RU145265U1 - POWER TRANSFORMER HOUSING - Google Patents

Abstract

The proposed device relates to the field of electrical engineering and can be used to prevent rupture of the housing of structural elements, mainly transformers, cooled by a large volume of liquid (oil). The proposed device solves the technical problem of protecting the transformer by changing the design of the transformer housing. The stated technical problem is solved in that the power transformer housing is made of two chambers: an outer and an inner one with an active part and bottom holes in the side walls to connect both chambers hydraulically as communicating vessels, while the upper part of the outer chamber is filled with inert gas. Initially, the oil level in both chambers is the same.

Description

The proposed device relates to the field of electrical engineering and can be used to prevent rupture of the housing of structural elements, mainly transformers, cooled by a large volume of liquid (oil). In the event of a short circuit and an arc arising in the active part of the transformer, a large amount of gas is generated during decomposition of the transformer oil. Basically, it is acetylene and hydrogen, which, at high temperature, in contact with air spontaneously ignites, which leads to a fire and serious accidents. The process develops within tens of milliseconds, while the pressure in the tank rises sharply, exceeding critical parameters. Dealing with the consequences of such accidents requires a significant investment in equipment recovery. Therefore, protection of the transformer against explosion requires special attention.

In transformer technology, a protective fire system is known that is driven by various relay type sensors. The disadvantage of these devices is their inertia - the response time is hundredths of a second, which is many times higher than the necessary protection response speed, since the process develops within a few milliseconds (Lizunov S.D., Lokhanin A.K. Power transformers. Reference book. Energy Publishing House, 2004). Therefore, to protect transformers from explosion and destruction, systems with less inertia are needed.

Closest to the proposed solution (its prototype) is a device for preventing the explosion of electrical transformers (patent RU 2263989 from 03/17/2000). This device comprises an oil discharge system connected to the tank by a pipeline. Such systems are used to protect medium and high power transformers. However, the rate of gas evolution when an arc occurs in the oil is extremely high (up to 50 m ³ / s). Therefore, the pressure gradients in the tank and pipelines connecting the tank to the decompression chamber are too large to reduce the pressure in the tank to a safe level in time. Due to the greater pressure drop in the pipeline, the prototype device is not efficient enough and often does not work in severe accidents of powerful transformers.

The proposed device eliminates the disadvantages of the prototype, solving the technical problem of protecting the transformer by changing the design of the transformer housing.

The stated technical problem is solved in that the power transformer housing is made of two chambers: an outer and an inner one with an active part and bottom holes in the side walls to connect both chambers hydraulically as communicating vessels, while the upper part of the outer chamber is filled with inert gas. Initially, the oil level in both chambers is the same.

This set of features provides a quick pressure relief in the tank during a short circuit (short circuit). The resulting gases press on the oil in the inner chamber, like a piston. In the inner chamber, the oil level decreases, respectively, in the outer chamber - it increases due to the compression of the oiled gas cushion.

The essence of the proposed solution is illustrated by the circuit shown in FIG. one.

The housing of the power transformer is made of two chambers, an outer 1 and an inner 2 with an active part and bottom holes 3 in the side walls for connecting both chambers hydraulically as communicating vessels, while the upper part 4 of the outer chamber is filled with inert gas.

The device operates as follows.

During normal operation of the transformer, the oil level in both chambers is the same. When ejected, as a result of a short circuit in the active part, the gases forming in the upper part of the inner chamber 2 press on the oil like a piston. In the inner chamber, the oil level decreases, the oil is pressed through the bottom holes 3 into the outer chamber 1, where the oil level is increased by compressing the inert gas located above it in the upper part 4 of the outer chamber 1. In the inner chamber 2, the pressure decreases due to an increase in the usable volume .

In the proposed device, there is no delay in the time of pressure relief in the transformer tank, since the whole system works as a self-regulating one. In this case, the oil layer between the walls of the inner 2 and the outer 1 of the chambers works as a damper to relieve mechanical stresses of the walls of the inner chamber 2.

In addition, the presence of a fireproof cooling gas cushion located above the oil level in the upper part of the outer chamber will make it possible to quickly reduce the temperature of the surface layer of oil below the flash point when the inner chamber ruptures, as well as prevent the flow of oxygen.

Claims (1)

The case of the power transformer is made of two chambers, the outer and inner, with the active part and bottom holes in the side walls for connecting both chambers hydraulically as communicating vessels, while the upper part of the outer chamber is filled with inert gas.