JPS6130254Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a multiphase transformer in which an excessive transient current flows in a particular phase.

For example, when the load 2 of a three-phase transformer 1 includes a capacitor 3 in one phase as in the system shown in FIG.
A transient charging current flows. As a result, when the capacitance of the capacitor 3 is large, the electromagnetic force generated by the transient charging current becomes large, and the transformer winding 5 of the phase corresponding to the load phase to which the capacitor 3 is connected (see Fig. (W-phase winding) may vibrate due to this electromagnetic force.

Figure 2 shows a case where the three-phase transformer is a power transformer for a low-frequency induction furnace. In the figure, 6 and 7 are a balancing reactor and a balancing capacitor, respectively, and both A balancing device is configured. 8 is an induction furnace and 9 is a capacitor for improving the power factor. In this system, a balancing capacitor 7 is connected to the load phase other than the W phase (U phase in the figure), but normally the capacitance of this capacitor 7 is small, compared to that of the power factor correction capacitor 9. Since the capacity is much larger, when the switch 4 is closed, the transformer winding 5 (W-phase winding) corresponding to the load phase including the power factor correction capacitor 9 is connected, as in the case of Fig. 1.
There is a risk that the transformer winding 5d (U phase in the figure), which corresponds to the load phase of the balancing capacitor 7, may receive a larger electromagnetic force and vibrate.

Therefore, in the systems shown in Figures 1 and 2, if the capacitances of capacitors 3 and 9 are large and their transient charging current produces the electromagnetic force as described above,
Since a conventional three-phase transformer has the same winding configuration for each phase winding, while the switch 4 is repeatedly opened and closed over a long period of time, only the insulation covering of the W-phase winding conductor is removed. However, it is damaged due to mechanical vibration, which eventually leads to insulation breakdown and shortens the life of the transformer.In order to prevent this, each phase must be made more robust than necessary, so it is necessary to increase the size and height of the transformer. It had some drawbacks when it came to price.

This idea was made in order to eliminate the above-mentioned drawbacks, and the winding configuration of the phase that receives stronger electromagnetic force than other phases due to large transient currents is designed to be more resistant to electromagnetic vibration than the other phases. It is an object of the present invention to provide an inexpensive polyphase winding that can bear a load through which an unbalanced transient current flows without reducing the life of the transformer by changing the winding configuration.

This invention will be described below with reference to examples.

Embodiment 1 A transformer winding through which a large transient current flows compared to other phases when switching a load, for example, the W-phase winding of the three-phase transformer 1 in FIGS. 1 and 2 (low-voltage side winding and high-voltage side winding) The varnish is used to firmly fix the low-voltage and high-voltage windings and the strands to each other using the varnish. In the winding constructed in this manner, even if the electromagnetic force described above is repeatedly applied, no relative movement occurs between the windings and between the strands, so that the insulating covering, such as the insulating paper of the paper-wrapped electric wire, is not damaged.

Embodiment 2 The diameter of the strands constituting the W-phase winding of the three-phase transformer 1 is made larger than the diameters of the strands of the U-phase and V-phase windings.
Since the W-phase winding constructed in this way is heavier than the other phase windings, even when subjected to the above electromagnetic force, the relative vibrations between the windings and between the strands will not correspond to the increase in weight. damage to the insulation sheathing is reduced accordingly.

Embodiment 3 The thickness of the insulation covering of the strands constituting the W-phase winding of the three-phase transformer 1 is made thicker than that of the other phase windings (U-phase and V-phase windings). As a result, the life of the insulating sheath of the W-phase winding can be extended compared to the conventional case.

Note that similar effects can be obtained whether the three-phase transformer 1 is a single-phase transformer or a multi-phase transformer.

As described above, according to this invention, when a load is applied, electromagnetic vibration resistance treatment is applied only to the transformer winding of the phase in which a large transient current flows among the windings of each phase. To provide an inexpensive multi-phase transformer capable of carrying a load in which a large unbalanced transient current flows each time the power is turned on, without accelerating the insulation deterioration of the transformer windings and shortening the life of the transformer. It can be produced without significantly increasing the physique.

[Brief explanation of the drawing]

1 and 2 are connection diagrams of a three-phase transformer and a load circuit. In the figure, 5 is a transformer winding. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims for Utility Model Registration] (1) In a product having multi-phase windings, electromagnetic vibration resistance treatment is applied only to the windings of the phases in which a large transient current flows among the above-mentioned phase windings, and the windings of other phases are A polyphase transformer characterized by having different configurations. (2) The polyphase transformer according to claim 1, wherein the anti-electromagnetic vibration treatment is an increase in the weight of the transformer winding. (3) The polyphase transformer according to claim 1, wherein the anti-electromagnetic vibration treatment is a treatment for fixing the low-voltage and high-voltage side windings to each other and the strands to each other. (4) The polyphase transformer according to claim 1, wherein the anti-electromagnetic vibration treatment is an increase in the thickness of the strand insulation covering of the transformer winding.