JPH0442898Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a transformer, and more specifically, the present invention relates to a transformer, in which one end of the primary coil of the transformer is connected to one phase of a three-phase alternating current. , a plurality of terminals of the first changeover switch are separately connected and provided at a plurality of locations on the other end side of the primary coil;
This invention relates to a transformer in which a second changeover switch connected to a changeover switch can be freely connected to another phase in a three-phase alternating current or to a neutral point.

[Background of the invention and problems with conventional technology]

First, the background of the invention will be described based on FIG.

Conventionally, a welding machine 3 performs resistance welding such as flash butt welding using the secondary low voltage of a transformer 1.
The voltage between two phases of three-phase AC (for example, 200V) is the primary voltage, and the number of turns is (1/10) to (1/100)
Welding was performed by installing a large number of terminals in a range of degrees and selecting the optimal voltage depending on the material and thickness of the material to be processed.

Generally, electric resistance welding requires a large current, so the secondary coil must be made of two turns of cast copper alloy tube, continuously cooled with cooling water, and must be able to obtain an appropriate voltage. Must be. On the other hand, it is possible to select the number of coil turns on the primary side by moving the contact, but this method is not reproducible and accurate, and inevitably increases the number of terminals, resulting in a large-scale and expensive device. There was an inconvenience.

[Purpose of the invention and its outline]

This invention was made to solve the above-mentioned conventional disadvantages, and the voltage between the end point and neutral point of one phase of three-phase AC is (1/√3) of the voltage between two phases. Utilizing this, a second changeover switch 5 is provided on the primary side of the conventional welding transformer, which can also select a voltage of about 116V, which is (1/√3) of the above-mentioned 200V.

[Example of idea]

FIG. 1 shows a circuit diagram of a transformer 1 as an embodiment of the present invention. One end of the primary coil 7 of the transformer 1 is connected to the end point 9 of the R phase of the three-phase alternating current, and the other end is connected to the first changeover switch 11 with the number of turns (1/10 ) to (1/100) are concatenated separately.

The second changeover switch 5 described above is provided with two terminals 15, one of which is an end point 17 of the S phase.
The other end is connected to the neutral point 23 of the star connection 21 via the terminal 19.

[Effect of idea]

As can be understood from the above explanation, the transformer 1 of the embodiment device of the present invention can lead two types of primary voltages, high and low, of 200V and 116V to both ends of the primary coil 7, as shown in FIG. As shown in Figure 3, even if it has the same number of terminals as the conventional transformer 1 in Figure 3, it has twice the number of stages while keeping the same primary coil 7.
It was possible to choose from 20 different secondary voltages.

In other words, the transformer that embodies the technical idea of the present invention is the second
By simply adding a changeover switch and a connection to the neutral point, the same effect as having twice the number of primary coils was easily obtained.

It is also clear that the design can be easily changed without departing from the technical idea of the present invention.

[Brief explanation of drawings]

Fig. 1 is a wiring diagram of a transformer according to an embodiment of the present invention, Fig. 2 is an explanatory diagram showing an example of the secondary output voltage of the transformer shown in Fig. 1 as a specific voltage, and Fig. 3 is a diagram of a conventional transformer. FIG. 2 is an explanatory diagram showing an example of the secondary side voltage of the device using specific voltages. (Explanation of symbols representing main parts of drawings), 1...
Transformer, 3... Welding machine, 5... Second changeover switch, 11... First changeover switch, 23... Neutral point.

Claims (1)

[Scope of utility model registration request] One end of the primary coil of the transformer is connected to one appropriate phase of the three-phase alternating current, and a plurality of terminals of a first changeover switch are separately connected to multiple locations on the other end of the primary coil. 1. A transformer characterized in that a second changeover switch connected to the first changeover switch is provided so as to be able to connect to another phase of the three-phase alternating current or to a neutral point.