as using rotational force to operate the shorting piece. Therefore, the configuration becomes complicated.

Further, according to the latter short-circuiting device for protecting against an open phase, three-phase short-circuiting is performed by heating and deforming the bimetallic piece, so there are disadvantages in that the operating time varies and the operation is delayed due to a delay in thermal response.

[Means for solving problems]

The present invention has been developed in view of the above, and it is possible to easily check the trigger fuse for melting, to perform a three-phase short-circuit operation reliably with a small trigger force, and with a simple configuration, and to improve responsiveness. Provided is an excellent short-circuit device for open phase protection.

That is, the short-circuit device for protection against open phase of the present invention includes the following means.

(1) Trigger fuse This fuse detects the blowout of the main fuse installed in the distribution line, and is installed in each phase in parallel with the main fuse of each phase of the distribution line. This trigger fuse has a trigger wire that blows out based on the blowout of the corresponding main fuse to detect the blowout of the main fuse, and a trigger that protrudes when the trigger wire blows out. The protrusion of the trigger is effected by the force of a coiled spring or the like, and the trigger wire acts against this spring force to hold the trigger in place. The protruding trigger applies a propulsion force to the shorting piece, which will be described later. The trigger fuse has an operation indicator plug that projects simultaneously in a direction different from that of the trigger, and the projection of the operation indicator plug makes it possible to visually confirm the operation of the trigger fuse.

(2) Shorting switch This is a contact switch that shorts the three phases or other phases of the distribution line based on the detection of the main fuse blowing by the trigger fuse. Under normal conditions, the shorting piece is in an open state with the fixed contact of the distribution line.
When the trigger protrudes from the trigger fuse, it is actuated into contact with the stationary contacts of the distribution line, creating a short circuit.

[Effect]

With the above configuration, when the main fuse of one phase of the distribution line blows out, the trigger wire of the trigger fuse connected in parallel with the main fuse blows out, causing the trigger to protrude. The protruding trigger applies actuation force to the corresponding shorting piece, and the shorting piece forms a short circuit between the three phases or the other phases, and blows out the remaining main fuses. In this case, the shorting piece receives actuation force from the trigger and moves in the protruding direction of the trigger. At this time, when the shorting piece moves slightly, a magnetic attraction force acts between it and the fixed contact, thereby reliably closing the fixed contact. At the same time, an indicator plug protrudes from the opposite side of the trigger fuse to indicate activation of the trigger fuse. Therefore, since a link fuse can be used, a noise reduction effect can be expected, and oxidation deterioration of the fuse can be prevented. Since no bimetal pieces are used, high-speed response is achieved. Also,
Since the shorting piece is simply moved a minute distance in the protruding direction of the trigger, a large triggering force is not required and the configuration can be simplified.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail.

Fig. 1 shows a circuit diagram of a short circuit device installed on the load side, and shows a U-phase branched from the main line (not shown),
Load-side distribution lines 3U, 3V, and 3W are connected to the V-phase and W-phase branch lines 1U, 1V, and 1W via main fuses 2U, 2V, and 2W, respectively. The load-side distribution lines 3U, 3V, and 3W serve as output lines to load-side equipment such as rotating equipment. Each branch line 1U, 1V, 1W and load side distribution line 3
Trigger fuses 4U, 4V, 4W for U phase, V phase, and W phase are connected to each main fuse 2 for U, 3V, and 3W.
It is inserted in parallel with U, 2V, and 2W. Furthermore, shorting pieces 5U, 5V, and 5W corresponding to the respective trigger fuses 4U, 4V, and 4W are provided. Here, the U-phase shorting piece 5U forms a short circuit with the other two-phase load-side distribution lines 3V, 3W, and the V-phase shorting piece 5V forms a short-circuit with the other two-phase load-side distribution lines 3U, 3W. The W-phase shorting piece 5W connects the other two phase load-side distribution lines 3U and 3V so as to form a short circuit with the
and is provided to form a short circuit. Therefore, the shorting piece 5U is provided with the fixed contact 6V of the load side distribution line 3V and the fixed contact 7W of the load side distribution line 3W, and the shorting piece 5V is provided with the fixed contact 8U of the load side distribution line 3U. The fixed contact 7W of the load side distribution line 3W is provided correspondingly, and the shorting piece 5
W is provided with a fixed contact 8U of the load side distribution line 3U and a fixed contact 6V of the load side distribution line 3V in correspondence with each other. Each shorting piece 5U, 5V, 5W is normally held apart from the fixed contact, and is displaced into contact with the fixed contact by the operation of the corresponding trigger fuse 4U, 4V, 4W. The structure of these shorting pieces 5U, 5V, and 5W will be described later.

Figure 2 shows trigger fuses 4, 4U, 4V, 4W.
This figure shows a cross-sectional structure in which a trigger 42 and an operation indicator plug 43 are housed in a vertically long insulating cylinder 41. These trigger 42 and operation indicator plug 43 are provided at both ends of the insulating cylinder 41, and both are biased by coil springs 45, 46 so as to protrude from both ends of the insulating cylinder 41. In addition, the insulation tube 4
A trigger wire 44 that passes through a trigger 44 and an operation indicator plug 43 is inserted in the axial direction into the inside of the trigger wire 44 . Flange portions 44a are provided at both ends of the trigger wire 44,
44b is provided, each flange portion 44a, 44b
are engaged with the trigger 42 and the operation indicator plug 43, respectively, thereby holding the trigger 42 and the operation indicator plug 43 so that they do not protrude from the insulating cylinder 41.
On the other hand, when the trigger wire 44 is fused, the holding state is released, and the trigger 42 and the operation indicator plug 43 protrude from the insulating cylinder 41 by the spring force of the coil springs 45 and 46. As a result, the trigger 42 is activated by the corresponding shorting piece 5.
Press U, 5V, 5W to short-circuit the distribution line,
On the other hand, the operation indicator plug 43 is designed to be easily visible to the operator. Note that terminal fittings 4 electrically connected to the distribution line are provided at both ends of the insulating tube 41.
7,47 are provided. A lead metal fitting 48 is connected to the terminal metal fitting 47 on the trigger 42 side, and the lead metal fitting 48 and the trigger wire 44 are connected directly or via a spring 45. As a result, the trigger wire 4 connecting both terminal fittings 47, 47 to the distribution line
4 is connected in parallel with the main fuse of each phase.

The short circuit operation of this embodiment will be explained below.

The main fuse of one phase of the three-phase distribution line, for example, the U-phase main fuse 2U, may be damaged due to overcurrent, etc.
When the main fuse 2U is fused, the trigger wire 44 of the trigger fuse 4U connected in parallel with the main fuse 2U is fused. The trigger wire 44 is blown out by the trigger fuse 4.
Since U is in parallel with main fuse 2U, this is done immediately after main fuse 2U is blown.
By fusing the trigger wire 44, the trigger 42 and the operation indicator plug 43 protrude from the insulating tube 41.
Since the protruding trigger 42 presses the corresponding shorting piece 5U, the shorting piece 5U connects the fixed contact 6V of the load side distribution line 3V and the fixed contact 7W of the load side distribution line 3W.
in contact with the V-phase and W-phase load side distribution lines 3V,
Short-circuit 3W. As a result, these distribution lines 3
Main fuse 2V installed in V, 3W,
2W are simultaneously fused and the power supply to the load side equipment is cut off, so it is possible to prevent burnout due to an open phase in the load side equipment. These operations are performed in the same way even when the main fuses of the V phase and W phase other than the U phase are blown out. In this type of operation, the trigger fuse automatically operates immediately after the main fuse of one phase blows out, and based on this, the main fuses of other phases blow out, ensuring that the load-side equipment does not burn out due to an open phase. It can be prevented.

FIG. 3 is a sectional view showing the relationship between the shorting piece and the fixed contact, and FIGS. 4a and 4b are sectional views showing the operation thereof. The movable contacts 11 correspond to the short circuit piece 5U in FIG. 11, and two movable contacts 11 are provided so as to contact the fixed contacts 13, which correspond to the fixed contacts 6V and 7W in FIG. It is constructed to move. A trigger fuse 4 is disposed behind the movable contact 11, and when the trigger 42 protrudes, the movable contact 11 moves in the direction of the fixed contact 13. Also,
The movable contacts 11 are attached to shafts 24, each of which is inserted into a coil spring 25. As a result, the movable contact 11 is connected to the fixed contact 13.
It is energized in the direction away from the Further, both the movable contact 11 and the fixed contact 13 are provided on the surfaces of suction iron pieces 17 and 18 that exert suction force on each other. In such a structure, trigger fuse 4
In a normal state in which the trigger 42 does not protrude from the main fuse, that is, in a normal state in which the main fuse does not blow out, the movable contact 11 is held by the spring force of the coil spring 25 so as not to come into contact with the fixed contact 13, as shown in FIG. 4a. Therefore, even if an external force such as vibration is applied, the movable contact 11 will not come into contact with the fixed contact 13 inadvertently. Next, when the main fuse blows out and the trigger 42 of the trigger fuse 4 protrudes, the movable contact 11
moves in the direction of the fixed contact 13 against the spring force.
This movement causes the suction iron pieces 17, 18 to approach each other, so the suction force increases, and the suction iron pieces 17, 18
As shown in Fig. 4b, the movable contact 11
contacts the fixed contact 13. This short-circuits the distribution line, but since the movable contact 11 maintains the contact state reliably by the suction iron pieces 17 and 18,
Short circuit can be performed reliably. To recover from such a situation, move the movable contact 11 to the fixed contact 13.
The movable contact 11 returns to the state shown in FIG. 4a by the force of the spring. Therefore, recovery work can be performed easily.

FIG. 5 shows a circuit diagram of a shorting device according to another embodiment of the present invention, in which the same elements as those in the previous embodiment are designated by the same reference numerals and redundant explanations will be omitted. In this embodiment, the wires are connected so that the phase with an open phase short-circuits the other two phases one after another. For this reason, another sub branch line 9U, 9V, 9W is drawn out from the power supply side branch line 1U, 1V, 1W of each phase, and the movable contact 8U of the U phase sub branch line 9U and the W phase A shorting piece 5U on the U phase side is provided at the fixed contact 7W of the load side distribution line 3W of the U phase load side distribution line 3.
A shorting piece 5V on the V phase side is provided at the U fixed contact 8U and the fixed contact 6V on the V phase sub branch line 9V, and furthermore, a V phase side shorting piece 5V is provided on the V phase load side distribution line 3V fixed contact 6V and the W phase sub branch line 9W. A shorting piece 5W on the W-phase side is provided at the fixed contact 7W. In such a configuration, for example, when the main fuse 2U of the U phase blows, the trigger wire of the trigger fuse 4U of the same phase melts and the trigger immediately protrudes, so that the shorting piece 5U of the same phase contacts the fixed contacts 8U and 7W. . As a result, the W phase is short-circuited with the U phase, so the main fuse 2 of the W phase
W is fused, and the W-phase trigger fuse 4W brings the same-phase shorting piece 5W into contact with the fixed contacts 6V and 7W. As a result, the W phase and the V phase are short-circuited, and the main fuse 2V of the V phase is fused. Therefore, 1
When a phase is open, the other two phases are short-circuited one after another, cutting off the power supply to the load-side equipment. 1st
According to the circuit example shown in FIG. 5 and FIG. 5, short-circuit between phases is performed instead of short-circuiting between three phases, so that the short-circuiting piece can be made smaller and can be operated with a small trigger force.

[Effect of idea]

As explained above, according to the shorting device for protection against phase loss of the present invention, when the main fuse of any one phase blows out, the parallel trigger fuses are activated immediately so that the shorting pieces form a short circuit, so each The power supply from the phase to the load side is cut off, and burnout of the load side equipment can be reliably prevented. At this time, since it is only necessary to move the shorting piece a small distance in the protruding direction of the trigger, it is possible to operate reliably with a small trigger force, and the configuration is not complicated. Further, since the trigger fuse projects an indicator plug at the same time as the trigger projects, the operation of the trigger fuse can be visually confirmed. Therefore,
It becomes possible to use link fuses filled with arc-extinguishing sand, which has an excellent noise-damping effect and does not cause oxidative deterioration.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the short circuit device of the present invention. FIG. 2 is a sectional view showing the configuration of the trigger fuse. FIG. 3 is an explanatory diagram showing the relationship between the trigger and the shorting piece. FIGS. 4a and 4b are explanatory diagrams showing the on and off states of the shorting piece. FIG. 5 is a circuit diagram showing another embodiment of the present invention. Explanation of symbols, 1U, 1V, 1W...branch line (power supply side distribution line), 2U, 2V, 2W...main fuse, 3U, 3V, 3W...load side distribution line, 4,
4U, 4V, 4W...Trigger fuse, 5U, 5
V, 5W...Short circuit piece, 6V, 6W, 6U...Fixed contact, 9U, 9V, 9W...Sub branch line, 10...
... Shorting piece, 11 ... Movable contact, 13 ... Fixed contact, 17, 18 ... Attraction iron piece, 24 ... Shaft, 25 ... Coil spring, 41 ... Insulation cylinder, 42
... Trigger, 43 ... Operation indicator plug, 44 ... Trigger wire, 45, 46 ... Spring, 47 ... Terminal fitting,
48...Lead metal fittings.

Claims (1)

[Claims for Utility Model Registration] (1) A trigger wire that blows out when the main fuse blows out, and a trigger that is held in place by the trigger wire and protrudes when the trigger wire blows out; a trigger fuse provided in each phase so as to be parallel to a main fuse provided in each phase; and an interphase that forms a short circuit between each phase of the distribution line by protrusion of the trigger of the trigger fuse of at least one phase. a short-circuiting means, the interphase short-circuiting means having a shorting piece that moves linearly in the protruding direction of the trigger against elastic force by coming into direct contact with the protruding trigger;
A shorting device for protecting an open phase, comprising a pair of fixed electrodes that are connected to corresponding two-phase power distribution lines and short-circuited by the moved shorting piece. (2) The open-phase protection according to claim 1, wherein the trigger fuse has the trigger at a first end and a fusing indicator line that protrudes when the trigger wire is fused at a second end. short circuit device. (3) The pair of fixed electrodes of the phase-to-phase short circuit means:
Consisting of a first fixed electrode connected to the power supply side of the main fuse of one of the two phases, and a second fixed electrode connected to the load side of the main fuse of the other one of the two phases. The short-circuiting device for protection against open phase according to claim 1.