Split-phase isolation protection device for secondary circuit of voltage transformer

Abstract

A split-phase isolation protection device for a secondary circuit of a voltage transformer comprises a plurality of junction boxes and a PT terminal box, an original air switch is arranged in the PT terminal box, an active drive-by-wire air switch is arranged in the junction box, an operation indication module is arranged in the PT terminal box, and the original air switch and the active drive-by-wire air switch are both connected with the operation indication module; the technical problem to be solved by the utility model is to provide the split-phase isolation protection device for the secondary circuit of the voltage transformer, and the short-circuit fault of the split-phase secondary circuit between the secondary junction box of the voltage transformer body and the PT terminal box can be effectively protected through the split-phase isolation protection device. And meanwhile, the PT terminal box can be used for air switch control and state monitoring of the secondary junction box of each split-phase body, so that secondary circuit isolation during maintenance or defect treatment is facilitated.

Description

Technical Field

[0001] The utility model relates to the technical field of instrument transformers, in particular to a phase-separated isolation protection device for the secondary circuit of a voltage transformer. Background Art

[0002] Voltage transformers (referred to as PTs) are widely used in power systems. Since a short circuit on the secondary side of a voltage transformer can cause equipment burnout, air switches or fuses are usually installed in the secondary circuit of the voltage transformer to play a protective role.

[0003] In a high-voltage power grid, voltage transformers are arranged separately for each phase. There is usually a certain distance between the three transformers of phases A, B, and C, as Figure 1 shown. For the convenience of wiring secondary equipment, the existing method is as follows: The secondary body coils of phases A, B, and C of the voltage transformer are led out to the respective phase connection boxes. The secondary circuits of the three phases are separately led from the connection boxes to the PT terminal box through separate secondary cables. In the PT terminal box, through a centrally arranged air switch or fuse, and then sent out through the secondary cable to be collected and used by secondary equipment such as protection and measuring instruments, as Figure 2 shown.

[0004] The existing technology has the following deficiencies:

[0005] 1) When a short circuit occurs between a section of cable connecting the phase-separated connection box of the voltage transformer and the PT terminal box, since the fault point is before the air switch in the PT terminal box, the air switch in the PT terminal box cannot play a protective role, the fault cannot be removed, the secondary side of the voltage transformer will always be in a short-circuit state, which will cause the voltage transformer to burn out and be damaged, and the power station equipment will be forced to stop operating, resulting in economic losses.

[0006] 2) For voltage transformers of 220 kV and above, according to the requirements of live working safety distances, the connection box is generally very high from the ground. Maintenance personnel cannot open the connection box for observation and operation without using a ladder or a work vehicle. If an ordinary air switch is installed in the connection box, once the air switch in the connection box fails or trips for other reasons during the live operation of the voltage transformer, maintenance personnel cannot directly check and operate on the ground. To open the connection box involves working at height, and safety distances and the risk of electric shock to personnel need to be considered. Summary of the Invention

[0007] The technical problem to be solved by the utility model is to provide a phase-separated isolation protection device for the secondary circuit of a voltage transformer. Through this device, the short-circuit faults of the phase-separated secondary circuits between the secondary connection box of the voltage transformer body and the PT terminal box can be effectively protected. At the same time, in the PT terminal box, the air switches of each phase-separated body secondary connection box can be controlled and the status can be monitored, which is convenient for the isolation of the secondary circuit during maintenance or defect handling.

[0008] To solve the above technical problems, the technical solution adopted by the present utility model is as follows: A phase-separated isolation protection device for the secondary circuit of a voltage transformer, comprising a plurality of junction boxes and a PT terminal box. An original air switch is provided in the PT terminal box, an active line-controlled air switch is provided in the junction box, and an operation indication module is provided in the PT terminal box. The original air switch and the active line-controlled air switch are both connected to the operation indication module;

[0009] The operation indication module includes a power supply terminal and a plurality of wiring units. Each wiring unit includes an active line-controlled air switch terminal for connecting to the active line-controlled air switch and an original air switch terminal for connecting to the original air switch;

[0010] There are three active line-controlled air switch terminals. One terminal is connected to the positive pole of the power supply, and the other two terminals are connected to the negative pole of the power supply;

[0011] There are three original air switch terminals. One terminal is connected to the positive pole of the power supply, then divides into two paths and is respectively connected to the trip button and the close button, and then connected to the other two terminals. The other two terminals are used to connect to the original air switch, and the original air switch is then connected to the negative pole of the power supply.

[0012] Preferably, the two terminals of the active line-controlled air switch terminal connected to the negative pole of the power supply are respectively connected to the trip LED indicator and the close LED indicator, and then connected to the negative pole of the power supply.

[0013] Preferably, an indicating power supply knob switch is provided on the power supply circuit of the active line-controlled air switch terminal.

[0014] Preferably, an operating power supply knob switch is provided on the power supply circuit of the original air switch terminal.

[0015] The present utility model provides a phase-separated isolation protection device for the secondary circuit of a voltage transformer, having the following beneficial effects:

[0016] Advantage 1: Eliminate the protection dead zone and avoid damage to the voltage transformer equipment.

[0017] When the cable insulation between the voltage transformer junction box and the PT terminal box is damaged or the wiring is incorrect, resulting in a short circuit, the air switch in the transformer junction box trips, isolating the fault point from the voltage transformer body, and avoiding the voltage transformer from being burned due to a secondary side short circuit.

[0018] Advantage 2: Can manually control the phase-separated air switch isolation centrally to avoid power outage of the voltage transformer.

[0019] When dealing with defects in the secondary voltage circuit during operation, relying on this system, the operator can manually operate the air switch in the ground PT terminal box to disconnect the power supply of the phase-separated junction box, so that the circuit between the junction box and the PT terminal box is de-energized. Defect handling on this section of the secondary circuit no longer requires the power outage of the voltage transformer equipment.

[0020] Advantage 3: High system self-safety.

[0021] Adopting the active control method of cables, the control power supply can be disconnected during normal operation, effectively ensuring reliability under strong electromagnetic interference and preventing the air switch from being misoperated due to control reasons.

[0022] Advantage 4: High work efficiency.

[0023] When the voltage transformer is out of service for maintenance, it is necessary to check the insulation of the lead wires from the transformer body and the secondary circuit as a regular maintenance item. In the past, to distinguish the insulation between the lead wires from the transformer body and the secondary cables from the phase-separated junction box to the PT terminal box, it was only possible to climb high to open the phase-separated junction box and remove the secondary wiring to check their insulation separately. After installing the system proposed by the present invention on the secondary side of the voltage transformer, the secondary lead wires of the transformer in the phase-separated junction box can be isolated phase by phase directly through this system at the PT terminal on the ground, greatly improving the work efficiency. Description of the Drawings

[0024] The following further describes the present utility model in conjunction with the drawings and embodiments:

[0025] Figure 1 is the layout diagram of the existing voltage transformer;

[0026] Figure 2 is the schematic diagram of the secondary wiring relationship of the existing voltage transformer;

[0027] Figure 3 is the structural schematic diagram of the present utility model;

[0028] Figure 4 is the structural schematic diagram of the operation indication module of the present utility model;

[0029] Figure 5 is the internal wiring schematic diagram of the operation indication module of the present utility model;

[0030] Figure 6 is the structural schematic diagram of the air switch of the present utility model. Detailed Embodiment

[0031] Such as Figures 3-5As shown in the figure, a phase-separated isolation protection device for the secondary circuit of a voltage transformer includes a number of junction boxes 1 and a PT terminal box 2. An original air switch 3 is provided in the PT terminal box 2, an active line-controlled air switch 4 is provided in the junction box 1, and an operation indication module 5 is provided in the PT terminal box 2. The original air switch 3 and the active line-controlled air switch 4 are both connected to the operation indication module 5;

[0032] The operation indication module 5 includes a power supply terminal 6 and a number of wiring units 7. Each wiring unit includes an active line-controlled air switch terminal 8 for connecting to the active line-controlled air switch 4 and an original air switch terminal 9 for connecting to the original air switch 3;

[0033] There are three active line-controlled air switch terminals 8. One terminal is connected to the positive pole of the power supply, and the other two terminals are connected to the negative pole of the power supply;

[0034] There are three original air switch terminals 9. One terminal is connected to the positive pole of the power supply, then divides into two paths and is respectively connected to the trip button 10 and the close button 11 and then connected to the other two terminals. The other two terminals are used to connect to the original air switch 3, and the original air switch 3 is then connected to the negative pole of the power supply.

[0035] Preferably, the two terminals of the active line-controlled air switch terminal 8 connected to the negative pole of the power supply are respectively connected to the trip LED indicator 12 and the close LED indicator 13 and then connected to the negative pole of the power supply.

[0036] Preferably, an indication power supply knob switch 14 is provided on the power supply circuit of the active line-controlled air switch terminal 8.

[0037] Preferably, an operation power supply knob switch 15 is provided on the power supply circuit of the original air switch terminal 9.

[0038] Preferably, there are three dry junction boxes 1 and three wiring units 7 for three-phase wiring. This device can flexibly adjust the number of phases used.

[0039] Specifically, the operation instruction module is provided with 2 power supply switching-off switches, which are respectively used to control the operation power supply and the indication power supply. The operation instruction module is provided with operation buttons for controlling the opening and closing of the air switches in the A, B, and C phase junction boxes. The buttons are marked with A, B, and C phases to distinguish the phase types, with red indicating closing and green indicating opening. The operation instruction module is provided with 6 indicator lights, and when lit, they respectively indicate that the air switches of the A, B, and C phases are in the closed or open state. The operation instruction module is provided with 20 terminal blocks. Among them, the 2 upper left terminal blocks are externally connected to the working power supply for the operation power supply and the indication power supply; the 9 upper terminal blocks are divided into three groups to connect to the closing and opening states of the air switches in the A, B, and C phase junction boxes for indication; the 9 lower terminal blocks are divided into three groups to connect to the opening and closing operations of the air switches in the A, B, and C phase junction boxes. The operation instruction module is installed in the PT terminal box, and its size is the same as that of a 4-bit air switch and can be fixed on the card slot of the air switch guide rail.

[0040] There are a total of 3 groups of secondary cables, which are respectively connected to the operation instruction module in the PT terminal box and the active line-controlled air switches and their auxiliary contacts in the A, B, and C phase junction boxes.

[0041] The air switch is as Figure 6 shown. In addition to having the protection function of a common air switch, this air switch can also be remotely controlled to open and close through external power supply wiring. It is connected to the operation instruction module through a secondary cable and receives its opening and closing instructions. The active line-controlled air switch is installed in the A, B, and C phase junction boxes, and the supporting auxiliary contacts provide its opening and closing states to the operation instruction module in the PT terminal box.

[0042] The working principle of this device is as follows:

[0043] 1) During normal operation, the active line-controlled air switches in the system are all closed, the closing states of the auxiliary contacts are connected, and the closing state indicator lights of the A, B, and C phases on the operation instruction module in the PT terminal box are on, while the opening state lights are off.

[0044] 2) At a certain moment, a fault occurs in the secondary circuit between the voltage transformer junction box and the PT terminal box. The active line-controlled air switch will automatically trip to cut off the fault. When the operation and maintenance personnel go to the site for inspection, they can observe the A, B, and C phase indicator lights on the operation instruction module in the PT terminal box. Assuming that the fault occurs in phase A, the closing state light of phase A is off, the opening state light is on, the state lights of phases B and C are on, and the opening state lights are off. The operation and maintenance personnel can judge that the air switch in the phase A junction box of the voltage transformer has tripped.

[0045] 3) After the fault location is processed, when it is necessary to restore power to the secondary circuit of the voltage transformer, the operation and maintenance personnel press the closing button of phase A on the operation instruction module in the PT terminal box. After the active line-controlled air switch in the phase A junction box receives the closing command and closes normally, the closing state indicator light on the operation instruction module of phase A is on, and the opening state light is off.

[0046] The above embodiments are only the preferred technical solutions of the present utility model and should not be regarded as limitations on the present utility model. The protection scope of the present utility model shall be the technical solutions recited in the claims, including equivalent replacement solutions of the technical features in the technical solutions recited in the claims. That is, equivalent replacement improvements within this scope are also within the protection scope of the present utility model.

Claims

1. A phase-separated isolation protection device for the secondary circuit of a voltage transformer, comprising a plurality of junction boxes (1) and a PT terminal box (2), and an original air switch (3) is provided in the PT terminal box (2), characterized in that: An active line-controlled air switch (4) is provided inside the junction box (1), and an operation indication module (5) is provided inside the PT terminal box (2). The original air switch (3) and the active line-controlled air switch (4) are both connected to the operation indication module (5). The operation indication module (5) includes a power supply terminal (6) and a number of wiring units (7). Each wiring unit includes an active line-controlled air switch terminal (8) for connecting to the active line-controlled air switch (4) and an original air switch terminal (9) for connecting to the original air switch (3). There are three active line-controlled air switch terminals (8). One of the terminals is connected to the positive power supply, and the other two terminals are connected to the negative power supply. There are three original air switch terminals (9). One of the terminals is connected to the positive power supply, then divides into two paths and is respectively connected to the tripping button (10) and the closing button (11) and then connected to the other two terminals. The other two terminals are used to connect to the original air switch (3), and the original air switch (3) is then connected to the negative power supply.

2. The phase-separated isolation protection device for the secondary circuit of a voltage transformer according to claim 1, characterized in that: The two terminals of the active line-controlled air switch terminal (8) that are connected to the negative power supply are respectively connected to the tripping LED indicator (12) and the closing LED indicator (13) and then connected to the negative power supply.

3. The phase-separated isolation protection device for the secondary circuit of a voltage transformer according to claim 2, wherein: An indication power supply knob switch (14) is provided on the power supply circuit of the active line-controlled air switch terminal (8).

4. The phase-separated isolation protection device for the secondary circuit of a voltage transformer according to claim 2, wherein: An operation power supply knob switch (15) is provided on the power supply circuit of the original air switch terminal (9).

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