JPH0239506A - Transformer device for distribution - Google Patents

Abstract

PURPOSE:To make it possible to do three-phase distribution of neutral point grounding with simple constitution by connecting one end of a first grounding wiring with one end of a second grounding wiring so as to ground them in common, and connecting the other end of the first grounding winding with a second tap, and connecting the other end of a second grounding winding with a first tap. CONSTITUTION:One terminal Ug of a first grounding winding Cug and one terminal Vg of a second grounding winding Cwg are connected in common, and the common connection point O is connected to a bushing terminal B0 for grounding. The tap U2t of the secondary winding Cu2 of a unit transformer M1 is connected to the other terminal Vge of the grounding winding Cwg of a unit transformer M2, and the tap V2t of the secondary winding Cw2 of the unit transformer M2 is connected to the other terminal Uge of the grounding winding Cug of the unit transformer M1. If it is defined that voltage between terminals U2, V2 and W2 is E2, and the voltages to ground are U20, V20 and W20, these sizes E20 are equal from the relation of the number of turns, which has the phase difference of 120 deg., and E2=3<1/2>E20. That is, the neutral point of the terminals U2, V2 and W2 is zero.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a power distribution transformer.

[Prior art] According to the provisions of Article 23 of the Electrical Equipment Technical Standards, in transformers that connect high-voltage distribution circuits or special high-voltage distribution circuits and low-voltage distribution circuits, unless equipped with a cross-contact prevention plate, If the working voltage exceeds 300V, the neutral point of the transformer must be grounded. Therefore, when supplying three-phase power with 400■ class power distribution, a distribution transformer placed on the power supply side is used as a three-phase power supply with a star connection on the secondary side (400■ class side) and a neutral point drawn out. A transformer was used.

Figure 11 is a vector diagram showing the configuration of a conventional three-phase power distribution transformer in which the primary side is delta-connected and the secondary side is star-connected. to W phase primary winding, and U1' to W phase primary winding.
Lo indicates the primary terminal of each of the three phases. Furthermore, Cu
2'- to Cw2- indicate a three-phase secondary winding, U2° to W2' indicate a three-phase secondary terminal, and O' indicates a neutral point.

In this specification and drawings, all vectors mean voltage vectors.

In this specification, 100 ■ class voltage, 200 ■ class voltage,
400 V class voltage refers to the general output voltage range of transformers used for low-voltage power distribution in Japan, and is 100 to 110 V (-100 V to 100 V for boat fishing voltages).
05V is used), 200 to 220V (- 210V is used for boat fishing), 400 to 440V (-
Boat fishing voltage is 420V. 1. (440V is used).

In addition, the present applicants proposed a power distribution system shown in FIG. 12 in a previous application (Japanese Patent Laid-Open No. 62-25826). In the power distribution system in this earlier application, the primary winding C is used as a power transformer.
u1'' and a secondary winding Cu2'' whose terminal is drawn out from the midpoint, and a primary winding CW1'' and a secondary winding CW2'' whose terminal is drawn out from the midpoint. Using two single-phase transformers, the primary windings Cu1'' and 0w1'' of both vehicle phase transformers are V-connected. and secondary winding C
The midpoint of 112JJ and 0w2'' is connected to form a neutral point O'', and this neutral point is grounded.

With the above configuration, it is possible to obtain two circuit voltages of 400/200 V class between the terminals of the secondary windings Cu2" and 0w2" connected in an X-shape and between each terminal and the neutral point. Can be done. At the same time, between the two terminals of one (upper end) of the secondary windings Cu2'' and CW2'' and the three terminals of the neutral point, and Cu2''
Two circuits of three-phase 20OV class voltage can be obtained between the other (lower end) two terminals of CW2'' and the three terminals at the neutral point.

In addition, the applicants have filed another prior application (Japanese Patent Application No. 138937/1986).
proposed a three-phase power distribution transformer shown in Figure 13. Figure 13 shows only the secondary side in vector form, and this three-phase transformer consists of a star-connected or delta-connected three-phase primary winding (not shown), and a first three-phase secondary winding (not shown). Next winding Cu
21 to CW21, and second three-phase secondary windings Cu22 to 0w22. and the first three-phase secondary winding CU21 to 0w21 and the second three-phase secondary winding Cu2.
2 to CW22 are connected in delta so that the phase difference between the voltages appearing between the corresponding terminals of the three-phase terminals drawn from each is 60 degrees, and the directions of the phase connections are different. Connect one terminal of the three-phase secondary winding (U21 in the example of FIG. 13) and one terminal of the second secondary winding (W22 in the example of FIG. 13) to the terminal of the first secondary winding. and the terminal of the second secondary winding are grounded so as to be vector-symmetrical with respect to the grounding point.

With this configuration, a three-phase voltage of, for example, 200V class can be obtained between the terminals of the first secondary windings Cu21 to CW21 and the terminals of the second secondary windings CU22 to 0w22 which are connected in delta, and at the same time, Line terminal LJ22. in a symmetrical vector position with respect to the ground point. Between V21 and V22.
A 400V class voltage can be obtained between W21. In this case the second secondary winding CLI2 connected in delta
The 200V class three-phase voltage obtained from 2 to 0w22 is:
Delta-connected first secondary windings Cu21 to CW2
This is a voltage whose phase is 60 degrees ahead of the 200V class three-phase voltage obtained from 1. Further, the 400V class voltage represented by the vector directed from the terminal V21 to U22 is a voltage whose phase is delayed by 120 degrees from the 400V class voltage represented by the vector directed from the terminal V22 to the terminal W21.

In addition, as shown in Special Publication No. 47-9493, 2
A V-connection transformer is known in which two transformers are connected to one another and a neutral point is grounded by combining this with a handle. Figure 14 is a vector diagram showing the configuration of the secondary side of this V-connection transformer.As shown in Figure 14, this transformer consists of two terminals with a midpoint terminal drawn out from the midpoint. Connect the transformer winding TIT2 (or T,
1) Connect a reactor L between the terminal T (or R) on the opposite side of the S terminal and the terminal a (or b) pulled out from the midpoint of the other transformer winding TI (or T2). Then, extend a tap from the point where the winding ratio is 2:1 when viewed from terminal T (or R) of reactor L, connect this tap to terminal E, and use this terminal E as the ground terminal. .

According to the transformer shown in FIG. 14, the secondary terminals R, S,
T, each voltage to ground according to Electrical Equipment Technical Standards No. 177
It is possible to obtain a three-phase 200V class voltage by keeping the ground voltage of the indoor electrical circuit below the limit value of 150V specified in the article, and the midpoint terminal a of the windings TI and T2.

By connecting b to separate neutral wires, two 200/100 V class single-phase three-wire power distribution circuits can be obtained using terminals R, a, S and terminals T, b, S. Furthermore, in this transformer, since the neutral point of the three-phase vector of terminals R, S, and T is grounded, Article 23 of the Electrical Equipment Technical Standards is satisfied even if the secondary side circuit is 400V class.

Furthermore, Japanese Utility Model Application No. 52-138219 proposes a transformer shown in FIG. 15. In Fig. 15, lr is the iron core, Pr is the primary winding, Se is the secondary winding, Te is the tertiary winding,
Xi, Yl, Zl are primary side terminals, ×2, Y2,
Z2 is a secondary side terminal, and N is a ground terminal. In this transformer, tertiary windings are provided in two of the three phases, these are connected in reverse, and one terminal on the tertiary side is connected to one terminal on the secondary side which is connected in delta. The other terminal on the tertiary side is the ground terminal N.

Although the transformer shown in Fig. 15 was not proposed for 400V class power distribution, by specifying the winding ratio between the secondary winding and the tertiary winding, the grounding point N can be connected to the secondary circuits X2, Y2.
, it can be used as the neutral point of the vector of the Z23 phase, so even if the secondary circuit is 400V class, the Electrical Equipment Technical Standards 2
It is considered that Article 3 is satisfied. Also, although not shown in this proposal, if terminals are drawn out from the midpoint of each of the three-phase secondary windings to create, for example, an internal delta connection, then the three-phase four-phase
It is possible to obtain a 00V class voltage and three circuits of 400/200V class single-phase three-wire circuit, and a 200V class 3 It is also possible to obtain phase voltages.

[Problems to be solved by the invention] The conventional three-phase transformer, which combines three single-phase transformers, inevitably increases in size and has problems with structural stability and aesthetics when mounted on poles. there were.

If two transformers are combined to form a three-phase transformer as shown in FIG. 12 or FIG. 14, the size of the tank can be reduced, but in the configuration shown in FIG. Total voltage on the next side (the larger voltage in a system where two types of secondary voltage are supplied by selecting the distribution line, E
In 2), there is a problem that the three-phase voltage cannot be directly obtained.

Furthermore, the configuration shown in FIG. 14 requires a reactor and has the problem of increased grounding impedance.

Further, studies are underway to increase the current 100V class power distribution voltage to 200V class, but in this case, there will be no major problems on the power distribution system side, and it is expected that it will not be difficult to realize this as long as the load side can take measures.

When changing the distribution voltage to 200V class, the 200V class side of the currently popular 200/100 V class single-phase 3-wire circuit will be used, so the 200V class voltage at the output terminal of the transformer will be 210V. It is thought that.

However, as the next step, especially in areas with high load density, there is an increasing need to upgrade the current 200V class distribution voltage to 400V class, and 400/20OV class is expected to be the future distribution voltage. ing. In this case, it will be necessary to review Article 177 of the current Electrical Equipment Technical Standards, but as a transformer used for this distribution system,
Considering the simplicity of the configuration and the high utilization rate of the transformer, it is the first choice.
A three-phase transformer with a delta/star neutral point extraction structure shown in Figure 1 is considered suitable.

However, in this case, the voltage value on the 200-class side becomes a problem. In other words, in the case of Fig. 11, the 400V class voltage is applied to the secondary terminal U2.
200V class voltage is obtained between the secondary terminal U2° and W2°.
In this case, if the voltage between the terminals of the transformer is 420V (currently the lower of 440V and 420V applied in the shell), then
The voltage between terminals U2°~W2' and the neutral point is 420/4
-242V, assuming that the voltage drop to the load point is about 5%, the voltage at the load point between the terminal and the neutral point is 23V.
The voltage will be approximately 0V. However, the load side equipment that is compatible with the 200■ class distribution voltage that is currently being considered is the current 200■ class.
It is thought that many of them have a rated voltage of 200V, similar to V-class load-side equipment.

However, there are many technical difficulties in using load-side equipment rated at 200V at 230V.

In this way, in the wiring shown in FIG. 11, when the voltage between the secondary terminals is set to the 400V class voltage defined in this specification, the voltage between the secondary terminal and the neutral point is set to the 200V class voltage defined in this specification. The voltage range will be exceeded, causing problems with the load equipment.

In order to solve such problems, it is necessary to perform single-phase three-wire power distribution in which the 200V class voltage is accurately set to 400V class voltage 172.

Therefore, a tap is provided in the secondary winding to obtain an appropriate 200V class voltage, and 200V@W is installed between this tap and the neutral point.
It is also possible to obtain voltage, but in this case, it is inevitable that the transformer and distribution line would be complicated.

In addition, in the transformer shown in Figure 12, the voltage between the neutral point and the secondary terminal is 172 on the full voltage side, which is convenient, but as mentioned above, the three-phase voltage at full voltage cannot be directly obtained. There's a problem. The transformer shown in FIG. 13 also has a similar problem.

Furthermore, the configuration shown in Figure 14 is convenient in that it can obtain the full voltage and the total voltage of 172 for both three-phase and single-phase, but as already mentioned, this configuration requires a reactor and the ground impedance is low. There are concerns that it will get bigger.

Furthermore, if the method shown in Figure 15 is applied and the secondary side is inscribed delta connection, it is possible to obtain the total voltage and 172 voltages for both three-phase and single-phase, but in this configuration, the three legs of the three-phase transformer Manufacturing the transformer is complicated, such as winding the tertiary winding around the middle two legs.

The purpose of the present invention is to perform three-phase power distribution with neutral point grounding in accordance with the provisions of Article 23 of the Electrical Equipment Technical Standards without complicating the configuration or using a reactor. Accurately 400V class voltage of 172
An object of the present invention is to provide a power distribution transformer device capable of performing single-phase three-wire power distribution.

Means for Solving the Problem] In the transformer of the present invention, as shown in FIG. 3 (A> or (B)) showing an embodiment thereof, a first unit transformer M1 and a second unit A transformer M2 is provided, and these transformers are housed in a common container Ta.

As seen in FIG. 1, the first unit transformer M1 includes a first primary winding Cu1, a first secondary winding Cu2, and a first
A first grounding winding CIJ (+) with a total number of turns N of 173 turns of the secondary winding CLI2 of
The first tap U2t is pulled out from a point (2/3)N turns from one end of u2.

The second unit transformer M2 has a second primary winding CW1 having the same number of turns as the first primary winding, and a second secondary winding CW2 having the same number of turns as the first secondary winding. , second secondary winding C111
a second grounding winding C with a total number of turns N of 2 and 173 turns;
W(I), from one end of the second secondary winding Cw2 to (2
The second tap V2t is drawn out from the point of /31N turn.

One end of the first primary winding Cu1, one end of the second primary winding CW1, and the connection point between the other end of the first primary winding Cu1 and the other end of the second primary winding Cw1. 1st to 3rd respectively from
The primary side terminals U1, Vl, and Wl of the are pulled out, and one end of the first secondary winding CLI2, one end of the second secondary winding Cw2, and the other end of the first secondary winding CLI2 and the second secondary winding CLI2 are connected to each other. First to third secondary side terminals U2, V2 and W2 are drawn out from the connection point with the other end of the second secondary winding Cw2, respectively.

Also, one end of the first grounding winding Cug and one end of the second grounding winding Cw
One end of the first grounding winding Cug is commonly connected to ground, and the other end of the first grounding winding Cug is connected to the second tap V2t, and the other end of the second grounding winding CWg is connected to the first tap tJ2.
t is connected.

When the present invention is applied to a 400/200 V class distribution transformer, as shown in FIG. Pull out the first and second midpoint terminals from the point.

In addition, when applied to a 400/200 V class distribution transformer, as shown in Figure 8, a curved line protrudes from the midpoint of each of the first secondary winding Cu2 and the second secondary winding CW2. Connect the first and second midpoint terminals in common to this common connection point 0.
is grounded as a neutral point, and the first and second grounding windings Cuc
One end of + and one end of the second ground winding Cwg may be made into idle terminals.

Furthermore, in order to detect the ground fault current, as shown in FIG.
A current transformer CT1 and a second current transformer CT2 for detecting the current flowing through the second ground winding Cwg can be provided.

[Function] In the above configuration, when the common connection point O at one end of the first and second grounding windings Cug and CWg is grounded as shown in FIG. When generating three-phase voltage, the common connection point O of the grounding windings CIJ (+ and CWg) becomes the neutral point.

Therefore, if the secondary circuit is 400V class, the 400V with the middle point grounded by the secondary side terminals U2, V2, and W2
Class 3 phase voltage can be supplied.

Furthermore, when the first and second midpoint terminals are drawn out from the midpoints of the first secondary winding Cu2 and the second secondary winding CW2, as shown in FIG. 5 or FIG. By connecting to the
00/200 V class single-phase three-wire voltage can be supplied to two circuits.

That is, in the case of the connection shown in Fig. 5, the secondary side terminal U
A three-phase 400V class voltage can be supplied from terminals U2, V2, and W2, and a 400/20OV class single-phase three-wire voltage can be supplied from terminals U2, U2n, and W2. Furthermore, a 400/200 V class single-phase three-wire voltage can be supplied to another circuit through terminals V2, V2n, and W2. In this case, the 200V class voltage is 172 which is the 400V class voltage.

In addition, in the case of the connection shown in Fig. 8, terminals IJ2n and ■
2n becomes the common connection point 0 (see Figure 9), and the terminal LJ2
, O, U2e can supply 400/20 OV class single-phase three-wire voltage, and further terminals V2, O.

■2e allows you to supply 400/200 V class single-phase three-wire voltage to another circuit. Also, terminals U2 and V
2.

A 200V class three-phase voltage can be supplied from O, and further a 200V class three-phase voltage can be supplied from terminals U2e, V2e, and O to another circuit. In this case also 200V
The class voltage is 172, which is a 400V class voltage.

In all of the above cases, the neutral point of the 400V class voltage is grounded, so the provisions of Article 23 of the Electrical Equipment Technical Standards can be satisfied.

[Example] The present invention will be described in detail below with reference to the accompanying drawings.

Embodiment 1 FIGS. 1 and 2 show a first embodiment of the present invention. FIG. 1 shows the connections between the windings, and FIG. 2 shows the primary and secondary connections of this embodiment. The following configuration is shown in a vector diagram.

The transformer device of the present invention includes a first unit transformer M1 and a second unit transformer M2. Each unit transformer has iron core I
It is a bare single-phase transformer consisting of a winding C consisting of a primary winding C1, a secondary winding C2, and a grounding winding Cg, and some structural materials for supporting and fixing these. In the embodiment, these unit transformers have an outer iron structure.

Figure 4 is a cross-sectional view showing the right half of the first unit transformer M1 cut along the center plane of the iron core (in this example, it is a wound core), and the left half is symmetrical with respect to the chain line. exhibits a shape. A primary winding C1, a secondary winding C2, and a grounding winding Cg are wound around the central leg of the iron core (1) in this order from the outside. Winding CI
, C2 and C9, and the blank parts outside the winding C1 and inside the winding Cq are insulating parts. The structure of the iron core and winding of the second unit transformer M2 is the same as that of the first unit transformer. First and second unit transformers M1 and M
2 are connected to each other and housed in a common tank (container) Ta as shown in FIG. 3(A) or (B), thereby configuring a three-phase power distribution transformer device.

FIG. 3(A) shows a case where unit transformers M1 and M2 are housed in a tank Ta in a vertically arranged state.
A liquid insulator 1i such as insulating oil is injected into the tank Ta, and a bushing terminal is attached to the upper side of the tank Ta. As will be described later, there are actually multiple bushing terminals [3ul.

Bvl, Bwl, Bo3. Bv2.8w2 etc. are provided, and these bushing terminals are represented by the symbol B in FIG. A gas space Tb is formed in the upper part of the tank, and this gas space is filled with air or nitrogen gas. The upper surface TC of the tank Ta is a cover that can be bent at 22, and is fixed to the upper part of the tank by a tightening device and packing (not shown). Cooling fins or cooling pipes, pole fittings, etc. are attached to the tank Ta as necessary, but these are omitted from the illustration.

FIG. 3(B) shows the first and second unit transformers M1 and M
This figure shows a case in which two tanks 2 are housed in a horizontally arranged state in a tank Ta, and other points are the same as in the case shown in FIG. 3(A).

When configuring a transformer device for mounting on a pole, the structure shown in FIG. 3(A) is suitable from the viewpoint of stability and aesthetics. In addition, when configuring a ground-mounted transformer device, the structure shown in Figure 3 (B) is suitable from the standpoint of stability, but if the floor space is particularly desired to be reduced, the structure shown in Figure 3 (A) is suitable. Sometimes it takes a structure.

Below, the first and second unit transformers M1. The connection between the windings of M2 will be explained with reference to FIG.

Ctll the primary windings of unit transformers M1 and M2, respectively.
(first primary winding) and CWl (second primary winding), and the secondary windings are Cu2 (first secondary winding) and 0, respectively.
w2 (second secondary winding). In addition, the grounding windings of unit transformers M1 and M2 are each CUO (first grounding winding).
and Cwa (second ground winding).

Here, winding Cu1. Cu2. One terminal U of Cug
1゜L12, U (I has the same polarity (therefore, the other terminal U
1e, U2e, and Uge also have the same polarity), and the winding C
WI, CW2゜CW (+ terminal V1, V2
, V(l also has the same polarity (therefore, the other terminals V1e, V2e
, Vae are also of the same polarity). Bul, Bvl, B
wl is the primary bushing terminal, Bo3. By2.8w2
is a secondary bushing terminal, and BO is a grounding bushing terminal.

Here, the number of turns of the primary windings CIJI and CWl is set to be equal, and the number of turns of the secondary windings Cu2 and 0w2 is also set to be equal. The ground windings Cug and Cwg also have the same number of turns.

The connection on the primary side is a normal V connection, and the primary winding CLll
One terminal (first primary terminal) Ul of the primary winding CW1 is connected to the primary bushing 3u1, and one terminal (second primary terminal) Vl of the primary winding CW1 is connected to the primary bushing 3vl. ing. The other terminals U1e and 1 of the primary winding Cul
The other terminal V1e of the secondary winding CW1 is commonly connected, and this common connection point (third primary side terminal) Wl is connected to the primary bushing terminal [3w1].

The ratio of the number of turns between the secondary winding and the ground winding is 3:1. Secondary windings Cu2 and CW2 have taps U2 and V2t, respectively. The number of turns of secondary winding Cu2 and CW2 is N2, the number of turns between terminal U2 and IJ2t and terminal V
The number of turns between 2 and V2 is N2t, and the ground winding Cug and Cw
The number of turns of g is N (represented by l, N2t = (2/3) N2
, N(J = (1/3) N2).

One terminal (first secondary side terminal) U2 of the secondary winding Cu2
is connected to the secondary bushing terminal Bu2, and the secondary winding Cw
One terminal (second secondary side terminal) V2 of 2 is connected to the secondary bushing terminal 3v2. The other terminal U2e of the secondary winding Cu2 and the other terminal v2e of the secondary winding Cw2 are commonly connected, and this common connection point is a third secondary side terminal>
W2 is connected to the secondary bushing terminal BW2.

Also, one terminal U(] of the grounding winding Cuo and the grounding winding Cw
A is commonly connected to one terminal (2) 9, and the common connection point O is connected to the grounding bushing terminal Bo. The grounding bushing terminal Bo is grounded by a grounding wire and maintained at the ground potential.

Tap U2t of secondary winding Cu2 of unit transformer M1 is connected to the other terminal Vge of grounding winding Cwg of unit transformer M2, and tap V2t of secondary winding Cw2 of unit transformer M2 is connected to the other terminal Vge of grounding winding Cwg of unit transformer M2.
is the other terminal Uge of the grounding winding Cug of the unit transformer M1.
It is connected to the.

When connected as described above, the vectors of this embodiment when a three-phase balanced voltage is applied to the primary bushing are as shown in FIG. Here, if the voltage between terminals U2, V2, and W2 is E2, and the ground voltages of terminals U2, V2, and W2 are U3O, V2O, and W2O, respectively, then the magnitudes of U3O, V2O, and W2O are determined from the relationship of the number of turns described above. have an equal phase difference of 120 degrees. U3O, V2O, W2O
(7) Expressing the size as E20, [2=, /1E20
There is r. That is, terminal U2. The neutral point of V2 and Hw2 is O. A portion of the load current also flows through the grounding wire, but if the radial gap between the primary winding and the grounding winding is made sufficiently large as shown in Figure 4, The impedance is much larger than the impedance between the primary and secondary windings. Therefore, the shunt of the load current to the grounded winding is small, but the degree of shunt differs depending on the terminal to which the load is applied. Generally, the ratio of shunt current to the grounding winding with respect to the load between terminals U2 and 2 is the load between terminals V2 and W2 or W2. larger than for the load between U2. Grounding impedance differs depending on the phase, and when the W2 terminal is grounded, when the U2 terminal is grounded, or when the V2 terminal is grounded,
Grounding impedance is smaller than when the terminal is grounded. In this example, the connection on the secondary side is basically a type of connection, but since the neutral point of the electric circuit is grounded,
The secondary circuit can be used for 400v class power distribution.

Embodiment 2 A connection diagram of a second embodiment of the present invention is shown in FIG. 5, and its vector diagram is shown in FIG. 6. This embodiment uses the middle point terminals tJ2n and V from the middle point of the secondary windings Cu2 and 0w2 of the first embodiment.
2n and connected to newly provided secondary bushings 3 u2n and Bv2n, respectively.

The midpoint terminals U2n and V2n extend from a point that equally divides the total number of turns of the windings CIJ2 and CW2, respectively.

To explain the voltage between each terminal on the first unit transformer N1 side, terminal U2. The voltage between U2n is (1/2)E2.
Terminal U2. Since the voltage between U2 is (2/3)E2, the voltage between terminals IJ2t and j12n is (1/6)E2
, the voltage between terminals tJ2n and 0 is (172 points) E2.

The voltage between the midpoint terminal and the terminal at the end of its winding (U2n
, U2 (voltage between J2e, U2n, V2n, V2, and V2e, V2n) is E2h, and the voltage to ground at the midpoint terminal (voltage between U2n, 0 and V2n, 0) is 1.
:2ha, E2h= (1/2)E2 E2ha = (t/24) E2 = 0.2
It becomes a9E2.

Now, assuming that the voltage E2 between the secondary windings is 420 [V],
E20=242[V], E2h=210[V] E
2ho = 121 [V].

In this embodiment, the secondary bushing terminal Bu2. Bv2 and U
Bw2 supplies a three-phase 400V class voltage, and the secondary bushing terminal Bw2. Bu2n and Bu2
It is possible to supply 400/20OV class single-phase three-wire voltage. Also, secondary bushing terminal Bv2. Bv
2n and 8w2 can supply 400/200VI single phase 3 wire voltage.

Example 3 In Example 2, the secondary bushing terminal 3 u2°B
When the three-phase voltage E2 is generated at v2 and 8w2, 2
Next side bushing terminal Bu2n, Bv2n, 8w
A three-phase voltage of E2h-(1/2)E2 is generated between the two.

However, when trying to supply this 3-phase voltage to a load, 2
There is a problem that only half of the next winding (between the terminals LI2e and tJ2n of the winding Cu2 and between the terminals V 2e and V 2h of the winding CW2) can be used.

Also, the ground voltage of the secondary bushing terminal 3w2 is E20=(
1/J) E2, and the secondary bushing Bu2n.

Bv2n, which is the line voltage of 8w2 (1/2)E2
The problem is that it is larger than.

In this embodiment, a connection switching board as shown in FIG. 7 is provided to switch connections, thereby making it possible to supply a three-phase voltage E2h that does not have the above-mentioned problems. In FIG. 7, the inner chain line represents the connection switch panel, and the outer chain line represents the entire transformer device. βq is an external grounding wire connected to the grounding bushing terminal BO;
Although not particularly shown with a symbol in Embodiment 2, the external grounding wire is used in all the embodiments shown in this specification.

A first secondary terminal U2 and a second secondary terminal V2 are drawn out from one end of the secondary windings CL12 and 0w2, respectively.
The connections are the same as in the second embodiment, and the first and second secondary terminals U2 and V2 are connected to bushing terminals Bu2 and Bv2, respectively. Also, in this example, the secondary winding C
The third and fourth secondary terminals U2e and V2e are respectively pulled out from the other ends of u2 and CW2 (the fourth is pulled out and these secondary terminals become bushing terminals 3 u2n and 3v)
Connected to 2n.

The connection switching board has 15 switching terminals D1 to D15 and six switching pieces D21 to D26. The switching terminal D1 is connected to the terminal U2n, and the switching terminal D2 is commonly connected to the terminal D5 and connected to the bushing terminal 3w2. The switching terminal D3 is connected to the terminal V2n, the switching terminals D4 and D6 are connected to the terminals U2e and V2e, respectively, and the switching terminals D7 and D8 are connected to the terminals U(] and Vg, respectively.Switching terminals D9 and [)11 is an idle terminal, and the switching terminal D10 is connected to the bushing terminal Bo. Moreover, the switching terminal D12 is the switching terminal D14.
The switching terminal D13 is connected to the bushing terminal 3v2n together with the switching terminal 015.
2n.

If a connection switching ID as in this embodiment is provided, voltage can be supplied in two ways as shown below by switching the connection piece.

First connection method As shown by the solid line in FIG. 7, the switching terminal DI.

02 and D2 and D3 are connected by switching pieces D21 and D22, respectively, and the switching terminals 04. Between D13 and D6
．． The DIs 2 are connected by switching pieces [) 23 and [) 24, respectively. In addition, switching terminal D7. Between D11 and D8゜D
9 are connected by switching pieces D25 and [)2B, respectively, and bushing terminals Bw2. B
Connect between o and gc with a ground connection line gc.

The connection between the windings when connected in this manner is shown in FIG. 8, and its vector diagram is shown in FIG. 9.

In the case of this first connection method, secondary bushing terminals Bu2. Between BuZn and B v2. A voltage E2 is obtained between B and v2n, respectively. Also, secondary bushing terminal Bu2.8w2. Using Bu2n, bushing terminal B
A single-phase three-wire voltage of voltage E2/E2h can be obtained with w2 as the neutral point. Furthermore, the secondary bushing terminal 3v2.
Using 8w2 and 3v2n, a single-phase three-wire voltage of voltage E2/E2h can be obtained using the bushing terminal 3w2 as a neutral point.

In addition, secondary bushing terminal Bu2. A three-phase voltage E2h can be obtained between Bv2.8w2 and the terminal 3w2 at ground potential, and the secondary bushing terminals BW2.3u2n and B
Three-phase voltage E2h with terminal 3w2 at ground potential between v2n
can be obtained. That is, two single-phase three-wire circuits with voltage E2/E2h and two three-phase circuits with voltage E2h can be obtained simultaneously. In this case, of course, E2h= (1/2
)E2. In this case the ground winding C0 (+ and Cwc
+ is a idle winding with no current, and is connected to the terminal [) on the connection switch board.
11 and D9 are terminals that are simply terminals of one terminal tl and 1 of the grounding windings CLIO and Cwg.

Second Connection Method In the second connection method, the switching terminals D21 and C22 connect switching terminals Di and D15 and D3D14, respectively, as shown by broken lines in FIG.
4 and [) 5 and between [) 6 and [) 5 are connected by switching pieces 1) 23 and [) 24, respectively. Also, switching terminal [)7. [)10 and D8, 010 are connected by switching pieces D25 and C26, respectively. In this case, the ground connection line ZaC is not used.

In this second connection method, the connections between the windings are the same as those shown in FIG. 5, and the supply voltages and vectors are as shown in FIG. 6.

The feature of the third embodiment is that a connection switching board is provided so that the voltage shown in the vector diagram in FIG. 9 can be easily obtained using the switching piece, and the voltage shown in the vector diagram in FIG. 6 can be easily obtained. It is possible to switch to.

Many variations can be envisaged in the arrangement of the bushing terminals and the arrangement of the switching terminals on the connection switching board, with the number of switching terminals and/or switching pieces being greater or less than the example shown in Figure 7. It is also possible to achieve a similar purpose by FIG. 7 shows one example, and the connection switching board is not limited to this.

Embodiment 4 This embodiment uses the first and second current transformers CTI and C70 for detecting the current flowing through the grounding windings Cug and Cva in the first embodiment or the second embodiment as a transformer device. It is built-in. Figure 10 shows the configuration of its main parts.

The first and second current transformers CT1 and C70 are installed in the illustrated polarity, and the first current transformer CT1 uses a current flowing through the terminal Ug as a primary current, and a secondary current proportional to the primary current. occurs. Also, the second current transformer cT2 is connected to the terminal V
The current flowing through g is used as a primary current, and a secondary current proportional to the primary current is generated. A relay circuit block F is provided outside the transformer device and includes three relays R1, R2 and RO, each of which has one end connected in common, and the negative terminal of the secondary circuit of the transformer 3CT1 is connected to the relay R1. connected to the other end. Further, the positive terminal of the secondary circuit of the current transformer CT1 and the negative terminal of the secondary circuit of the current transformer CT2 are connected together to the other end of the relay RO.
The positive terminal of the secondary circuit is connected to the other end of relay R2. Current transformer CT1, C70 and relay R1,
The circuit composed of R2 and Ro is installed at an appropriate location (not shown).

) is grounded.

With this configuration, it is possible to detect a ground fault current in the output circuit of the transformer device. Furthermore, if the ground fault is a ground fault at one end of the line, it is possible to determine whether the line is grounded or not.

Electric currents i1. It is assumed that i2 and 10 are flowing. When load current flows through the secondary winding of a transformer, current flows through the ground winding even when there is no ground fault, but in this case, theoretically 1
1=i2, 1o=Q, and if a ground fault occurs in a part of the secondary winding, grounding winding, and circuits connected to these other than the part where the ground potential is always maintained at zero, then 0.
occurs. In reality, even under normal conditions, a small amount of 10 may flow due to slight imbalances in charging current and leakage current, so 10
A reference value ios is set for ios, and it is determined that a ground fault has occurred when io exceeds this reference value ios.

In the example of Figure 1, assuming that a current transformer is installed as shown in Figure 10, the secondary line (the line connected to the secondary bushing terminal 802.By2゜8w2 in Figure 1) ), consider the case where a ground fault occurs on the negative wire. In this case, when ios≦io and il<<i2, it can be estimated that a ground fault has occurred in the line of the secondary bushing terminal 802. Also, when ios≦10 and i2<<il, it can be estimated that a ground fault has occurred in the line of the secondary bushing terminal BV2, and when ios≦io and 11÷12, it can be estimated that a ground fault has occurred in the line of the secondary bushing terminal BV2.
It can be presumed that a ground condition has occurred in the line of the next bushing terminal Bw2.

In addition, in order to eliminate the influence of the load current shunted to the grounding winding, i
When os≦10, take out the components in phase with 1OS in il, i2 (assumed to be 11° and 12°), and calculate il, i2
Instead of comparing the magnitude of 11°.

By comparing the magnitudes of 2' and making the same determination as above, a more reliable determination of a grounded line can be made.

Other Embodiments In the above embodiments, the first and second unit transformers M1,
Although independent cores were used as the core of M2, the cores of the two unit transformers M1 and M2 were integrated to form the transformer M.
A part of the magnetic path of coils c and c of coils 1 and M2 can also be made common.

For example, when the iron core is integrated based on the structure shown in FIG. 3(A), the lower yoke of the transformer M1 and the upper yoke of the transformer M2 are made common. In this case, if the winding directions of the two coils are reversed, the magnetic flux flowing into the common magnetic path will be transferred to the transformer M1.
, M2 are provided with individual cores, so the cross-sectional area of the common magnetic path portion may be the same as the cross-sectional area of the yoke for one core when transformers M1 and M2 are each provided with separate cores.

In addition, when integrating the core based on the structure shown in Fig. 3 (B), the core is made into a three-legged core structure, with a coil C1C wound around each of the side legs at both ends, and a coil wrapped around the center leg. It has a three-leg iron core two-coil structure with no winding. In this case, if the winding directions of the two coils c and c are opposite to each other, the cross-sectional area of the core of the central leg may be the same as the cross-sectional area of the core of the leg around which the coils are wound.

If the iron core is made into an integral structure in this way, the transformer can be made smaller and lighter.

Further, as opposed to integrating the iron cores of the unit transformers M1 and M2 to unify the configuration as described above, it is also possible to divide the configuration. That is, unit transformers M1 and M2 are housed in separate tanks to constitute two independent unit transformers,
By connecting these externally as shown in FIG. 1 or FIG. 5, the voltage supply described in Embodiment 1 or Embodiment 2 can be performed.

In the above explanation, the voltage E2 between the winding terminals is set to 400
Although the V-class voltage is used, the present invention is not limited to this voltage, and the voltages of each part can be set arbitrarily.

[Effects of the Invention] According to the invention described in claim 1, three-phase voltage is supplied with the common connection point of one end of the first and second grounding windings set as a neutral point and the secondary side grounded. be able to.

Further, according to the invention described in claim 2, the common connection point at one end of the first and second grounding windings is grounded, and the first Since the second neutral point terminal is pulled out, three-phase voltage is supplied with the secondary side neutral point grounded, and the 200 V class voltage is accurately converted to 400 V class voltage 172 to convert the single phase three wire voltage. 2
It has the advantage that it can be supplied to a circuit.

Furthermore, according to the invention described in claim 3, the first and second two
By grounding the first and second midpoint terminals pulled out from the midpoints of the respective windings, the 200■ class voltage can be reduced to 400
There is an advantage that a single-phase three-wire voltage can be supplied to two circuits as a V-class voltage 172, and a three-phase 200V class voltage can be supplied to two circuits.

Further, according to the invention as set forth in claim 4, the ground fault current at the time of a ground fault in the secondary circuit is detected by the two current transformers attached to the current-carrying circuit of the two ground windings, and the ground fault phase is estimated. It can be done easily.

In any of these cases, the neutral point of the three-phase voltage supply circuit can be grounded without increasing the grounding impedance or using an accelerator.
The provisions of Article 1 can be satisfied.

[Brief explanation of the drawing]

Fig. 1 is a connection diagram showing connections between windings in the first embodiment of the present invention, Fig. 2 is a vector diagram showing the relationship between primary and secondary voltages in the embodiment of Fig. 1, and Fig. 3 4 is a schematic configuration diagram showing an example of the mechanical structure of the transformer device of the present invention, and FIG. 4 is a partial cross section showing an example of the cross section of the coil of the transformer device of the present invention and the cross section of the iron core around which the coil is wound. Figure 5 is a connection diagram showing the connection between the windings of the second embodiment of the present invention, Figure 6 is a vector diagram of the secondary voltage of the embodiment of Figure 5, and Figure 7 is the invention A configuration diagram schematically showing the configuration of a connection switching board used in the third embodiment of the present invention, and FIG. 8 is a connection diagram showing the connection between windings in the first connection method of the third embodiment of the present invention. Figure 9 is the 8th
A vector diagram of the secondary voltage of the embodiment shown in the figure, FIG. 10 is a connection diagram showing the main parts of the fourth embodiment of the present invention, and FIGS. 11 to 13 show voltages of various different conventional transformers. A vector diagram showing the relationship, and FIGS. 14 and 15 are connection diagrams showing connections between windings of other conventional transformers, respectively. Ta...tank, ■...iron core, C...winding, B...
...Bushing, Ml...First unit transformer, M2.
...Second unit transformer, C1...Primary winding, C2...
-Secondary winding, CO-...Grounding winding, Bul, 3v1.
3wl/primary bushing, Bo3. By2.8w2.
Bu2n, By2n ・Secondary bushing, BO・
...Grounding bushing, Cu1...first primary winding,
(, wl...second primary winding, Cu2...first two
Secondary winding, 0w2...second secondary winding, Cug...first grounding winding, Cwa...second grounding winding, D...
Connection switching board, D1 to D15...Switching terminal in the connection switching board, [)21 to [)26...Switching piece in the connection switching board, CT1...first current transformer, CT2...first 2
current transformer. Figure 11. Figure 4 Figure Figure Figure Figure 4 Procedural amendment (voluntary) September 18, 1989 Director General of the Japan Patent Office Yoshi 1) Moon Yi 1. Indication of the case Patent application 1982-190295 @ 2. Name of the invention Distribution transformer device 3, relationship with the amended person case Patent applicant (026) Daihen Co., Ltd. 4, agent Akira, 6th floor, Bunzan Building, 4-31-6 Shinbashi, Minato-ku, Tokyo! I
Section I “Detailed Description of the Invention” and Drawings 3 and 15
Figure (1) Correct rNJ on page 9, line 19 to rNej. (2) Correct rNJ to rNeJ in lines 3 and 7 of page 10. (3) Correct "midpoint" in line 15 of page 17 to "neutral point." (4) On page 21, line 4, [22LJ is corrected to “removal”. (5) "1N2" on the 12th line of page 23 is corrected to rNJ, and rIN2tJ on the 13th line of the same page is corrected to r:NtJ. (6) r N2t on page 23, line 15 = (2/3)
N2, Nq = +1/3) N2 J to r N
t − (2/3) N , N (] = (1/3)
Corrected to NJ. (7) Correct “ground wire” in line 4 of page 25 to “ground winding.” (8) Page 26, lines 18 to 20, “E2h,
...If E 2ho,'' is corrected as follows. "Let E2n be the voltage to ground of the midpoint terminal < the voltage between u-2n, o and between V2n and 0) as E2nO tosult." (9
) On page 27, lines 1, 5, and 18, [E2hJ is corrected to I' E 2nJ. (10) rE2hoJ on page 27, lines 2 and 5
Corrected to E2noJ. (11) On page 28, line 6, ``There is a problem that it is large.'' is corrected as follows. [big. Note that E2 /E2n (400/20
Even in the case of single-phase three-wire voltage (class 0), the voltage to ground other than the center terminal is E20, which is higher than E2n of the class 200 voltage. (12) "3-phase voltage E2h" on page 28, line 9 is corrected as follows. "3-phase voltage E2n and single-phase 3-wire voltage E2/E2n"
(13) rE2hj on page 30, line 19 as r E 2nJ
Correct. (14) Page 31, lines 2, 5, 7, and 8. r E 2hJ in the 9th and 10th rows
Correct. (15) Correct "D3" on page 31, line 17 to rD3, J. (16) “One end ground fault” on page 34, line 3 is changed to “-line ground fault”
Correct. (17) “1osJ” on page 35, lines 10-11
Correct to ioJ. (18) On page 35, line 19, [Coils C and C4 are corrected to "iron cores I and H." ■ Figures 3 and 15 of the first drawing are corrected as shown in the attached sheet.

Claims (4)

[Claims] (1) A first primary winding, a first secondary winding, and a first secondary winding.
a first grounding winding having a number of turns that is 1/3 of the total number of turns N of the next winding;
a first unit transformer with a first tap drawn out from the turn point; a second primary winding having the same number of turns as the first primary winding;
a second secondary winding having the same number of turns as the first secondary winding;
The second winding has a number of turns that is 1/3 of the total number of turns N of the second secondary winding.
from one end of the second secondary winding to (2
/3) The second tap is drawn from the point of N turn.
a unit transformer, one end of the first primary winding, one end of the second primary winding;
first to third primary side terminals each drawn out from one end of the secondary winding and the connection point between the other end of the first primary winding and the other end of the second primary winding; Each of the windings was drawn out from one end of the first secondary winding, one end of the second secondary winding, and the connection point between the other end of the first secondary winding and the other end of the second secondary winding. first to third secondary side terminals, one end of the first grounding winding and one end of the second grounding winding are commonly connected and grounded, and the first grounding winding A distribution transformer device characterized in that the other end of the second grounding winding is connected to a second tap, and the other end of the second grounding winding is connected to the first tap. (2) The first and second midpoint terminals are drawn out from midpoints of each of the first secondary winding and the second secondary winding. Distribution transformer equipment. (3) A first primary winding, a first secondary winding, and a first secondary winding.
a first grounding winding having a number of turns that is 1/3 of the total number of turns N of the secondary winding;
) a first unit transformer with a first tap drawn out from the point of N turns; a second primary winding having the same number of turns as the first primary winding;
a second secondary winding having the same number of turns as the first secondary winding;
The second winding has a number of turns that is 1/3 of the total number of turns N of the second secondary winding.
from one end of the second secondary winding to (2
/3) The second tap is drawn from the point of N turn.
a unit transformer, one end of the first primary winding, one end of the second primary winding;
first to third primary side terminals each drawn out from one end of the secondary winding and the connection point between the other end of the first primary winding and the other end of the second primary winding; The first to fourth windings are drawn out from one end of the first secondary winding, one end of the second secondary winding, the other end of the first secondary winding, and the other end of the second secondary winding, respectively. and a secondary terminal of the first secondary winding and the second secondary winding, and the first and second midpoint terminals are drawn out from the midpoints of each of the first and second secondary windings, and both midpoint terminals are connected to each other. The first and second grounding windings are commonly connected and grounded, one end of the first and second grounding windings is an idle terminal, and the other end of the first grounding winding is connected to a second tap, and the second grounding winding is connected to the second tap. A distribution transformer device characterized in that the other end of a grounding winding and a first tap are connected. (4) Claim 1 or 2, further comprising a first current transformer that detects the current flowing through the first grounding winding and a second current transformer that detects the current flowing through the second grounding winding. Distribution transformer equipment as described.