JPS60111406A - On-load tap changing transformer - Google Patents

Abstract

PURPOSE:To prevent the generation of flashover without attaching a special device as well as to obtain an on-load tap changing transformer with which load loss can be reduced by a method wherein the potential difference generating between the contact points of a subchanger is made smaller. CONSTITUTION:The loose tap winding 8 wound around outside of a high tension main winding 3 and arranged on the upper and the lower sides in a shifting manner is arranged on the A and B blocks of 8A and 8B, and a close tap winding is arranged symmetrically on the A and B blocks of 9A and 9B in splitted form with the U- terminal of the center connecting point of a high tension main winding 3 as the center point. The upper and the lower blocks are connected in parallel and they are constituted in such a manner that they can be connected to an on-load tap changer 10. These upper and lower blocks are symmetrically formed with each other, and they are alternately arranged in such a manner that the positions of the split blocks 8A and 8B of the loose tap winding and the split blocks 9A and 9B of the close tap winding are transferred in vertical direction, and the split blocks 8A and 8B, and 9A and 9B are series-connected separately. Through these procedures, the potential Ex of the close tap winding 9 when a switching operation of the dislocation changer 10 is performed is reduced, and a high resistor and an electrostatic shielding used in the conventional device are unnecessitated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an on-load tap-changing transformer having an improved transformer winding having an on-load tap-changing device with a sub-switcher.

[Technical background of the invention and its problems]

In the case of tap-changing transformers with stage insulation, the line terminals are pulled out from the center of the winding for high-voltage windings, and the tap changer is installed on the neutral point side where the insulation is low, thereby increasing the number of taps. ing. A typical winding configuration is shown in FIG.

Figure 1 shows a low-voltage winding 2 wound around an iron core leg l, a high-voltage main winding 3 completely wound around the outside of the core leg l, and a tap winding 4 divided into upper and lower parts.
are arranged on the outside of both the upper and lower ends of the high-voltage main winding #J3. The high-voltage main winding 3 is divided into upper and lower parts, and its center connection point is connected to the line terminal U, its upper and lower ends are connected, and the tap winding 4 is connected in series by a polarity switch 5.

In such a winding configuration, the tap winding @4 is electrically disconnected from the high-voltage main winding 3 during the switching operation of the polarity switch 5, and at that time the tap winding 4 assumes a potential that is different from the operating potential. It turns out.

The potential of the tap winding 4 is related to the capacitance between the winding portions that are spatially close to each other or the tank wall, and the larger the capacitance with the adjacent winding portions, the closer the potentials are. The value is close to the average potential of the winding part.

In the winding arrangement shown in Figure 1, the capacitance between the high voltage main winding 3 and the tap winding 4 is much larger than the capacitance between the tap winding 4 and the tank wall (Nirube). The potential of the tap winding 4 is close to the average potential of the high-voltage main winding 3, which is a winding portion close to the tap winding 4, and is large.

As a result, during the switching operation of the polarity switch 5, the contacts (P) of the polarity switch 5 are separated or approached.

and P, or between P and 21 (2). When this undesirable flash occurs, the high voltage winding (2 is an abnormal circuit), pressure is generated and the insulation of the winding is damaged. This may lead to destruction or damage to the switch contacts (Second).

In order to avoid such a situation, as shown in Figure 1 (2), there is a It is necessary to install resistor 6.

However, the required high potential control resistor 6 must be capable of withstanding not only the voltage required for the windings but also severe test voltages and lightning impulse voltages. It is extremely expensive, and has the disadvantage that the tank becomes large to accommodate the high resistor 6, the external dimensions of the transformer become large, and the weight becomes heavy.

Instead of the high resistor 6 (2. As shown by the dotted line in Figure 1, an electrostatic shield 7 with one end connected to the movable contact pot 2 is installed between the high voltage main winding 3 and the tap winding 4, There is also a method in which the potential from the high-voltage main winding 3 is reduced by an electrostatic blocking effect.

However, this method also requires an expensive electrostatic shield 7 because the insulation structure at the terminal part is complex, and the dimension G between the high-voltage main winding 3 and the tap winding 4 is increases, and the outer diameter of the tap winding 4 increases accordingly, resulting in increased loss and poor transformer performance.
The 1272 size also increases, resulting in an increase in the external dimensions and weight of the transformer.

[Purpose of the invention]

The purpose of the present invention is to reduce the potential difference generated between the contacts of the sub-switcher, to prevent flashovers from occurring without installing special equipment, and to provide tap switching during load that reduces double-load loss. Providing a transformer (there are two).

[Summary of the invention]

In addition to using the sub-switcher as a polarity switch as described above, there is also a method of using the sub-switcher as a shift switch, and its winding configuration and connections are as shown in FIG.

That is, instead of the tap winding 4, a coarse tap winding 8 and a fine tap winding 9 are provided. The coarse tap winding 8 (the two are always connected to the high voltage main winding 30, so their potential is the operating potential and no difference occurs.However, the fine tap winding 9 is connected to the high voltage main winding 30 at all times, so no difference occurs. It takes a potential different from the potential (to simplify the explanation below, it will be expressed as C: this potential fix).

The present invention uses a method of using this transposition switch 10 to reduce the potential Ex by appropriately arranging the coarse tap winding 8 and the fine tap winding 9. This eliminates the need for an electrostatic shield and reduces load loss at the lowest tap.

[Embodiments of the invention]

An embodiment of the present invention will be explained below from FIG. Tap windings 8'iA, H block 8A, 8B, close tap winding 9
The upper and lower blocks are each divided into blocks 9A and 9B of A and H, and the upper and lower blocks are arranged vertically symmetrically around the center connection point U terminal of the high-voltage main winding 3. and on-load tap changer (=configured so that it can be connected).

Each of these blocks is vertically symmetrical as shown in FIG. The divided blocks 8A and 8B and 9A and 9Bi are arranged separately (: in series (two connected).

Even if the coarse tap winding 8 and the fine tap winding 9 are divided and connected in this way, there will be no change in the voltage adjustment due to tap switching (although there will be no change in the voltage adjustment due to the two, the potential Ex mentioned above will be significantly smaller, so Explain.

The switching operation of the transposition switch IO is such that the neutral point terminal 0 is connected to the tap contact To, that is, P, so at this time, the axial terminal P of the close tap winding 9 is connected. However, the high voltage main winding 3
and the coarse tap winding 8, or from the axial terminal P1 of the coarse tap winding 8, and at that time the fine tap winding 9 assumes a potential Bxf different from the operating potential. .

In this case, since the potential of the neutral point terminal 0 is zero, the potential of the ten tap contacts, that is, the terminal Pl, is also zero.

Therefore, as shown in FIG. I understand.

As shown in Figure 3, the C2 divided block 9A is sandwiched between the divided blocks 8A and 8B, so the capacitance between the divided block 9A and the divided blocks 8A and 8B is the same as that of the divided block 9A and the high voltage main The capacitance between the winding wire 3 and the adjacent winding portion (the value is larger than 1).

Since the divided block 9B is placed in contact with the divided block 8Bl, the capacitance therebetween is larger than the capacitance (-) between the divided block 9B and the adjacent winding portion of the high voltage main winding 3.

From this relationship, the thicker the potential Ex, the greater the influence of the potential E8, which has a smaller value, and the greater the influence of the potential E3, which has a larger value.
The influence of this becomes small, and the potential Ex eventually becomes a small value. By the way, in the conventional figure 1, only the potential E3, which has a large value, is related (-), so the potential of the tag winding 4 is close to the potential E3 and is large, so the figure 2 of the present invention has a large value. It can be seen that the value is (−) small.

As explained in the above embodiments (2), the present invention has a potential E
Since x is a much smaller value than the conventional one (1),
When the potential switch 10 is activated, the contacts that are disconnected or approached (between Po and 21 or between Po and P).

(between), undesirable flashover will not occur. Therefore, the high resistor 6 or the electrostatic shield 7 for preventing flash-flash is unnecessary, and all of the above-mentioned drawbacks of the prior art are eliminated.

Furthermore, when the voltage of the high-voltage winding is the lowest, that is, the load loss at the lowest tap where the loss is maximum is much smaller than in the conventional case (2), so the cooling device can be made smaller by that amount.
It will also help improve the efficiency of transformers. Regarding the load loss at the lowest tap, in the case of the conventional polarity switch shown in Figure 1, po and P! .

The 0 and TI contacts are connected respectively, and the load current flows between the high voltage main winding 3 and the majority of the tap winding 4, from P2 to T5, so the sum of the number of turns of the windings through which the current flows is This increases the resistance loss. The leakage flux generated by the tap winding 4 (the stray loss caused by the leakage flux is also large).

In the case with a transposition switch (2, po and P!, 0 and Ts contacts are connected respectively, and the load current flows through the high voltage main winding 3 (= the same as in the case with a polarity switch), Current does not flow in the coarse tap winding 8, and in the fine tap winding 9, only the l tap between Po and T@ flows (= current flows, but does not flow in the other parts between l and Ts. Therefore, the sum of the number of turns of the winding through which current flows is small, and resistance loss is reduced.

Since no leakage flux is generated by the coarse tap windings 8 and less leakage flux is generated by the close tap windings 9, stray loss is also reduced.

In Fig. 3, when the coarse and fine tap windings 8 and 9 are each divided into four parts, two Cs are shown.
Even number of parts (may be divided into two).

As the number of divisions increases, the capacitance between the coarse tap winding 8 and the fine tap winding 9 increases, and the voltage Ex is influenced more by the average potential of the coarse tap winding 8. As a result, the potential Ex becomes a smaller value.

Figures 2 and 3 show a single-stage transposition switching system with one coarse tap winding 8, but a multi-stage type with two or more coarse tap windings 8, which allows for a large number of tap points. It can also be used in the transposition switching method.

In Figure 3, the upper half and lower half of the coarse tap winding 8 and the fine tap winding 9 are connected in parallel (two connections are made and one load tap cutter is used, but the upper and lower halves are connected in parallel). Separate circuits (-1
If a total of two on-load tap changers (21) are used, a large current transformer (2) can also be applied.

It can also be applied to a split-winding transformer in which the low-voltage winding 2 is divided into upper and lower parts (: divided into two separate circuits C) and used, and a medium-voltage winding is placed between the low-voltage winding 2 and the high-voltage main winding 3. It can also be applied to three-winding transformers.

Although the description has been made for a stage-insulated star-connected transformer, which has many applications, it can also be applied to star-connected or triangularly connected transformers that are not stage-insulated.

〔Effect of the invention〕

As described above, the structure of the present invention (i.e., a simple structure that eliminates the need for an expensive high-resistance device that requires mounting space or an electrostatic shield at all) is highly reliable, compact, lightweight, and inexpensive. Furthermore, it is possible to provide an on-load tap changeover transformer that can reduce the load loss at the lowest tap time 1: and is also excellent from the viewpoint of energy saving.

[Brief explanation of the drawing]

Figure 1 is a wiring diagram showing the winding arrangement and connections of a conventional on-load tap-changing transformer, and Figure 2 is a wiring diagram showing tap winding connections and potential differences in a transposition switching type on-load tap-changing transformer. , FIG. 3 is a wiring diagram showing the winding arrangement and connections thereof in one embodiment of the on-load tap-changing transformer of the present invention. ■... Iron core leg 2... Low voltage winding 3... High voltage main winding 4... Tap winding 5... Polarity switch 6... High resistor 7... Electrostatic shield 8・
...Coarse tap windings 8A, 8B... Division A, B blocks of coarse tap windings 9... Fine tap windings 9A, 9B... Division A, B blocks 1 of arm tap windings.
0 ... Transposition switch E, ... E, ... Potential difference agent Patent attorney Noriyuki Chika (and 1 other person)) 0 ・ ・ ・ Medical N Law

Claims (1)

[Claims] A low voltage winding, a high voltage main winding, and a high voltage tap winding consisting of a coarse tap winding and a fine tap winding are wound around the iron core leg from the inside, and the high voltage main winding is wound in upper and lower distribution, Its central connection point is connected to the line terminal, and its lower end is connected in series to the coarse tap winding, and the fine tap winding is connected to the coarse tap winding or the high voltage main winding via a shift switch. In an on-load tap-changing transformer connected in series, the coarse tap winding and the fine tap winding are each divided into an even number of blocks;
The coarse tap winding block and the fine tap winding block are on the top,
lf! I made it so that it was arranged alternately downward! jgL
on-load tap-changing transformer.