JP2007043026A - Gas-in-oil alarm relay - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect a concentration of gas-in-oil of a transfer insulation oil without contacting with the insulation oil after passing through a conservator diaphragm and safely and easily mount a transfer without anxiety for oil leakage etc., even if it is a mounted transfer in operating or a newly mounted transfer. <P>SOLUTION: The gas-in-oil alarm relay is composed of (α) a level setting switch which sets a relation between a specified gas concentration alarm level of a gas-in-oil and a passing through specified gas concentration to be detected according to the specification of the transfer to be provided with the gas-in-oil alarm relay and conservator, (β) a gas sensor to detect a passing through specified gas which is held in a water proof socket mountable between the outlet of the conservator chamber and a humidity absorbing breather, and (γ) a cable which connects a detection/display circuit held in a casing and a data transferring circuit. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

Detailed Description of the Invention

Industrial application fields

  The present invention relates to gas monitoring in transformer oil, which is one of the most important monitoring items related to transformer maintenance, and is constantly monitored without sampling the transformer insulation oil and without contact with the insulation oil. It is an alarm relay that contributes to prediction and prevention of internal accidents, and can be applied to all transformers, whether newly installed or existing, to detect the gas that has passed through the conservator diaphragm.

As a method of internal diagnosis of a transformer, it is common to extract insulation oil from the transformer, analyze the gas contained in the insulation oil using a gas chromatograph, and diagnose the presence or absence of internal abnormality by its component ratio. is there. This is not only costly for oil collection, sample transportation, analysis, etc., but it is inevitable that prediction of internal abnormality of the transformer will be delayed by periodic analysis once or twice a year.
On the other hand, a constant monitoring type in-oil gas detection device has been developed in response to the demand for constant monitoring, but this conventional device is directly attached to a transformer to guide insulating oil to a gas permeable membrane in the device. There is a need. Further, unless the insulating oil in contact with the gas permeable membrane is constantly replaced by convection, the gas in the oil is not detected over time. Therefore, there are restrictions on the installation location, piping length, piping shape, valves used, etc., and even if it can be installed in a new transformer, a corresponding construction cost is required. Needless to say, it is impossible to install in an existing transformer as long as it is necessary to direct the insulating oil directly to the transformer.

Problems to be solved by the invention

  In view of the above-described state of the prior art, the present invention intends to provide an always-monitoring oil-in-gas alarm relay that can be installed in all transformers regardless of existing or new installations.

Means to solve the problem

The present invention a) Determines the specific gas concentration permeating the conservator diaphragm as a function of the specific gas concentration in the known oil, the material and shape of the conservator diaphragm, the internal pressure of the insulating oil, etc. Formulate the relationship between the specific gas concentration alarm level in oil and the permeated specific gas concentration from the specifications of the transformer and conservator installed,
B) A gas sensor that detects the permeation specific gas is housed in a socket that can be installed between the outlet of the conservator air chamber or the hygroscopic respirator,
C) By connecting the detection / display circuit and data transmission circuit housed in the chassis with a cable, the gas concentration in the oil can be constantly monitored at locations isolated from the insulating oil, and can be easily installed in existing transformers. If possible, it solves the above problems.

Action

The gas in the insulating oil is generated due to poor contact within the transformer or arc due to short circuit and deterioration of the insulator, and hydrogen, methane, ethane, ethylene, acetylene, etc. are generated due to the generation factor. These gases pass through the diaphragm of the conservator that compensates for the expansion and contraction of the insulating oil and prevents oxidation of the insulating oil due to the internal pressure of the insulating oil, etc., and the hygroscopic respirator installed in the conservator air chamber and the air outlet It stays in the pipe up to. Of course, since the hygroscopic respirator is open to the atmosphere, the permeated specific gas concentration ρ at any position X during this period is the following equation (1), assuming that the specific oil gas concentration ρ ₀ and the internal pressure are constant: It settles to the value represented by.
ρ = K · A · ΔP · ρ ₀ · (X ₀ −X) / (tDa) (1)
here,
a: Hygroscopic respiratory entrance area X ₀ : Distance from conservator diaphragm to hygroscopic respiratory outlet X: Distance from conservatory diaphragm to oil gas alarm relay installation position D: Specific gas-to-air diffusion coefficient K: Diaphragm Specific gas permeation coefficient A: Diaphragm area t: Diaphragm thickness ΔP: Differential pressure between conservator gas phase part and liquid phase part (internal pressure) ρ _O : Gas concentration in specific oil.
As shown in the above formula (1), the concentration to be detected decreases as the distance from the conservator diaphragm decreases. However, when an oil-in-gas alarm relay is installed at a position away from the conservator diaphragm, the load on the transformer increases. It is also possible to detect a high-concentration gas immediately after the diaphragm pushed toward the hygroscopic respirator due to the displacement of the conservator diaphragm accompanying an increase in ambient temperature or the like. The above-mentioned factor of the diaphragm displacement is a daily change. Therefore, if the peak change of daily change is taken, the concentration immediately after the diaphragm can be grasped in units of one day at an arbitrary position from the conservator diaphragm to the hygroscopic respirator.
Furthermore, the correlation between the specific oil gas concentration (ρ _O ) and the detected concentration (ρ) is obtained from the above equation (1) and the specifications of the transformer to be monitored.
The above-described gas in oil may be specified arbitrarily, and the detection gas may be specified according to the content of the abnormality inside the transformer, or hydrogen that is most easily transmitted through the conservator diaphragm may be represented.

  Hereinafter, embodiments will be described with reference to the drawings.

FIG.

Shows the concept of gas detection in oil and the installation position and schematic configuration of the oil alarm relay in oil.
The gas generated by the abnormality in the transformer (1) dissolves in the insulating oil (2), but passes through the diaphragm (4) of the conservator (3) and passes between the diaphragm (4) and the hygroscopic respirator (5). It stays with a concentration gradient. The oil-in-gas alarm relay (6) of the present invention can be attached at any position between the diaphragm (4) and the hygroscopic respirator (5), but in this embodiment, it is attached immediately before the hygroscopic respirator (5). It is. The hydrogen detection gas sensor (7) is housed in the waterproof socket (8) and connected to the alarm display box (10) via the cable (9). In the alarm display box (10), a detection circuit, a level setting switch (11), a display circuit and a data transmission circuit are incorporated so that the alarm signal can be transmitted to the monitoring station and the level of the detected concentration for on-site monitoring. Alarm lamps (12) and (13) according to the above are provided on the surface of the alarm display box (10). The level setting switch (11) is an internal switch for setting an alarm level from the correlation between the gas concentration in specific oil (ρ _O ) and the detected concentration (ρ).
In this embodiment, hydrogen having a large membrane permeability coefficient is selected and specified as a gas in oil, and a hydrogen detection gas sensor is used. However, as described above, another gas in oil is selected and specified, and a gas sensor corresponding to this is selected. It is possible to employ a sensor that is sensitive to various types of gases in order to increase sensitivity.
It is also easy to digitally display the detected concentration on the surface of the alarm display box instead of the alarm lamp.

The invention's effect

  The effect of the present invention is that the gas concentration in the oil of the transformer insulating oil can be detected after passing through the conservator diaphragm without being in contact with the insulating oil. By providing a medium gas alarm relay, the internal abnormality of the transformer can be constantly monitored regardless of the existing transformer or the new transformer that is in operation.

  The concept of oil-in-gas detection and the installation position and schematic configuration of the oil-in-gas alarm relay are shown.

Explanation of symbols

1. ... Transformer ... Insulating oil ... Conservator 4. ... Diaphragm 5 ... Hygroscopic respirator ... Gas alarm relay in oil ... Gas sensor for hydrogen detection ... Waterproof socket 9. ... Cable 10. ... Alarm display box ... Level setting switch ... Alarm lamp 13 ... Alarm lamp

Claims (1)

  An alarm relay consisting of a gas sensor for detecting abnormal gas generated in the transformer insulating oil in the gas phase after passing through the conservator diaphragm, a detection / display circuit that outputs an alarm signal according to the gas concentration, and a signal transmission circuit.

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