CN111817270A

CN111817270A - Load switch with current anti-interruption function

Info

Publication number: CN111817270A
Application number: CN202010635627.XA
Authority: CN
Inventors: 曹荣杰; 董亚军; 高洁; 李勇跃; 葛谜霞; 杜磊
Original assignee: Henan Huasheng Longyuan Electric Co ltd
Current assignee: Henan Huasheng Longyuan Electric Co ltd
Priority date: 2020-07-03
Filing date: 2020-07-03
Publication date: 2020-10-23

Abstract

The invention relates to a load switch with current anti-interrupt function, comprising a Closing Coil (CC), a Holding Coil (HC), a main rectifier (DX1) for providing direct current for the closing coil, and: the three energy-taking mutual inductors (1CTa, 1CTb and 1CTc) are respectively arranged on the three-phase load switch circuit; the energy-taking transformers (1CTa, 1CTb and 1CTc) are respectively connected with anti-breaking resistors (R2a, R2b and R2c) in parallel; the energy-taking mutual inductors (1CTa, 1CTb and 1CTc) are connected in parallel with a power supply line of the Closing Coil (CC). According to the invention, by utilizing the principle that the current in the load switch circuit is smaller under the normal condition and the current in the load switch circuit is obviously increased under the short-circuit condition, the enough driving current and driving voltage are provided for the closing coil CC under the short-circuit condition through the energy-taking mutual inductor, so that the occurrence of the interruption phenomenon is prevented, the reliability of power supply is ensured, and the separation fault area is searched.

Description

Load switch with current anti-interruption function

Technical Field

The invention relates to the field of load switches, in particular to a load switch with a current interruption prevention function.

Background

A high-voltage load switch is a switch device for breaking a high-voltage line. When a short-circuit fault occurs in a high-voltage line, the line is required to bear short-circuit current in a short time, so that the high-voltage load switch needs to be kept in a closing state.

However, in the case of a short circuit of the high-voltage line, the supply voltage of the high-voltage load switch itself is also lowered, and it is difficult to maintain the closed state. We refer to this phenomenon as the occlusion phenomenon.

Therefore, there is a need for a load switch capable of preventing the occurrence of the interruption phenomenon, ensuring the reliability of the power supply, and searching for the separation failure region.

Disclosure of Invention

The present application is directed to a load switch with a current interruption prevention function, so as to prevent interruption.

In order to achieve the above object, the present invention provides a load switch having a current interruption prevention function,

comprising a Closing Coil (CC), a Holding Coil (HC), a main rectifier (DX1) providing direct current to the closing coil, and:

the three energy-taking mutual inductors (1CTa, 1CTb and 1CTc) are respectively arranged on the three-phase load switch circuit; the energy-taking transformers (1CTa, 1CTb and 1CTc) are respectively connected with anti-breaking resistors (R2a, R2b and R2c) in parallel;

the energy-taking system comprises three energy-taking rectifiers (DX2, DX3 and DX4), wherein the alternating current side of each energy-taking rectifier (DX2, DX3 and DX4) is respectively connected with a corresponding energy-taking transformer (1CTa, 1CTb and 1CTc), and the direct current side of each energy-taking rectifier (DX2, DX3 and DX4) is connected with the direct current side of the main rectifier (DX1) in parallel.

Furthermore, a contact of a contactor (KM) is connected in series on the AC side of the rectifier, and the contact of the contactor (KM) is used for being closed during switching-on and being opened after the switching-on is in place; the Holding Coil (HC), the Closing Coil (CC), the diode (D) and the current limiting resistor (R1) are connected in series to form a holding loop after the closing is in place.

Further, the main rectifier (DX1) is an uncontrolled full bridge rectifier.

Furthermore, each energy-taking rectifier (DX2, DX3 and DX4) is an uncontrolled full-bridge rectifier.

The beneficial effects of the invention are as follows: by utilizing the principle that the current in the load switch circuit is small under the normal condition and the current in the load switch circuit is remarkably increased under the short-circuit condition, the energy-taking mutual inductor is used for providing enough driving current and driving voltage for the closing coil CC under the short-circuit condition, so that the occurrence of the interruption phenomenon is prevented, the reliability of power supply is ensured, and the separation fault area is searched.

Drawings

FIG. 1 is a schematic circuit diagram of one embodiment of a high voltage vacuum load switch with an anti-interrupt function;

in fig. 1, 1 and 2 are 220V ac power supply terminals; 4. 5, 6 are respectively an A-phase current end, a B-phase current end and a C-phase current end, and 7 is a current common end; the signal common terminal is 8, the signal common terminal is 9, and the signal common terminal is 10.

Detailed Description

The following detailed description is made with reference to the accompanying drawings.

A high-voltage vacuum load switch as shown in fig. 1 (the embodiment is described by taking the high-voltage vacuum load switch as an example, and it should be understood by those skilled in the art that the technical solution of the present invention can also be applied to other various types of load switches).

The terminals of the load switch include: 1. 2 is a 220V alternating current power supply end; 4. 5, 6 are respectively an A-phase current end, a B-phase current end and a C-phase current end, and 7 is a current common end; the signal common terminal is 8, the signal common terminal is 9, and the signal common terminal is 10. Wherein, 4, 5, 6, 7 are signal acquisition terminals of current transformers CTa, CTb, CTc inside the load switch, and 8, 9, 10 are status signal acquisition terminals of travel switches CK2-1, CK2-2, which are part of the load switch, but are basically irrelevant to the improvement of the invention, and thus are not described again.

As shown in fig. 1, the improvement of the present embodiment is mainly that energy-taking transformers 1CTa, 1CTb and 1CTc are respectively arranged on a three-phase high-voltage line; by utilizing the principle that the current in the high-voltage line is small under the normal condition and the current in the high-voltage line is remarkably increased under the short-circuit condition, the energy-taking mutual inductors provide enough driving current and driving voltage for the closing coil CC under the short-circuit condition.

Specifically, as the load switch in fig. 1 includes a closing coil CC and a holding coil HC, the improvement is:

on the three-phase high-voltage line, corresponding energy-taking mutual inductors 1CTa, 1CTb and 1CTc are respectively arranged; the energy-taking transformers 1CTa, 1CTb and 1CTc are respectively connected with anti-interrupt resistors R2a, R2b and R2c in parallel;

rectifiers DX2, DX3 and DX4 are respectively arranged, the AC side of each rectifier is respectively connected with corresponding energy-taking transformers 1CTa, 1CTb and 1CTc, and the DC side of each rectifier is connected in parallel with a DC power supply circuit of a closing coil CC.

In addition, the load switch also comprises a rectifier DX1, a contactor KM, a travel switch CK1 and the like; these devices and associated circuitry are well known in the art and are briefly described as follows: the direct current side of the rectifier DX1 is connected with a direct current power supply circuit of a closing coil CC, and the alternating current side of the rectifier is connected with a 220V alternating current power supply through a contact of a contactor KM; the coil of the contactor KM is connected with a travel switch CK1 in series and is connected with a 220V alternating current power supply, when the travel switch CK1 is in place, CK1 is disconnected, the coil of the contactor KM loses power, the contact of the contactor KM is disconnected, the alternating current side of a rectifier DX1 is disconnected, and at the moment, the diode D, the current limiting resistor R1, the holding coil HC and the closing coil CC are connected in series to provide closing holding current for the holding coil HC.

The working principle is as follows:

when the line is normal, a 220V alternating current power supply supplies power to the closing coil CC through the rectifier DX 1.

When the switch is switched on in place, the travel switch CK1 acts, the KM coil loses power, and a 220V alternating current power supply supplies power to the holding coil HC and the switch-on coil CC through the diode D and the resistor R1. At this time, since R1 and the holding coil HC are connected in series, the current at the closing coil CC is small. HC and CC share an iron core, HC can meet the effect of keeping closing under very small current, so that the circuit is prevented from bearing large closing current all the time, and the circuit only needs to bear very small closing keeping current.

Under the normal condition of the circuit, the 1CTa, 1CTb and 1CTc take electricity from a high-voltage line (A, B, C) and provide electricity for a closing coil CC through corresponding rectifiers DX2, DX3 and DX 4. However, at this time, since the current in the high-voltage line is small, the current supplied to the closing coil CC is extremely small.

When a short-circuit fault occurs (single-phase or multi-phase short circuit), the voltage of a 220V alternating-current power supply is remarkably reduced (because the power is also obtained through a high-voltage line), and the driving voltage and the driving current provided for a closing coil CC or a holding coil HC are insufficient; at this time, a large short-circuit current is generated in the high-voltage line, the currents induced by the 1CTa, 1CTb, and 1CTc are significantly increased, and a sufficient driving current can be provided for the closing coil CC, and at the same time, the currents induced by the 1CTa, 1CTb, and 1CTc are converted into voltages through R2a, R2b, and R2c to maintain the driving voltage of the closing line CC.

In the above embodiment, the interruption prevention resistors R2a, R2b, and R2c are equivalent to converting a current source into a voltage source and supplying a driving voltage to the closing coil CC. In addition, the magnitude of the interruption current can be adjusted by changing the resistance value of the interruption-preventing resistor. That is, in order to ensure that the current provided by the energy-taking transformer is small under normal conditions, and the energy-taking transformer can provide enough driving current and driving voltage under short-circuit conditions, an appropriate resistance value (i.e. not too large or too small) should be calculated according to the electrical parameters (such as voltage level, line impedance, etc.) of the application scenario, and those skilled in the art can design and calculate according to the engineering requirements.

Claims

1. A load switch with a current interruption prevention function is characterized in that,

2. The load switch with the current interruption prevention function according to claim 1, wherein a contact of a contactor (KM) is connected in series on the AC side of the rectifier, and the contact of the contactor (KM) is used for being closed when being closed and being opened when being closed; the Holding Coil (HC), the Closing Coil (CC), the diode (D) and the current limiting resistor (R1) are connected in series to form a holding loop after the closing is in place.

3. The load switch with current interrupt prevention function according to claim 2, wherein the main rectifier (DX1) is an uncontrolled full bridge rectifier.

4. The load switch with current interrupt prevention function according to claim 1, wherein each of the energy-extracting rectifiers (DX2, DX3, DX4) is an uncontrolled full-bridge rectifier.