JPH01295619A - Abnormal state monitor for on-load tap changer - Google Patents

Abstract

PURPOSE:To always monitor an abnormal state by detecting current flowing through a change-over switch, with an optical CT, to conduct the current with an optical cable for photoelectric conversion, at the time of the tap change-over of a transformer under working, and by finding a change-over time and the scale of the flowing current. CONSTITUTION:The tap of a voltage change-over switch 2 in an oil tank 1 its selected by a selector 3, and the output voltage of a transformer under working is regulated. In its case, under change-over operation, current flowing to a conductor 4 for connecting the change-over switch 2 and the tap of the selector 3 to each other is detected by an optical CT 12 fitted in insulation oil, and is transmitted to an optical cable 13, and the input to a photoelectric converter 14 outside the oil tank is provided. The input of electric signal from the photoelectric converter 14, to a monitor 14a is provided, and the scale of current and a tap change-over time are measured, and the existence of an abnormal state is discriminated. If the abnormal state exists, alarm is generated and operation is stopped. As a result, a working state is always monitored, and the abnormal state is found earlier, and the damage of an equipment due to the abnormal state is limited to a minimum.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an abnormality monitoring device for an on-load tap changer that switches the taps of a transformer under load without disconnecting it from the line.

[Conventional technology]

Generally, the on-load tap changer of a transformer is an embedded type that is housed in the transformer tank, and is broadly divided into a switching switch and a tap selector. Figure 4 is an external view of an on-load tap changer and a conventional abnormality monitoring device, in which (1) is the transformer tank containing insulating oil (not shown), and (2) is the tank that has been contaminated by the arc generated during switching. The switching switch (3) has an oil-tight structure to prevent the insulating oil (not shown) from mixing with the insulating oil in the transformer tank (1). Okarekatsu switching switch (
2) K-connected tap selector, (4) is a conductor that connects the switching switch (2) and tap selector (3) and supplies electricity, and (5) is a conductor whose volume of insulating oil changes due to temperature changes. A conservator (6) is provided to ensure that the changeover switch (2) is always filled with sufficient insulating oil.
5) and the switching switch (2), and pipe (7) is installed in the conservator (5) to discharge the gas when the insulating oil is gasified during switching. Vent,
(8) is a protective relay as an abnormality monitoring device installed in the middle of the pipe (6) to detect the amount of gas; (9)
is a pressure relief plate that is destroyed when the pressure inside the switching switch (2) rapidly increases due to a switching abnormality, thereby preventing damage to the switching switching chamber.

Figure 5 shows a cross-sectional view of the switching switch (2), where (15) is the contact, (16) is the rotation axis of the contact (15), which has a three-pole configuration, and (1'7) is the contact ( 1
5) is a current limiting resistor that limits the current flow.

Figure 6 is a connection diagram of the on-load tap changer and transformer, where (19) is the fixed contact of the tap selector (3), (20)
are movable contacts (21) that contact these fixed contacts (19);
) is the transformer winding.

Next, the operation will be explained. 1. For example, consider a case where an odd tap is switched to an even tap during a load operation. Figure 6 For example, terminals 3 and 4 of the tap selector (3)
The #r terminal is selected and normal operation is performed with the 3rd terminal. When attempting to switch from this state to the No. 4 terminal, the switching is completed through the processes from (a) to (g) in FIG.

During this process, the contacts open and close, creating an arc. In particular, when both the contacts of the odd-numbered taps and the even-numbered taps are closed, the taps are short-circuited by the current limiting resistor (18), and a large arc is likely to occur. FIG. 5 shows the above-mentioned arc generation mechanism. The arc generated in this way vaporizes the insulating oil in the switch (2) and generates gas. (6), conservator (5) K reservoir, and is discharged from the discharge port (7). The amount of gas generated is determined by the protection relay (8) installed on the pipe.
It is being monitored by K. If abnormal switching occurs, such as overcurrent switching, damage to contactor (15), current limiting resistor (18),
), a delay in the switching time, etc., a large amount of gas will be generated and the protection relay (8) will activate and issue an alarm. If this alarm is issued, it is necessary to immediately stop the operation of the transformer and inspect the switching switch (2).

[Problem to be solved by the invention]

Conventional monitoring devices for on-load tap changers
The on-load tap changer was left unattended until the 7 relays were activated, and by the time the protective relay was activated and an abnormality was discovered, the on-load tap changer had already been damaged and the transformer was also damaged. There were problems such as the possibility of giving.

This invention was made in order to solve the above-mentioned problems, and it is possible to detect abnormalities in the switching switch of the on-load tap changer at an early stage and minimize damage. The purpose is to obtain a monitoring device.

[Means for solving problems]

The on-load tap changer abnormality monitoring device according to the present invention includes:
An optical CT that constantly detects the current of the switching switch, a photoconductor that guides its output signal to the outside of the transformer, a photoelectric conversion device that converts the guided optical signal into an electrical signal, and a photoelectric conversion device that receives and processes the signal.・It is equipped with a monitoring device for making judgments.

[For production]

In this invention, the current of the switching switch is constantly detected by optical CT, and its output is guided as an optical signal to the outside of the transformer tank by an optical fiber, allowing for the most stable detection. Furthermore, since the optical fiber is an insulator, the structure can be simplified regardless of the operating voltage of the on-load tap changer.

〔Example〕

FIG. 1 is an external view showing an embodiment of the present invention.
) to (9) are exactly the same as those in the conventional device. (12) is the switching switch (2) and the tap selector (3).
) is installed on the conductor (4) connecting the switch (
2) Optical CT for detecting current, (13) Optical CT
(12) is a photoconductor, such as an optical fiber, that transmits the optical signal output from the transformer tank (1) to the outside; (14) is a photoelectric conversion device that converts the optical signal received from the optical fiber (13) into an electrical signal; (14a) is a photoelectric conversion device (14
) This is a monitoring device that measures the magnitude of the current flowing through the switching switch (2) k, the tap switching time, etc. from the electrical signal received from the switching switch (2), and determines whether the tap changer is abnormal or normal under load. Fig. 2 shows a connection diagram of a load tap changer and a transformer equipped with the abnormality monitoring device of the present invention, and Fig. 6, which shows a conventional device, shows an optical CT (12), an optical fiber (13), and a photoelectric conversion device. (14) and a monitor (14a) are added.

Next, the operation of the above embodiment will be explained with reference to FIG. The operation mechanism of the switching switch (2) of the on-load tap changer is completely the same as that of the conventional device, that is, the explanation of FIGS. 4 to 7, and will not be described here.

The current flowing through the switching switch (2) is constantly detected by an optical CT (12)K provided with a conductor (4)K, and its output optical signal is sent to a photoelectric conversion device (1) via an optical fiber (13)K.
4), where it is converted into an electrical signal again, and the output is inputted into the monitor (14a) K, where it is connected to the switching switch (14a).
Measure and judge whether the current value in step 2) is within the rated value and whether the switching time is within the rated time. If the current value is above the rated value, an alarm signal is output from the monitor k (14a) and the transformation is stopped. Shut down the equipment.

On the other hand, if the value is within the rated value, operation will continue and monitoring will continue. The above explanation is shown in the form of a flowchart in the third section.
It is a diagram.

In addition, in the abnormality monitoring system ft of this invention, since the switching current and switching time of the switching switch are constantly measured, the amount of wear of the contacts of the switching switch can be estimated and the switching opening/closing can be performed from the switching current value and switching time. It is possible to estimate the contamination of the insulating oil in the chamber, and it is possible to instruct the timing of contact inspection and replacement, as well as the time of replacing the insulating oil, from the abnormality monitoring device. In addition, since the current is measured even when the tap is in the fixed position, if the rated current of the switching switch is exceeded, the abnormality monitoring device will issue a signal to block the tap switching command, preventing damage due to overcurrent switching. can do.

〔Effect of the invention〕

As described above, the present invention provides an optical CT that detects iER flowing through a switching switch at the time of tap switching, a photoconductor that conducts an optical signal output from the optical CT, and a signal that is guided by the photoconductor. a photoelectric conversion device that converts an optical signal into an electrical signal; and a photoelectric conversion device that receives the electrical signal from the photoelectric conversion device, measures the magnitude of the current flowing through the switching switch, the tap switching time, etc., and measures the tap switching time, etc. Since it is equipped with a monitor that determines whether the tap changer is abnormal or normal, the current flowing through the switching switch of the tap changer during load can be constantly monitored. This has the effect of minimizing damage to the equipment.

[Brief explanation of the drawing]

Fig. 1 is an external view showing an embodiment of the present invention, Fig. 2 is a connection diagram of a tap changer and transformer equipped with the abnormality monitoring device of the present invention, and Fig. 3 is a diagram of the connection of a tap changer and a transformer equipped with the abnormality monitoring device of the present invention. Flow chart diagram, Fig. 4 is an external view of a tap changer on load with a conventional abnormality monitoring device, Fig. 5 is a sectional view of the switching switch shown in Fig. 4, and Fig. 6 is a diagram of a tap changer on load with a conventional abnormality monitoring device. This wiring diagram of the transformer, FIG. 7, is a switching sequence diagram of the on-load tap changer. In the figure, (1) is the transformer tank, (2) is the switching switch, (3) is the tap selector, (12) is the optical CT, (13) is the
) is a photoconductor, (14) is a photoelectric conversion device, and (14a) is a monitor. In addition, in the figures, the same reference numerals indicate the same or corresponding parts. Shape 1 Figure 1: 9fiR9:, t7 14:
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Claims (1)

[Claims] In an abnormality monitoring device for an on-load tap changer that is housed in a transformer tank, has a changeover switch and a tap selector, and adjusts voltage during load operation, detects the current flowing through the changeover switch when a tap is changed. This light CT and this light C
A photoconductor that transmits the optical signal output from T, a photoelectric conversion device that converts the optical signal guided by the photoconductor into an electrical signal, and a photoelectric conversion device that receives the electrical signal from the photoelectric conversion device, Abnormality monitoring of an on-load tap changer, characterized by comprising a monitor that measures the magnitude of the current flowing through the switching switch, the tap switching time, etc., and determines whether the on-load tap changer is abnormal or normal. Device.