JPS5935164B2 - network transformer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improving the excitation characteristics of a network transformer with a cross-contact prevention plate.

In general, in network power receiving equipment, a network protector installed on the secondary side of a transformer detects power flowing back to the transformer from other parallel lines via the network bus and network protector in case of a fault on the power supply side. A method is adopted in which the protector is made to shatter.

Therefore, the network transformer in this system is required to have sufficient excitation characteristics to cut off the reverse power in the network protector. Conventionally, network transformers have used low-grade silicon steel strips with high loss or thick silicon steel strips with high loss for the cores of network transformers.

However, such iron cores have problems such as the need to prepare a special silicon steel strip for use in the transformer, and the loss of the iron core becomes large and the temperature of the iron core becomes high. These problems become more difficult as the capacity of the transformer increases, or in cases where a high temperature rise cannot be achieved, such as in a molded transformer. The present invention has been made in consideration of the above points, and it is an object of the present invention to provide a network transformer that sufficiently satisfies the required excitation characteristics and can reduce loss without being restricted by the material and dimensions of the iron core. be.

Hereinafter, one embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a cross-sectional view of a winding portion of a conventional transformer with a cross-contact prevention plate, and FIG. 2 is a cross-sectional view of a winding portion of a network transformer with a cross-contact prevention plate according to the present invention. Reference numeral 2 designates a primary winding, 3 a secondary winding, 4 a contact prevention plate, and 5 a winding which also serves as a contact prevention plate and is used to obtain the required excitation characteristics.

As is clear from the figure, the network transformer according to the present invention is provided with a winding 5 that performs the same function and strengthens the excitation of the iron core 1 instead of the conventional contact prevention plate 4. FIG. 3 shows an example of the configuration of this winding 5.
In FIG. 3, 11 and 12 each indicate a winding conductor, which are wound in the same direction. Further, the conductor 12 is wound in n turns, and the conductor 11 is wound in n+l turns, and both conductors 11 and 12 are connected at one end of each winding. In the network transformer according to the present invention configured as described above, when the network transformer is excited, the winding conductor 11,
A voltage corresponding to the difference of one turn is induced between each terminal a and b at the other end of the terminal 12.

When these terminals a and b are short-circuited, a current determined by the voltage for one turn and the resistance and reactance of both conductors 11 and 12 circulates in the winding conductors 11 and 12, and excitation loss and excitation capacity occur. . At this time, stable excitation loss and excitation can be achieved by optimally designing the conductor material, cross-sectional dimensions, and number of turns n for the winding diameter, winding stack, and induced voltage for one turn, which are determined from the network transformer design. capacity can be obtained. In addition, in Fig. 3, the terminals A and b of the winding conductors 11 and 12 may be short-circuited within the winding, and one ground lead wire may be drawn out from this, or the A and b terminals may be connected outside the winding. It may be possible to pull it out so that it can be opened, shorted, and grounded. As described above, the network transformer according to the present invention can easily obtain the required excitation characteristics by providing the winding that also serves as a cross-contact prevention plate between the primary winding and the secondary winding. Furthermore, there are no restrictions on the material of the iron core, the thickness of the steel strip, the designed magnetic flux adhesion, etc. from the excitation characteristics.

In addition, it is possible to easily solve the core cooling problem of molded transformers, etc., where the temperature rise of the core cannot be kept high, eliminating various constraints on transformer design, and making it optimal in terms of cost, size, weight, etc. This has the excellent advantage of enabling the design of network transformers.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a winding portion of a conventional network transformer, FIG. 2 is a sectional view of a winding portion of a network transformer according to an embodiment of the present invention, and FIG. 3 is a sectional view of a winding portion of a network transformer according to an embodiment of the present invention. line 5
FIG. 2 is a side view showing an example of the configuration. 1...Iron core, 2...Primary winding, 3...
...Secondary winding, 4...Touch prevention plate, 5...
... Winding wire, 11, 12 ... Winding conductor.

Claims (1)

[Claims] 1. In transformers with cross-contact prevention plates, network transformers are equipped with windings for excitation loss and excitation capacity generation that also serve as cross-contact prevention plates in order to obtain the excitation characteristics necessary for cutting off reverse power.