CN110853901A

CN110853901A - Short-circuit prevention device of multi-stage voltage output autotransformer

Info

Publication number: CN110853901A
Application number: CN201911163558.0A
Authority: CN
Inventors: 黄欢
Original assignee: Changshu Institute of Technology
Current assignee: Changshu Institute of Technology
Priority date: 2019-11-25
Filing date: 2019-11-25
Publication date: 2020-02-28
Anticipated expiration: 2039-11-25
Also published as: CN110853901B

Abstract

A short-circuit prevention device of a multi-level voltage output autotransformer belongs to the technical field of short-circuit prevention equipment. The relay comprises a first single-pole double-throw relay J1, a second single-pole double-throw relay J2, a third single-pole double-throw relay J3 and a fourth single-pole double-throw relay J4, wherein a movable contact of the first single-pole double-throw relay J1 is connected with a load, a normally closed contact is connected with a first voltage tap T1, a normally open contact is connected with a movable contact of the second single-pole double-throw relay J2, a normally closed contact of the second single-pole double-throw relay J2 is connected with a second voltage tap T2, a normally open contact is connected with a movable contact of the third single-pole double-throw relay J3, a normally closed contact of the third single-pole double-throw relay J3 is connected with a third voltage tap T3, and a normally open contact is connected with a movable contact of the fourth single-pole double-throw relay J36. The advantages are that: the voltage can be safely switched, and the risk of short circuit can be avoided; the problem of power failure at the load end can be avoided, and therefore the generation of induced potential can be eliminated.

Description

Short-circuit prevention device of multi-stage voltage output autotransformer

Technical Field

The invention belongs to the technical field of short-circuit prevention equipment, and particularly relates to a short-circuit prevention device of a multi-stage voltage output autotransformer.

Background

In industrial occasions, an autotransformer is often required to be used for voltage conversion, and the autotransformer generally has a plurality of taps, outputs various voltages through the taps, and supplies the voltages to equipment with different voltage grades on site or adjusts the speed of a motor.

The output of the existing multi-stage autotransformer on the market adopts the technical scheme as shown in figure 1: the rated voltage of AC380V is input, and the output has four taps, can output 30%, 50%, 80% and 100% rated voltage respectively, and four taps are switched through first normally open relay K1, second normally open relay K2, third normally open relay K3 and fourth normally open relay K4. If 30% rated voltage needs to be output, the first normally-open relay K1 is closed, and the second normally-open relay K2, the third normally-open relay K3 and the fourth normally-open relay K4 are disconnected; similarly, if 80% of rated voltage needs to be output, the third normally-open relay K3 is closed, and the first normally-open relay K1, the second normally-open relay K2 and the fourth normally-open relay K4 are disconnected; when the output voltage is not needed, the first normally-open relay K1, the second normally-open relay K2, the third normally-open relay K3 and the fourth normally-open relay K4 are switched off. In the above conventional scheme, when the output voltage needs to be converted, a relay needs to be opened and then closed, for example, when the output voltage is converted from 30% of rated voltage to 80% of rated voltage, the first normally-open relay K1 needs to be opened and then the third normally-open relay K3 needs to be closed, and such an operation may cause the following problems: firstly, if control errors, such as software BUG and the like, can cause the first normally-open relay K1 to be not opened, the third normally-open relay K3 is closed, and when the first normally-open relay K1 and the third normally-open relay K3 are closed simultaneously, the output end of 30% of rated voltage and the output end of 80% of rated voltage of the autotransformer can be directly short-circuited to burn the equipment; secondly, in order to control the problem one, the software potential needs to set a time delay after the first normally open relay K1 is opened, so as to ensure that the normally open relay K1 is opened and then closed, thereby enabling the voltage switching to generate a delay, and further, when the load is of an inductance type, a strong induced potential is generated at the load end to damage the relay.

In view of the above-mentioned prior art, the applicant has made an advantageous design, and the technical solutions described below have been made in this context.

Disclosure of Invention

The invention aims to provide a short-circuit prevention device of a multi-level voltage output autotransformer, which has simple structure and can rapidly switch output voltage,

the object of the present invention is achieved by a short-circuit preventing device for a multi-level voltage output autotransformer, wherein both ends of a primary coil of the multi-level voltage output autotransformer are connected with an input power source, a secondary coil is provided with a first voltage tap T1, a second voltage tap T2, a third voltage tap T3 and a fourth voltage tap T4, and one end of the secondary coil is connected with a load, characterized in that: the short circuit prevention device comprises a first single-pole double-throw relay J1, a second single-pole double-throw relay J2, a third single-pole double-throw relay J3 and a fourth single-pole double-throw relay J4, a movable contact of the first single-pole double-throw relay J1 is connected with a load, a normally closed contact is connected with a first voltage tap T1, a normally open contact is connected with a movable contact of the second single-pole double-throw relay J2, a normally closed contact of the second single-pole double-throw relay J2 is connected with a second voltage tap T2, a normally open contact is connected with a movable contact of the third single-pole double-throw relay J3, a normally closed contact of the third single-pole double-throw relay J3 is connected with a third voltage tap T3, a normally open contact is connected with a movable contact of the fourth single-pole double-throw relay J4, a normally closed contact of the fourth single-pole double-throw relay J4 is connected with a fourth voltage tap T4 and.

The invention adopts a plurality of single-pole double-throw switches to carry out the multi-stage output switching of the autotransformer, and compared with the prior art, the invention has the advantages that: because the single-pole double-throw switch is always broken before closed in space, the situation that any two groups of taps of the autotransformer are not directly connected can be avoided, the voltage can be safely switched, and the risk of short circuit can be avoided; the output can be rapidly switched, the problem of power failure of a load end can be solved, and therefore the generation of induced potential can be eliminated.

Drawings

Fig. 1 is a schematic diagram of the output of a conventional autotransformer.

Fig. 2 is a schematic diagram of the output of the autotransformer of the present invention.

Fig. 3 is a schematic diagram of the autotransformer of the present invention outputting 30% of rated voltage.

Fig. 4 is a schematic diagram of the autotransformer of the present invention outputting 80% of the rated voltage.

Detailed Description

The following detailed description of the embodiments of the present invention will be described with reference to the accompanying drawings, but the description of the embodiments is not intended to limit the technical solutions, and any changes in form and not essential to the inventive concept should be regarded as the protection scope of the present invention.

Referring to fig. 2, the present invention relates to a short-circuit prevention device for a multi-level voltage output autotransformer, wherein two ends of a primary coil of the multi-level voltage output autotransformer are connected to an input power source with a rated voltage of AC380V, and a secondary coil of the multi-level voltage output autotransformer has a first voltage tap T1, a second voltage tap T2, a third voltage tap T3, and a fourth voltage tap T4. In the present embodiment, the first voltage tap T1 is used to output a rated voltage of 30%, the second voltage tap T2 is used to output a rated voltage of 50%, the third voltage tap T3 is used to output a rated voltage of 80%, and the fourth voltage tap T4 is used to output a rated voltage of 100%. One end of the secondary winding is connected to one end of the load, and the other end is a fourth voltage tap T4. Of course, the number of the voltage taps is not limited to four, and the number of the voltage taps can be changed to adjust the output proportion of the rated voltage according to practical application.

The short-circuit prevention device comprises a first single-pole double-throw relay J1, a second single-pole double-throw relay J2, a third single-pole double-throw relay J3 and a fourth single-pole double-throw relay J4. The movable contact of the first single-pole double-throw relay J1 is connected with the other end of the load, the normally closed contact of the first single-pole double-throw relay J1 is connected with a first voltage tap T1, the normally open contact of the first single-pole double-throw relay J2 is connected with the movable contact of the second single-pole double-throw relay J2 is connected with a second voltage tap T2, the normally open contact of the second single-pole double-throw relay J2 is connected with the movable contact of the third single-pole double-throw relay J3, the normally closed contact of the third single-pole double-throw relay J3 is connected with a third voltage tap T3, the normally open contact of the fourth single-pole double-throw relay J4 is connected with the movable contact, the normally closed contact of the fourth single-pole double-throw relay. The four voltage taps are switched by four single-pole double-throw relays.

As shown in fig. 3, when 30% of rated voltage is required to be output, it is only necessary to connect the moving contact of the first single-pole double-throw relay J1 with the normally closed contact, and the moving contact of the second single-pole double-throw relay J2, the moving contact of the third single-pole double-throw relay J3, and the moving contact of the fourth single-pole double-throw relay J4 with the respective normally open contacts.

As shown in fig. 4, when 80% of rated voltage needs to be output, it is only necessary to connect the moving contact of the third single-pole double-throw relay J3 with the normally closed contact, and the moving contact of the first single-pole double-throw relay J1, the moving contact of the second single-pole double-throw relay J2, and the moving contact of the fourth single-pole double-throw relay J4 are connected with the respective normally open contacts.

Under the condition that rated voltage is not required to be output, the movable contact of the first single-pole double-throw relay J1, the movable contact of the second single-pole double-throw relay J2, the movable contact of the third single-pole double-throw relay J3 and the movable contact of the fourth single-pole double-throw relay J4 are respectively connected with respective normally open contacts.

The invention adopts a cascade circuit of a plurality of single-pole double-throw switches, and the single-pole double-throw switches are used for carrying out multi-stage output switching of the autotransformer. Because the single-pole double-throw switch is always broken before closed in space, the situation that any two groups of taps of the autotransformer are not directly connected can be avoided, the voltage can be safely switched, and the risk of short circuit is avoided. Further, since the output can be switched rapidly, the problem of power failure at the load end can be ensured, and the generation of induced potential can be eliminated.

Claims

1. A short-circuit prevention apparatus for a multi-level voltage output autotransformer having a primary winding connected across an input power source, a secondary winding having a first voltage tap T1, a second voltage tap T2, a third voltage tap T3, and a fourth voltage tap T4, the secondary winding having a load connected at one end thereof, the apparatus comprising: the short circuit prevention device comprises a first single-pole double-throw relay J1, a second single-pole double-throw relay J2, a third single-pole double-throw relay J3 and a fourth single-pole double-throw relay J4, a movable contact of the first single-pole double-throw relay J1 is connected with a load, a normally closed contact is connected with a first voltage tap T1, a normally open contact is connected with a movable contact of the second single-pole double-throw relay J2, a normally closed contact of the second single-pole double-throw relay J2 is connected with a second voltage tap T2, a normally open contact is connected with a movable contact of the third single-pole double-throw relay J3, a normally closed contact of the third single-pole double-throw relay J3 is connected with a third voltage tap T3, a normally open contact is connected with a movable contact of the fourth single-pole double-throw relay J4, a normally closed contact of the fourth single-pole double-throw relay J4 is connected with a fourth voltage tap T4 and.