US 8,607,813 B2Granted

Method for reducing the air feed from the atmosphere into the expansion vessel of high-voltage systems filled with insulating liquid and device for carrying out the method

AssigneeGatron Corporation

InventorEckhard Braesel

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Abstract

A method and apparatus are provided for reducing the oxygen content drawn from the atmosphere that enters the insulating fluid-containing expansion vessel of high-voltage systems. The apparatus is provided with inner and outer tanks that include a liquid that provides a diffusion barrier for capturing oxygen from the atmosphere. The tanks are in communication with the atmosphere on one side of the barrier and in communication with the expansion vessel on the other side of the barrier. Further provided is a moisture-capturing dehumidifier upstream of the diffusion barrier to dry the gas passing into the expansion vessel. The apparatus limits degradation of the insulation system caused by moisture and oxygen, thereby increasing the life span of the high-voltage system. In the method, gas is transferred from the expansion vessel to an external buffer space in the outer tank up to a pre-defined overpressure relative to atmospheric pressure, said gas being discharged to the atmosphere only when the pre-defined overpressure is exceeded. Further, gas is transferred from the external buffer space to the expansion vessel to approach to a pre-defined underpressure relative to atmospheric pressure, with either air from the atmosphere or inert gas being fed to the buffer space when pressure drops below the underpressure. The buffer space volume is correlated to lower and upper working temperatures of the insulating fluid in the high-voltage system, which temperatures are determined based on the geographical location of the system.

Claims15

Dependent claims

A method for reducing the air present in a high voltage power plant comprising:

providing an apparatus comprising:
an expansion vessel having a volume partially filled with an insulating liquid, at least a portion of a remainder of the expansion vessel volume being a space for retaining air from the atmosphere,
a first tank and a second tank positioned inside of and being smaller than the first tank, the first tank and second tank having lids at the tops thereof, the first tank and second tank having a volume partially filled with a diffusion barrier liquid, the first and second tank having a common opening located below a fill line of the diffusion barrier liquid for permitting the movement of liquid between the first and second tank, the first tank having an external buffer space present in a portion of a remainder of the volume of the first tank, the second tank having a compensation space present in a portion of a remainder of the volume of the second tank, a flow line between the space for retaining air from the atmosphere in the expansion vessel and the external buffer space in the first tank, a compensation flow line between an ambient atmospheric environment and the compensation space in the second tank, a pipe positioned in the second tank for permitting air flow between the compensation space and the diffusion barrier liquid;
whereby the diffusion barrier liquid provides a barrier to diffusion of at least the oxygen component of air from an atmosphere side of the diffusion barrier liquid to the external buffer space on an expansion vessel side of the diffusion barrier liquid;
determining the volume of the external buffer space through predetermined designation of an upper working temperature and a lower working temperature of the insulating liquid;
transferring gas in the space in the expansion vessel to the external buffer space up to a predetermined overpressure relative to atmospheric pressure;
transferring gas from the external buffer space to the expansion vessel until attaining a predefined value of underpressure relative to atmospheric pressure;
releasing gas from the external buffer space in the first tank when the predefined overpressure value is exceeded through displacement of the diffusion barrier liquid in the first tank though the pipe in the second tank;
and
drawing gas into the external buffer space from the atmosphere into the first and second tank though the compensation flow line when the pressure in the external buffer space falls below the predefined underpressure value.

7 more elements

An apparatus for lowering the oxygen content of air present in an expansion vessel of a high-voltage power equipment, comprising:

an expansion vessel having a volume partially filled with an insulating liquid, at least a portion of a remainder of the expansion vessel volume being a space for retaining air from the atmosphere;
a first tank and a second tank positioned inside of and being smaller than the first tank, the first tank and second tank having lids at the tops thereof, the first tank and second tank having a volume partially filled with a diffusion barrier liquid, the first and second tank having a common opening located below a fill line of the diffusion barrier liquid for permitting the movement of the diffusion barrier liquid between the first and second tank, the first tank having an external buffer space present in a portion of a remainder of the volume of the first tank, the second tank having a compensation space present in a portion of a remainder of the volume of the second tank, a flow line between the space for retaining air from the atmosphere in the expansion vessel and the external buffer space in the first tank, a compensation flow line between an ambient environment having atmospheric air and the compensation space in the second tank, a pipe positioned in the second tank for permitting air flow between the compensation space and diffusion barrier liquid;
whereby the diffusion barrier liquid provides a barrier to diffusion of at least the oxygen component of air from an atmosphere side of the diffusion barrier liquid and the external buffer space on an expansion vessel side of the diffusion barrier liquid.

Dependencies are inferred from the claim text.