JPH0569387B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field to which the Invention Pertains] The present invention distinguishes between normal operation and abnormal operation of a winding protection lightning arrester that is connected in parallel to a non-directly grounded winding of an induction electric appliance and has both terminals at a high potential. Regarding monitoring equipment.

[Prior art and its problems]

For ultra-high-voltage, large-capacity power transformers that require increased unit transport capacity through smaller size and lighter weight, autotransformers are often used because their winding capacity is smaller than the line capacity. If the winding is placed on the neutral point side of the winding, the magnetic flux density of the core changes depending on the tap position, and there is a problem that the voltage of the tap winding must be made larger than the required voltage adjustment range. In many cases, the tap winding is provided near the line end of the shunt winding to eliminate the above problem.

FIG. 3 is a schematic structural diagram of a power autotransformer showing the prior art, in which a tank 8 containing an insulating medium 9 such as insulating oil or gas is wound concentrically around the legs of an iron core. An induction electric winding consisting of a shunt winding 1, a series winding 2, and a tap winding 3 is housed, and the line end u (low voltage side) of the shunt winding 1 with the neutral point 0 side grounded, And the line end U (high voltage side) of the series winding 2 where the Tatsu winding 3 is grounded in series is connected to the tank 8.
The u
The structure is such that the voltage between u and o can be adjusted without changing the excitation impedance between -o. However, since the impedance of the external circuit between u and o is generally low, if an abnormal voltage such as a lightning surge is applied to the line end U, most of the abnormal voltage will be borne by the series winding 2 and the tap winding 3. When there is an idle coil 3A that does not pass line current to the tap winding 3, the leakage impedance of the idle coil 3A is large, so
A problem arises in that a large abnormal voltage is applied to the tap winding, threatening the inter-tap insulation of the tap winding 3, the ground insulation, or the insulation of the tap selector.
Reference numeral 5 denotes a protective lightning arrester provided to absorb the abnormal voltage of the tap winding 3 as described above. By suppressing the abnormal voltage in the protective lightning arrester 5,
The above-mentioned problems can be eliminated.

In the induction electric appliance configured as described above, the protective arrester 5 is housed in the tank 8, making visual inspection difficult, and since both terminals of the arrester 5 have a high ground potential, it is difficult to detect the operating current of the arrester. This method has the disadvantage that it is difficult not only to check whether the protective lightning arrester is operating normally, but also to monitor abnormalities such as an increase in leakage current or the occurrence of follow-on current in the lightning arrester.

[Purpose of the invention]

The present invention was made in view of the above-mentioned situation, and
It is an object of the present invention to provide an operation monitoring device that can discriminate and detect surge current and abnormal current of a lightning arrester for protecting an induction electric winding whose both terminals are at a high potential.

[Key points of the invention]

The present invention provides an electrohydraulic converter that operates by detecting the current flowing through a lightning arrester for protecting the winding of an induction device, both terminals of which are at a high ground potential, and is provided on the high potential side together with the lightning arrester. A hydraulic-electrical converter is installed outside the tank of the induction electric equipment, communicating through a pressure pipe and converting changes in hydraulic pressure into on/off electrical signals.
By being configured to include a monitoring device comprising a discrimination circuit that discriminates the duration of the output on/off electrical signal of this hydraulic electrical converter and issues a count signal for a single surge and an alarm signal for a persistent abnormal current. A simple electrohydraulic transducer insulated to the ground by an insulated impulse pipe detects surge current or persistent abnormal current flowing through the lightning arrester, converts it into a change in oil pressure, and transmits it to a hydraulic/electrical transducer placed outside the tank. In addition, the duration of the output on/off signal of the hydraulic-electrical converter can be discriminated by a discrimination circuit to generate a surge current count signal and an abnormal current alarm signal. This allows the occurrence of abnormal current due to runaway etc. to be detected without delay.

[Embodiments of the invention]

The present invention will be explained below based on examples.

FIG. 1 is a schematic configuration diagram showing a device according to an embodiment of the present invention, and the same parts as in the prior art are given the same reference numerals and detailed explanations are omitted. In the figure, 10
is an operation monitoring device for a lightning arrester 5 for protecting induction coil windings, which includes an electrohydraulic converter 11 that detects the current IA flowing through the lightning arrester 5 and converts it into hydraulic pressure, and an electrohydraulic converter placed on the high potential side. An insulated impulse pipe 12 is provided outside the tank 8 so as to electrically insulate the vessel 11 from a grounded metal part such as the tank 8, and to communicate with the insulated impulse pipe 12 which transmits changes in hydraulic pressure from the electrohydraulic transducer 11. a hydraulic-electrical converter 13 for converting oil pressure changes into on/off electrical signals;
It is composed of a discrimination circuit 4 that emits a count signal corresponding to a surge current and an alarm signal corresponding to an abnormal current, and the count signal is displayed by a counter 15 as its frequency of occurrence, and the lightning arrester detects leakage current, follow-on current, etc. exceeding a predetermined level. The alarm device 16 is configured to operate when an abnormal current is detected.

FIG. 2 is a sectional view of the main parts of the embodiment device. In the figure, the electrohydraulic converter 11 is composed of a solenoid coil 24 connected in series to the lightning arrester 5, a piston rod 23, and a piston cylinder 22 that are driven by the electromagnetic force of the current flowing through the solenoid coil 24. Current IA
is transmitted to the hydraulic-electrical converter 13 without delay as a pressure increase in the hydraulic oil 21 in the piston cylinder via an insulated impulse pipe 12 made of an oil-resistant pressure rubber pipe, a synthetic resin pipe, or the like. The hydraulic-electrical converter 13 includes a piston cylinder 32 communicating with the insulated impulse line 12;
A hydraulic mechanism section consisting of a piston rod 33 and a compression coil spring 35 that senses the pressure increase of the hydraulic oil 21.
The pressure sensitive switch 34 is driven by a piston rod 33 that moves in the direction of compressing the pressure sensitive switch 34.
It is formed of a pressure sensitive conductive rubber sheet 34A having a pressure sensitive conductive rubber sheet 34C, is supported on the piston cylinder side by an insulating plate 34E, and is brought into contact with the tip of the piston rod 33 via a pressing plate 34D, thereby sensing the slight movement of the piston rod 33. The pressure sensitive switch 34 can be controlled to be turned on or off.
Note that a metal pressure impulse tube can be used for the portion of the insulated impulse tube 12 outside the tank 8.

Generally, the lightning surge current flowing through the lightning arrester 5 is short-lived and sporadic, whereas for example, follow-on current due to an increase in AC leakage current due to deterioration of the element of a zinc oxide arrester or thermal runaway of the element is persistent. . Therefore, by configuring the discrimination circuit 14 with a relay system consisting of an instantaneous relay that detects surge currents and a relay with a time-limiting element that detects persistent abnormal currents, discrimination is possible. Abnormal current can be output as a count signal and as an alarm signal, respectively. Furthermore, it goes without saying that the relay system may be configured with a non-contact circuit.

In the above embodiment, the operation monitoring device is connected to the tap winding 4 at a high potential of the power autotransformer.
Although an example in which the present invention is used for protection has been shown, it goes without saying that the same function as in the embodiment can be obtained by applying the present invention to a winding of a non-grounded induction electric device that is not grounded or is grounded with low resistance.

〔Effect of the invention〕

As mentioned above, the present invention consists of an electromagnetic hydraulic converter placed in a high potential section that detects the current flowing through a surge arrester for protection of induction electric equipment at a high potential and converts it into a hydraulic pressure change, and an electromagnetic It is arranged outside the tank so as to communicate with the hydraulic pressure converter, and turns on/off the hydraulic pressure change.
A lightning arrester operation monitoring device consisting of a hydraulic-electrical converter that converts into an OFF electrical signal, and a discrimination circuit that receives the OFF electrical signal, discriminates between surge current and abnormal current based on its duration, and issues a count signal and alarm signal. It was configured to provide. the result,
The current flowing through the lightning arrester is converted into hydraulic pressure by an electro-hydraulic converter consisting of a solenoid coil and a hydraulic piston connected in series with the arrester, and converted into an on/off electrical signal by a hydraulic-electrical converter.The current flowing through the lightning arrester is converted into an on/off electric signal by a hydraulic electric converter, and the surge current is determined from the duration of the current. In addition to making it possible to discriminate abnormal currents, the ground insulation of the electrohydraulic converter, which is at a high potential along with the lightning arrester, is maintained by the insulated impulse tube, which eliminates the possibility of detecting current that is difficult to detect due to the high ground potential of the lightning arrester. The problems of the conventional technology have been eliminated, and the present invention has developed an induction arrester that has excellent monitoring performance that can distinguish and detect the number of surge current occurrences (number of operations) and abnormalities in the arrester using a small and simple device. We were able to provide an operation monitoring device.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing an example device of the present invention, FIG. 2 is a sectional view of main parts in the example device,
FIG. 3 is a block diagram showing the prior art. 1...Shunt winding, 2...Series winding, 3...Tap winding, 5...Protective arrester, 9...Tank, 1
0...Operation monitoring device, 11...Electrohydraulic converter,
12... Insulated impulse pipe, 13... Hydraulic electrical converter,
14...Discrimination circuit, 21...Hydraulic oil, 22, 32
... Piston cylinder, 23, 33 ... Piston rod, 24 ... Solenoid coil, 34 ... Pressure sensitive switch.

Claims (1)

[Claims] 1. In a device having a protective lightning arrester connected in parallel to the non-direct grounding winding of an induction electric device housed in a tank containing an insulating medium, the device operates by detecting the current flowing through the protective lightning arrester installed in the tank. an electrohydraulic transducer that is connected to the electrohydraulic transducer; and a hydroelectrical transducer that is disposed outside the tank so as to communicate with the electrohydraulic transducer via an insulated impulse pipe, and that converts changes in the hydraulic pressure of the electromagnetic hydraulic transducer into an on/off electrical signal. and a discrimination circuit that discriminates the duration of the output electrical signal of the hydraulic-electrical converter and outputs a surge current count signal and an abnormality alarm signal. Device.