JPS5923169B2 - Substation equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to substation equipment used in spot network power receiving devices and the like, and relates to an installation configuration that promptly eliminates short-circuit accidents on the secondary side of the transformer.

As an example to which the present invention is applied, a low-voltage spot network system that has recently become popular as a power distribution system for overcrowded cities is shown in FIG. 1, and the prior art will also be described.

That is, power is received from an electric power company's substation 1 through an extra-high electric wire 2 that is sent out in 2 to 3 lines, and is passed through a cable head 3, a disconnector 4, a transformer 5, a protector fuse 6, and a protector breaker 7 for each line. and to network bus 8,
Each line is connected.

Power is supplied from the network bus 8 to each load of the power receiving equipment via a tick-off breaker 9 and a tick-off fuse 10.

At this time, a necessary number of three-phase three-wire circuits 11 and three-phase four-wire circuits 12 are provided depending on the load content.

In such a system, ■ If a short circuit should occur between the secondary winding of the transformer 5 and the power supply side of the protector fuse 6, it would damage the transformer 5 and at the same time cause damage to the primary substation 1 (not shown). This is undesirable because the overcurrent relay is activated and the sending breaker is activated, causing a power outage to that line, which also causes a power outage to the lines of other consumers connected to that line.

(2) Furthermore, even if the protector fuse 6 is placed directly below the windings of the transformer 5 and the insulation is reinforced with an insulating jacket, such as insulating tape, the insulation is not perfect and it is impossible to completely eliminate short-circuit accidents.

Furthermore, since fuses generate a lot of heat, cooling fins are often installed near the terminals to increase heat dissipation, and the shape is generally complex, making it difficult to strengthen the insulation by adding an insulating jacket, and it is difficult to strengthen the insulation by applying an insulating jacket. It would be expensive to strengthen the insulation using

These will be further explained with reference to FIGS. 2 and 3 showing a more specific conventional panel configuration.

In general, when a spot network is configured as a panel and installed on a building, depending on the building conditions, it is generally necessary to connect the cable head 3 to the special high-speed side 35 of the transformer 5, and the protector fuse 6 to the A separate type system in which the low-pressure side 36 up to the off-fuse 10 is arranged separately and connected by a bus duct 30, and a collective type system in which they are integrated as shown in the arrangement shown in Fig. 3 are adopted. ing.

In FIG. 2, the extra high-speed side 35 is further provided with a cable head 3 and a disconnector 4 on the front side 31, and a transformer 5 on the rear side 32, and in FIG.
, protector fuse 6, protector breaker 7, network bus bar 8, tick-off breaker 9, and tick-off fuse 10 are usually provided on the front side 40 and the transformer 5 on the rear side.

When configured in this way, first of all, in the separated type, as shown in Fig. 2, there is a distance between the secondary side of the transformer 5 and the protector fuse 6, and the bus duct 30 connects that distance, so the number of parts is large. This increases the number of causes of accidents.

In other words, since the protector fuse 6 is further away from the secondary side of the transformer 5, its protection range is limited.

In the case of the collective type, as shown in Figure 3, the extra high-voltage side and the low-voltage side are integrated, so the distance from the secondary side of the transformer 5 to the protector fuse 6 is short, and the cause of the accident is the separated type. Even if the protector fuse 6 is located directly below the transformer 5, there will still be some unprotected range of the protector fuse 6, which is difficult to completely eliminate.

In addition, in order to place it economically, it is necessary to install it inside the panel, which is far away from the front and back, and it is necessary to enter the panel for replacement in the unlikely event that the fuse blows out or for daily visual inspection. Generally undesirable.

The purpose of the present invention is to minimize the unprotected area on the secondary side of the transformer,
An object of the present invention is to provide substation equipment that minimizes the spread of a short-circuit accident on the secondary side of a transformer to the primary side.

That is, to summarize and explain a typical embodiment of the present invention, in the secondary of a transformer, one end of each winding is connected to the load side and the other end is connected together via a fault current blocking element, such as a fuse. By pulling out the neutral phase, the fuse provides protection against short circuits and ground faults on the secondary side, including the transformer windings, and at the same time, it also prevents short circuits on the secondary side of the transformer. The goal is to eliminate ground faults in a very short time using fuses, and to minimize the impact on the primary side.

On the other hand, in terms of specific means of construction, the fuse is mounted on a panel structure so as not to be affected by the vibrations of the transformer, and by connecting it to the transformer with a vibration-mitigating conductor, the life of the fuse is prevented from deteriorating due to vibration. Installation of fuses to avoid
This is for configuring the board.

Hereinafter, typical embodiments of the present invention will be described with reference to FIGS. 4, 5, and 6-7.

Figure 4 shows an example of a spot network system to which the fuse connection method of the present invention is applied, and Figures 5 and 6 show fuses supported by a panel structure so as not to be affected by vibration of the fuse transformer, and vibration-reducing conductors. 2 shows an embodiment of a transformer chamber of a closed switchboard connected to a transformer via a side view in a and a rear view in b; FIG.

Among them, Figure 5 shows a case where the transformer cooling fan is installed separately from the transformer on the front side, and the load on the secondary side of the transformer is drawn from the panel ceiling. This is applied to the transformer room on the back side 32 of the extra-high side 35 of the separated type 2.

On the other hand, Figure 6 shows a case where the cooling blower for the transformer is built into the transformer case itself, and the drawer for the load on the secondary side of the transformer is penetrated from the bottom to the front side. It is applied to the transformer room on the rear side 41 of the collective type shown in the figure.

FIG. 7 shows a detailed explanatory view of the fuse chamber 51 in FIG. 5 and the fuse chamber 51 in FIG.
- represents a plan view showing the A arrow view.

Next, each part will be explained in detail. In FIG. 4, one end 16, 18, 20 of the secondary winding of the transformer is drawn out to the load side and connected to the protector breaker I.

On the other hand, the other ends 15, 17, and 19 are connected to form a neutral point 22 via a protector fuse 6, which serves as a fault current blocking element.

Then, this neutral point 22 is directly grounded, and the neutral phase 21
A spot network system is configured by connecting the lead-out network bus 8 to the network bus 8.

The other configurations are the same as those in FIG. 1 described above, and corresponding parts are denoted by the same reference numerals and explanations will be omitted.

With this configuration, since the neutral point is directly grounded between the neutral point 22 and each protector fuse 6, the normal potential is zero, and even if a phase-to-phase short circuit or ground fault occurs, no fault current will occur. (It is safe and does not require reinforcement of insulation or measures to prevent human contact.

Next, the neutral point side 15 of each winding of each protector fuse 6,
Looking between 1γ and 19, even if a temporary short circuit or ground fault occurs, the potential is still zero, so no fault current will occur and it is safe.

However, for example, if a short circuit or ground fault occurs at load terminals 16, 18, and 20 of the transformer with a three-phase short circuit between them, a fault current will flow, but in such a case, normally the fuse unit Since the cable and its connecting conductor are covered with a closed material and there is no risk of foreign matter intruding, there is no need to strengthen the insulation or take measures to prevent human contact with this part.

In the event of a ground fault or short circuit accident between the load terminals 16, 18° 20 of each winding of the transformer and up to the power supply side of the take-off fuse 10, the protector fuse 6 installed at a new position will promptly melt and cause an accident. At the same time as cutting off the current, it is possible to expand the protective envelope of the protector fuse in order to minimize the time for the current to spread to the primary side of the transformer 5.

Furthermore, the protector fuse 6 naturally exerts its protective function even in the event of a ground fault or short circuit accident in the secondary winding of the transformer.

This is a new feature that could not be achieved with the conventional system shown in Figure 1.

By arranging the protector fuse 6 in the position configuration shown in FIG. 4, the above-mentioned features can be obtained. However, if the fuse is exposed to vibration due to its internal structure, there is a risk that the life of the fuse will deteriorate. In the case of actualization, it is necessary to take measures to alleviate this vibration, and as one means of this, a typical embodiment in which the present invention is applied to a transformer room using a dry type transformer will be described below.

In the side view of Figure 5a, the board is on the front side 31 and the back side 32.
The transformer 5 is housed on the back side 32 of the transformer 5.

The electric path is introduced from a disconnector (not shown) to the terminal 56 and connected to the primary conductor of the transformer 5 via a vibration-reducing conductor, such as a flexible lead 58.

Each load side terminal 16, 18, 20 of the secondary winding of the transformer 5
is led out of the panel by a bus duct 30 or the like via a flexible lead 5T.

On the other hand, the neutral point side terminals 15, 17, and 19 are connected to the terminal of the protector fuse 6 of the fuse unit 51 via a flexible lead 55.

After connecting the other terminals of the protector fuse 6 to form a neutral point, the neutral wire 21 is similarly drawn out from that part via the flexible lead 55 and supported at an appropriate position by the transformer 5. Thereafter, like the other voltage sums, it is drawn out via the flexible lead 57 through the bus duct 30 or the like.

Here, the fuse unit 51 is fixed to a rear frame 54 that is removed when the transformer 5 is pulled out, and when the frame is removed, the fuse unit 51 can be removed while attached to the frame 54 by removing the flexible lead 55. Therefore, even if the fuse unit 51 is installed in the center of the back, it does not impede the conventional workability of inserting and removing the transformer.

This fuse 6 generally generates a large amount of heat (it is necessary to consider its cooling, but the ventilation path shown by the dotted line arrow in the figure of the transformer 5, that is, the cooling 52 that is first sent by the blower installed in another room The wind flows through the transformer case, cools the transformer windings and core, passes through the panel, and is exhausted to the outside of the panel through an exhaust duct 50 installed in the ceiling. Cooling can be easily achieved by providing a ventilation hole in the rear door to allow ventilation into the fuse unit 51, as indicated by a solid arrow 53 in the figure.

In addition, a wind guide for passing cooling air with increased pressure from the transformer 5 from the lower part of the fuse unit 51 to the case of the transformer 5 is formed with bellows or the like so that the vibrations of the transformer 5 are not transmitted to the fuse unit 51. Fuse unit 5
1 and discharged to the transformer room and rear ventilation port, it is possible to achieve more efficient cooling through forced ventilation.

In any case, at the same time as cooling the transformer to prevent high-temperature hot air from entering the fuse unit, it is also possible to minimize heat transfer by pasting a heat insulating material on the inside of the case of the fuse unit 51, if necessary.

FIG. 6 shows an embodiment in which a cooling blower 61 for the transformer 5 is built into the transformer itself, and its intake port is provided on the back surface.

Further, this is an embodiment in which the winding load side of the transformer 5 is introduced from the transformer chamber 41 to the front side 40 in the direction of the arrow 60 via the flexible lead 57.

Other configurations can be explained in the same manner as in FIG.

Next, to explain the fuse unit 51 in more detail, as shown in FIG. The door 70 and the fuse unit 51 are movable as a unit.

In other words, when removing or inserting the transformer, the work can be carried out without any trouble by removing the integral frame 54.

Therefore, remove the door 70, then remove the unit, and then remove the frame 5.
Compared to the case where the transformer is put in and taken out through several steps, such as removing the door 4 and putting the transformer in and out, it is possible to improve work efficiency by eliminating the need for door adjustment.

The conductive path within the fuse unit 51 will be explained in detail below.

Terminals 15, 17, 1 on the neutral side of each winding of the aforementioned transformer
9 is suitably supported on the transformer.

This dampens the vibrations of the transformer via the flexible lead 55 and is connected to one terminal of the protector fuse 6 via the conductor 19 supported by insulating supports 74 and 75.

In that case, the insulating support 14 is the fuse unit case 51
The hot air from the transformer room forms the back side of the fuse unit 51.
In the same manner as the side surrounding case 51, consideration is given to preventing the inside of the case from entering.

Furthermore, a conductor 80 is connected from the other end of the protector fuse 6.
They are each extended to the transformer side via a short-circuit piece 73, and a neutral point can be formed by short-circuiting the voltage sum with a short-circuit piece 73 in the middle.

A portion of this neutral point is connected to the neutral wire 21 supported by the transformer via a flexible lead 55, and routed in any direction.

To support the fuse 6, conductors 79 and 80 connected to the terminals of the fuse 6 are connected to an insulating support 7, as already shown in FIG.
5 from above and below, and sandwiched in the lateral direction by interphase insulators 78 and fuses 6, economical and rigid support is possible.

71 is a ventilation opening leading to the fuse unit 51 provided in the door 70;
It is constructed by welding to the back side of 0.

In addition, a sponge 77 having some elasticity and airtightness is placed between the door 70 and the unit 51 around the ventilation lower 1 of the door.
By attaching it to the side, consideration is given to preventing hot air from the transformer room from entering the unit 51 when the door 70 is closed.

With this configuration, hot air from the transformer room enters the unit room and is not affected by the rise in temperature of the fuse, and cold air from outside can be naturally ventilated through the ventilation lower 1 of the door 70, thereby cooling the fuse 6. becomes possible.

If necessary, it is also possible to screw the protective cover 81 to the case 51 so that the live part of the fuse 6 cannot be easily touched when the door 10 is opened.

These features prevent the vibrations of the transformer from being transmitted to the fuse, making it possible to guarantee the life of the fuse.

In addition, the fuse unit 51 can be removed at the same time as the frame 54, so that work to take in and take out the transformer is not obstructed.

Furthermore, the fuse can be inspected at the rear within easy reach of human hands, making maintenance and inspection work easier.

As described above, according to the present invention, one end of each of the transformer secondary windings is commonly connected via the fault current interrupting element to form a neutral point, so that all Accidents can be eliminated in a very short amount of time, and power outages in the upper system and damage to transformers can be minimized.

[Brief explanation of the drawing]

Figure 1 is a system diagram showing a conventional general spot network system, Figure 2 is a perspective view showing a separate board configuration of a general spot network, and Figure 3 is a collective board configuration of the same spot network. A perspective view, FIG. 4 is a system diagram showing a spot network system employing an embodiment of the substation equipment according to the present invention, and FIGS. FIGS. 7a and 7b are a side view and a rear view respectively showing an embodiment of the present invention, and FIGS. 7a and 7b are a plan view and a front view showing an enlarged fuse unit used in the present invention. 5...Transformer, 6...Fault current interrupting element, 22...Neutral point, 55...Vibration mitigation conductor.

Claims (1)

[Claims] It has a transformer with the 12th side connected in a star shape, and the 2
A fault current shielding element is interposed between each phase winding on the next side and the neutral point, and the neutral point is grounded, and the end of each phase winding on the side opposite to the neutral point is connected to the load side. Substation equipment connected to electrical circuits.