JPH05283240A - Oil-filled transformer - Google Patents

Abstract

PURPOSE:To obtain an oil-filled transformer in which whether a monitor is abnormal or the transformer is abnormal can be confirmed at the time of generating an abnormal signal by continuously monitoring an operating state of the transformer. CONSTITUTION:The oil-filled transformer comprises an oil level sensor 6 of insulation oil in a transformer tank 1, a monitor 8 for storing, calculating and displaying a detection signal from a temperature sensor 5, an abnormal signal generator 9 for outputting an abnormal signal according to data from the monitor 8, and a unit for detecting and displaying oil level and temperature of the oil independently from the monitor 8. When the generator 9 generates the signal, whether the monitor 8 is abnormal or the transformer is abnormal can be confirmed according to data of the unit for independently displaying oil level and temperature of. Further, a pressure sensor 7 is used together to detect rise of an internal pressure of the tank l and accumulation of decomposed gas.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil-filled transformer using an insulating oil such as mineral oil as an insulating and cooling medium.

[0002]

2. Description of the Related Art A conventional oil-filled transformer will be described with reference to FIG. As shown in the figure, various protective devices are attached to the oil-filled transformer. That is, the transformer tank body 1
An oil temperature gauge 11 for displaying the temperature of the insulating oil and an impact hydraulic relay 13 for detecting an abnormal rise in the tank pressure due to an internal arc accident and generating an abnormal signal are attached. In addition, the oil pipe 1 is attached to the upper part of the transformer tank body 1.
A conservator 2 is attached via 5. Inside the conservator 2, an oil level gauge 12 that displays the volume of oil that changes with the oil temperature at the oil level position, and decomposed gas in the insulating oil accumulates in the middle of the oil pipe 15, Gas detection relay 14 that generates an abnormal signal when the amount of gas exceeds a specified amount
Is installed.

Among these protective devices, the oil level gauge 12 and the oil temperature gauge 11 are dial type ones in which a pointer is operated by using a float or a Bourdon tube, and the oil level position and the oil temperature are dial-displayed on a scale plate. It is common. The oil level gauge 12 and the oil temperature gauge 11 are each provided with a contact that operates when the oil level position or the oil temperature exceeds a specified range, and the signal of this contact is transmitted through the abnormal signal transmission path 17. There is an external sequence that triggers an alarm and shuts down the transformer.

Normally, the gas detection relay 14 is the tank body 1
It is installed in the middle of the oil pipe 15 that connects the and the conservator 2, and initially the case of the gas detection relay 14 is filled with insulating oil, but when decomposition gas is generated, that gas accumulates in the case. Push down the oil. At this time, the float in the case is pushed down to activate the contacts. The oil level position of the oil level gauge 12 can be observed from the outside through a viewing window. Further, the impact hydraulic relay 13 does not have a display function, and only the contacts that operate when the specified range is exceeded are attached.

[0005]

By the way, a micro switch is usually used as a contact attached to all protective devices. Periodic calibration and replacement were indispensable because there is a possibility that misalignment may occur due to misalignment due to vibration during operation.

[0006] In general, the protective device is mounted directly on the tank body of the transformer or inside the collective terminal box near the tank body, and the display of the scale plate is displayed during regular inspection by maintenance personnel. Recorded by maintenance personnel. Therefore, it is not possible to continuously monitor the oil level and the tendency of changes in oil temperature, and if an oil leak is to be investigated, the regular oil level should be calculated from the read oil temperature data and It is necessary to compare with the indicated value of the surface gauge. Also, the oil temperature inside the transformer is not constant, and in order to calculate the normal oil level, the average temperature of the oil must be calculated from the indicated value of the oil thermometer that indicates the maximum temperature of normal oil. Data processing was also complicated.

As a solution to these problems, a method has been proposed in which the oil level and the oil temperature are detected as electric signals and continuously monitored. However, sensor monitoring currently only provides a supplementary role to the mechanical protection device. For example, a dial-type oil thermometer is attached to the tank body of a transformer, and the temperature measured by a temperature sensor of a resistance thermometer is separately captured and recorded in the control panel of the control room. The current situation is that the information on alarm generation and transformer stoppage in the event of an abnormality depends on the operation of the microswitch of the mechanical protection device. Further, since the oil level changes depending on the load and the oil temperature, there is a large error in the method of judging the oil leakage only by the decrease of the oil level.

In order to avoid double monitoring by using such a mechanical protection device and a sensor in combination, it is conceivable to use a single monitoring method without using a mechanical protection device.
However, in the substation where the transformer is installed, high-voltage equipment is in operation, and when disconnecting these equipment from the circuit, surge voltage may occur and affect the electrical signal of the monitoring equipment and malfunction. It cannot be said that there is no. When the abnormal signal generation circuit outputs an abnormal signal due to such a malfunction, it is impossible to confirm whether it is normal or abnormal by monitoring only the sensor.Therefore, the transformer must be stopped even if the transformer itself is not abnormal. There was a possibility that it might not happen.

The present invention has been made in view of the above circumstances, and its purpose is to continuously monitor the operating state of a transformer and eliminate contacts such as microswitches necessary for a mechanical protection device to generate an abnormal signal. It is an object of the present invention to provide an oil-filled transformer that can easily confirm whether the signal is due to an abnormality of the monitoring device or an actual abnormality of the transformer.

[0010]

In order to achieve the above object, the present invention provides an oil level sensor for detecting an oil level of insulating oil contained in a tank body of a transformer, and a temperature of the insulating oil. Temperature sensor for detecting temperature, a monitoring device for taking in, storing, calculating, and displaying detection signals from the respective sensors, and an abnormal signal generating circuit for inputting data from the monitoring device and outputting an abnormal signal in the case of an abnormality And a display device that detects the oil level and temperature of the insulating oil by a mechanism independent of the monitoring device and displays the detected value, but does not have a function of generating an abnormal signal for the abnormal detected value. It is characterized by

[0011]

According to the present invention, it is possible to continuously monitor the oil leakage by comparing the measured value of the oil level of the oil-filled transformer with the regular oil level calculated from the oil temperature. Further, by using the pressure sensor together, it is possible to detect both the rapid increase in the internal pressure and the accumulation of decomposed gas, so that the oil level gauge with contact and the oil temperature gauge used for the conventional monitoring are all unnecessary. On the other hand, since the oil level gauge and oil temperature gauge without contacts are installed, even if the monitoring device malfunctions due to an abnormal signal, etc., it is possible to confirm whether or not it malfunctions by comparing with the oil level gauge or oil temperature meter. You can easily.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of an embodiment of the present invention. As shown in the figure, the conservator 2 is attached to the upper portion of the transformer tank main body 1 via an oil pipe 15. A gas reservoir case 10 is provided in the middle of the oil pipe 15, and the case 1
A pressure sensor 7 for detecting the accumulation of decomposed gas is attached to the inside of zero. Further, a pressure sensor 7 for detecting the tank internal pressure is attached to the wall of the tank body 1. The oil temperature in the tank body 1 is measured by the temperature sensor 5.

The temperature sensors 5 are mounted in the tank body 1 at two locations, namely, an upper portion where the oil temperature is highest and a lower portion where the oil temperature is lowest.
If the temperature is measured at two points above and below in this way, the average value of them is almost the average temperature of the insulating oil, so the proper position of the oil level can be known without taking in the load factor and other temperature information, and the oil level sensor It can be compared with the value of 4. Since the oil level gauge 4 has a structure in which the conservator 2 is arranged above the tank body in this embodiment, it is attached to the upper part of the conservator 2. Others For nitrogen-filled type with nitrogen filled in the top of the tank body, install it on the top of the tank cover.

Output signals from the temperature sensor 5, the oil level sensor 6 and the pressure sensor 7 are sent to the monitoring device 8. The monitoring device 8 is generally installed in a place apart from the transformer, such as a control room. On the other hand, a mechanical oil level gauge 4 and a dial thermometer 3 are attached to the tank body 1 of the transformer, but these instruments are not used for normal monitoring, but for confirmation when the monitoring device 8 itself malfunctions. To use. Therefore, a contact that outputs an abnormal signal when an abnormality occurs in the transformer itself is not attached. Reference numeral 9 is an abnormal signal generating circuit, 16 is an oil level, and 17 is an abnormal signal transmission path.

By the way, as the temperature sensor 5, for example, a resistance temperature detector or the like for measuring the temperature by the resistance value of the resistance element which changes corresponding to the temperature is used. As the oil level sensor 6, for example, there is one that obtains the position from the reflection time by utilizing the property that ultrasonic waves are reflected at the oil level position. The pressure sensor 7 may be, for example, one using a strain gauge or a differential inductance type.

Next, the operation of this embodiment will be described.
Output signals from the temperature sensor 5, the oil level sensor 6, and the pressure sensor 7 are sent to the monitoring device 8 via an electric cable or an optical cable via a converter. The monitoring device 8 receives these signals and records them as oil surface temperature, oil surface level or pressure value, and also calculates and records necessary information.
For example, the appropriate level of the oil level is obtained by correcting the oil temperature with the average temperature. However, since the temperature measured by the temperature sensor 5 is the maximum oil temperature, it cannot be used in that range. in this case,
If the load of the transformer and the temperature of the air or water that cools the insulating oil that is the insulating cooling medium are known, the average temperature of the oil can be calculated, and then the normal oil level 16 is calculated, and the oil level sensor 6 It can be compared with the detected value. Further, if the signal from the pressure sensor 7 is taken in at a pitch of 100 ms, an arc accident occurs inside the transformer, and it becomes possible to detect an accident when gas is generated and the internal pressure sharply rises.

As described above, the monitoring device 8 has a thermometer and an oil level gauge, which are conventionally attached to a transformer, and an impact hydraulic relay, if the load factor of the transformer and the temperature information of the medium for cooling the oil are given. In addition to satisfying all functions, it is possible to add functions that are superior to conventional protection devices such as recording data, displaying the presence or absence of oil leakage, and improving accuracy.

[0018]

As described above, according to the present invention,
By detecting the oil surface position and oil temperature in the tank of the oil-filled transformer as an electric signal with a sensor and inputting them to the monitoring device, all the monitoring items that were conventionally provided by the contact protection device can be performed, and additional functions such as recording are also available Can be added. Furthermore, by providing a thermometer or oil level gauge without contacts in the transformer body, it is easy to confirm even if the monitoring device malfunctions.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an oil-filled transformer according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a conventional oil-filled transformer.

[Explanation of symbols]

1 ... Transformer tank, 2 ... Conservator, 3 ... Oil thermometer, 4
... Oil level gauge, 5 ... Temperature sensor, 6 ... Oil level sensor, 7 ... Pressure sensor, 8 ... Monitoring device, 9 ... Abnormal signal generation circuit, 10 ...
Gas reservoir case, 11 ... Oil temperature gauge with contacts, 12 ... Oil level gauge with contacts, 13 ... Impact hydraulic relay, 14 ... Gas detection relay,
15 ... Oil piping, 16 ... Oil level, 17 ... Abnormal signal transmission path.

Claims (1)

[Claims] 1. An oil level sensor for detecting an oil level of insulating oil housed in a tank body of a transformer, a temperature sensor for detecting a temperature of the insulating oil, and a detection signal from each sensor. Monitoring device for storing, calculating, and displaying, an abnormal signal generating circuit for inputting data from the monitoring device and outputting an abnormal signal in the case of an abnormality, and an oil level of insulating oil by a mechanism independent of the monitoring device. An oil-filled transformer comprising: a display device which detects a temperature and displays the detected value, but does not have a function of generating an abnormal signal for the abnormal detected value.