Transformer weak gas guard job curing analysis and remediation

The main reason for the gas protection action is to send a signal to the light gas protection action (hereinafter referred to as “light gas protection action”), and it should be carefully examined, carefully analyzed, and correctly judged, and immediate measures should be taken to prevent the failure from expanding. Transformer gas relay has buoy type, baffle type, open cup and other different models. At present, most of the QJ-80 type gas relays are used, and the signal circuit is connected to an open cup, and the trip circuit is connected to the lower baffle. The so-called light gas protection operation means that the signal circuit contact point of the opening cup in the gas relay is closed due to various reasons, resulting in a light gas protection operation. The reasons for the closure of the signal circuit contacts generally have the following aspects. The air enters the transformer gradually accumulates in the upper part of the gas relay, forcing the oil surface in the gas relay to drop, closing the reed contact and issuing a light gas protection action signal. There are three ways for the air to enter the transformer in operation: First, when the transformer is changing oil or replenishing oil, the oil to be exchanged or supplemented is not completely vacuum degassed, and the vacuum oil injection process is strictly performed to make the air in the oil, Attached to the core, windings, resulting in light gas protection action. There is a discharge or overheat fault inside the transformer, which causes decomposition of solid insulating materials, decomposition of transformer oil, generation of hydrogen, carbon monoxide, carbon dioxide, and low molecular hydrocarbon gases. These gases gradually become air bubbles with the oil's convective circulation and rise to gather in the upper part of the gas relay. Forcing the gas surface in the gas relay to drop, causing a light gas protection action.

Identification of gas in gas relays. Ignition and chromatographic analysis of gas. The “Power Transformer Operation Regulations” stipulates that if there is gas in the gas relay, the gas volume should be recorded, the color of the gas should be observed, and the test be flammable and the gas sample and oil sample should be analyzed by chromatography. Ignition test is to use the gas collected by the syringe and use the match to ignite from the gas release nozzle. If the gas itself can spontaneously ignite and the flame is light blue, it is a flammable gas, which indicates that the internal of the transformer is faulty. If it cannot be spontaneously ignited, it is air, which indicates that the signal action is caused by air entering. Chromatographic analysis refers to the qualitative and quantitative analysis of the collected gas with hydrogen, oxygen, carbon monoxide, carbon dioxide, methane, ethane, ethylene, acetylene, and other gases, and accurately determines the failure based on the name and content of the contained components. Nature, development trend and severity.

Ignition test and chromatographic analysis are two different methods for judging whether there are faults inside the transformer. The purpose is the same. The ignition test is a method that is specified before the chromatographic analysis of the gas contained in the sample is performed. This method is simple and convenient. It judges whether the accuracy is related to the quality and experience of the test personnel, but it cannot judge the nature of the fault. Since the method of transformer operation has not been cancelled since the introduction of the chromatographic method, it is possible to quickly determine whether the transformer is faulty at the site, but due to factors such as whether the on-site personnel can properly collect gas, whether it can properly ignite, and accurately judge, it is not acceptable. To the desired effect.

Do ignition test or chromatographic analysis, since the volume setting of the gas relay relay is 250-300ml, theoretically, as long as the signal operates, approximately 250-300ml of gas can be collected. Two tubes can be collected with a 100 ml syringe. One tube can be used for ignition test in the field and the other tube for chromatographic analysis. Transformer internal faults sometimes develop rapidly, and the gas produced does not saturate in the oil and accumulates in the gas relay. If the signal is not collected in time, if the time is too long, part of the gas will be dissolved and lost in the oil. The collected gas may be less than 100 ml. If it is collected with a 100 ml syringe, the ignition test should not be done and it should be done quickly. spectrum analysis. This conflicts with the regulations of the transformer operating procedures. The solution to this contradiction is to collect gas with two small-capacity syringes (not less than 10 ml each). If the transformer is close to the chromatographic laboratory, ignition test is not required. If the on-site operator is trained to have the ability to collect and perform ignition tests, the operator should be responsible for this task. If this capability is not available, relevant professionals should be responsible for this work.

After transformer light gas protection action processing transformer light gas protection action processing principle is: immediately stop the sound signal, check the transformer temperature, sound, oil level and voltage, current indication. And external inspection of the transformer, listening to whether the sound changes, whether the oil level is reduced, check the riot tube, casing and other breakage and fuel injection phenomenon, check whether the relief valve action.