GB2583961A

GB2583961A - Transformer breather

Info

Publication number: GB2583961A
Application number: GB1906905.3A
Authority: GB
Inventors: Michael Hoyle Christian
Original assignee: ENTEXOL Ltd
Current assignee: ENTEXOL Ltd
Priority date: 2019-05-16
Filing date: 2019-05-16
Publication date: 2020-11-18
Also published as: GB201906905D0; IES87209Y1; IE20200105U1

Abstract

An oil filled transformer 7 with oil expansion and contraction method and means, comprises: a vessel 3 arranged external to a transformer 7 and a transformer conservator tank 5 which is in sealed fluid communication with the interior of the conservator tank 5 to capture and store air received from the conservator tank and is sealed to prevent air exchange between the vessel 3 and the atmosphere around the vessel. The vessel 3 may be expandable upon receiving air from the conservator tank 5 and may take the form of a bag with flexible walls which may include one or more elastomeric material portions. Expansion means may be built into the vessel 3. The interior of the vessel may be sealed, at all times, from the surrounding atmosphere. The said sealed fluid communication may be via a fluid manifold 9 coupled to a vessel port 11. The vessel 3 may avoid containing a hygroscopic substance but a container 15 located in the said fluid manifold 9 may contain a hygroscopic substance. The container may include means allowing the visible inspection of the hygroscopic substance from outside the container. The fluid manifold 9 may include a bi-directional pressure relief valve 21 for pressure spikes. The said means may be retrofitted to an existing transformer.

Description

TRANSFORMER BREATHER

Field of the Invention

The present invention relates to a transformer breather for oil filled transformers.

Background to the Invention

A transformer breather is a component of an oil filled transformer which is attached to the conservator tank of the transformer. A conservator tank is a cylindrical tank mounted on the roof of the main tank of the transformer to provide a space to accommodate expansion of oil within the transformer. Transformer oil heats and cools during the normal operation of the transformer. This causes the oil to expand and contract. The conservator tank acts as a reservoir for the expanded oil. The expanded oil pushes air out of the conservator tank through the transformer breather into the atmosphere. When the oil cools down, it contracts and sucks fresh air from the atmosphere through the transformer breather back into the conservator tank. This process is referred to as "breathing" of the transformer. Currently, a typical transformer breather comprises a canister provided on the outside of the conservator tank and filled with a hygroscopic substance such as silica gel. The silica gel absorbs the moisture from the air being "inhaled" by the transformer to ensure that the transformer does not take in moist air. Moisture is hazardous for transformer oil or the transformer as it intensifies corrosion and is detrimental to the insulating properties of the transformer oil. Silica gel needs to be replaced frequently as it reaches the limit of its hygroscopic capacity after a certain number of breathing cycles. Since silica gel is a hazardous substance it needs to be disposed of carefully. This renders the replacement process costly and cumbersome. Some network operators require complete transformer switch outs to facilitate replacement of silica gel. This results in user inconvenience and economic loss due to downtime. Furthermore, silica gel is not always replaced when required. This causes damage to transformers due to corrosion and loss of insulation.

Some transformer manufacturers fit a bladder into the conservator tank on transformers.

The bladder is placed inside the conservator tanks to allow for expansion/contraction of oil whilst isolating the air in the conservator tank from the oil to minimise any adverse effects of the air coming into contact with the oil or the interior of the conservator tank. These bladders do not eliminate the need to have a breather to accommodate air expelled from the bladder.

In view of the above, it is an object of the present invention to alleviate and mitigate the above disadvantages.

Summary of the Invention

According to a first aspect, the present invention provides a transformer breather arrangement for oil filled transformers, the transformer breather arrangement comprising: a breather vessel adapted to be installed externally in relation to a transformer conservator tank of a transformer; the breather vessel being adapted to be arranged in sealed fluid communication with the interior of the conservator tank; the breather vessel being adapted to capture and store air received from the interior of the conservator tank; and wherein the breather vessel is sealed to prevent any air exchange between the interior of the breather vessel and the atmosphere.

Preferably, the breather vessel is expandable. Preferably, the breather vessel is adapted to expand upon receiving air from the conservator tank. The expandable breather vessel provides a visual indication of air movement between the conservator tank and the breather vessel. The breather vessel may be free from an enclosure.

The breather vessel may be provided in the form of bag, but the invention is not in any way limited thereto.

Preferably, the breather vessel has flexible walls.

The walls of the breather vessel, or at least one or more portions thereof, may be made from an elastomeric material so as to enable greater degree of expansion of the breather vessel in order to accommodate greater quantity of air exhaled from the conservator tank.

In a preferred embodiment, the interior of the breather vessel is sealed from the atmosphere to prevent any air retained in the interior of the breather vessel from escaping into the atmosphere. This also prevents any moisture ingress from the atmosphere into the breather vessel and the conservator tank and ensures that the conservator tank breathes dry air at all times. Preferably, the interior of the breather vessel is sealed from the atmosphere at all times.

Preferably, the transformer breather arrangement comprises a fluid manifold for connecting the respective interiors of the breather vessel and the conservator tank and providing the sealed fluid communication with the interior of the conservator tank. The breather vessel preferably has a port between its exterior and its interior and the fluid manifold is preferably coupled to the breather vessel via the port so that air exchange between the interior of the breather vessel and the fluid manifold takes place directly via the port.

As the transformer oil heats or cools, air exchange takes place between the interior of the conservator tank and the interior of the breather vessel. Oil expansion displaces air from the conservator tank into the fluid manifold, from which the air is received in the breather vessel via the port. Oil cooling and contraction causes a reverse process, i.e. air is sucked back from the breather vessel into the conservator tank via the port and the fluid manifold. During this process, due to the breather vessel being isolated from the atmosphere at all times, no air exchange occurs between the interior of the breather vessel and the atmosphere. The breather vessel inflates of deflates accordingly as it receives or releases air. Preferably, the inflation initially occurs due to the flexibility of the material of the breather vessel, i.e. the incoming air inflates previously collapsed walls of the breather vessel. This occurs until a predetermined amount of air has entered the breather vessel. In one arrangement, any further increase in the quantity of air inside the breather vessel is accommodated by the expanding property of the breather vessel. The expanding property may be achieved by making the breather vessel or at least a portion thereof from an elastomeric material to allow the breather vessel to expand and contract in accordance with the quantity of air received in the interior of the breather vessel. Alternatively or additionally, an expansion arrangement may be built into the breather vessel, such as, for example, a bellows-type expansion arrangement or an elastomeric membrane. The expansion arrangement accommodates more of the incoming air and keeps the pressure within the breather vessel at the same level, or at least within allowed predetermined minimal fluctuations. Other expansion arrangements are envisaged as will be apparent to the person skilled in the art.

It will be appreciated that in other embodiments the breather vessel may be rigid.

Preferably, the interior of the breather vessel is free from a hygroscopic substance. The breather vessel of the invention eliminates the need to re-place the hygroscopic substance and thus reduces maintenance costs and potential downtime.

The transformer breather arrangement may comprise a container with a hygroscopic substance, the container being provided along the fluid manifold upstream of the breather vessel and having at least a pair of ports, a first port for fluid exchange between the container and the conservator tank and a second port for fluid exchange between the container and the interior of the breather vessel. The hygroscopic substance may be any suitable hygroscopic substance, such as, for example, but not limited thereto, silica gel. Thus, in use, prior to being received in the breather vessel, air exhaled from the conservator tank passes through the container and through the hygroscopic substance. Thus, the container serves as a backup safety device in case the breather vessel fails. In case of failure of the breather vessel, the container will continue to maintain air movement to and from the conservator tank, whilst filtering any moisture which may be contained in the air being inhaled by the conservator tank. As long as the breather vessel is working correctly, the hygroscopic substance will never need to be replaced. If the breather vessel fails, the hygroscopic substance will change colour due to contact with moisture from the atmosphere and provide a visual indication of failure within the transformer breather arrangement. Preferably, the container is configured such that at least a portion of the hygroscopic substance within the container is visible from the outside.

The transformer breather arrangement may also comprise a bi-directional pressure relief valve installed in the fluid manifold upstream of the breather vessel to accommodate unexpected pressure spikes. The bi-directional pressure relief valve may be installed in the fluid manifold between the breather vessel and the container.

The breather vessel of the invention replaces the prior art breather canister that contains hygroscopic substance and exchanges air with atmosphere. The breather vessel can be retrofitted on existing conservator tanks.

The transformer breather arrangement may comprise a conservator tank monitor adapted to monitor conservator tank oil level, temperature and moisture. The monitor is preferably adapted to indicate breather vessel failure based on the conservator tank oil level, temperature and moisture readings and alarm this condition. The monitor may be located on and/or in the conservator tank.

According to a second aspect, the invention provides a method of operating a transformer breather arrangement for oil filled transformers, the method comprising the steps of: a) providing a transformer breather arrangement comprising: a breather vessel adapted to be installed externally in relation to a transformer conservator tank; the breather vessel being adapted to be arranged in sealed fluid communication with the interior of the conservator tank; the breather vessel being adapted to capture and store air received from the interior of the conservator tank; and the breather vessel being sealed to prevent any air exchange between the interior of the breather vessel and the atmosphere; a) installing the breather vessel externally in relation to a conservator tank and arranging the breather vessel in sealed fluid communication with the interior of the conservator tank; b) operating the breather vessel to allow air movement between the interior of the conservator tank and the interior of the breather vessel without any air exchange between the interior of the breather vessel and the atmosphere.

Preferably, the conservator tank is an existing conservator tank and the step b) comprises retrofitting the breather vessel to said existing conservator tank.

Features of the first aspect of the invention can be incorporated into the second aspect of the invention as appropriate and vice versa. The invention provides a transformer breather arrangement for oil filled transformers and a method of operating a transformer breather arrangement for oil filled transformers as defined in the appended claims.

Detailed Description of the Invention

The invention will now be described with reference to the accompanying drawings, which C\I show, by way of example only, an embodiment of the invention. In the drawings: a) Figure 1 is a schematic elevation of a transformer breather arrangement in accordance with the invention.

LO

CJ Referring to Figure 1, a transformer breather arrangement of the invention is indicated generally by reference numeral 1. The transformer breather arrangement 1 comprises a breather vessel 3 adapted installed externally in relation to a transformer conservator tank 5 of a transformer 7. The breather vessel is arranged in sealed fluid communication with the interior of the conservator tank 5. The breather vessel 3 is adapted to capture and store air received from the interior of the conservator tank 5. The breather vessel 3 is sealed to prevent any air exchange between the interior of the breather vessel 3 and the atmosphere.

Although not indicated in the drawings, the breather vessel 3 may be arranged to expand upon receiving air from the conservator tank 5. The expandable breather vessel 3 provides a visual indication of air movement between the conservator tank 5 and the breather vessel 3. The breather vessel 3 may be free from an enclosure.

The breather vessel 3 may be provided in the form of bag, but the invention is not in any way limited thereto.

The breather vessel 3 may have flexible walls.

The walls of the breather vessel 3, or at least one or more portions thereof, may be made from an elastomeric material so as to enable greater degree of expansion of the breather vessel 3 in order to accommodate greater quantity of air exhaled from the conservator tank 5.

The interior of the breather vessel 3 is sealed from the atmosphere to prevent any air retained in the interior of the breather vessel 3 from escaping into the atmosphere. This also prevents any moisture ingress from the atmosphere into the breather vessel 3 and the conservator tank 5 and ensures that the conservator tank 5 breathes dry air at all times. The interior of the breather vessel 3 is preferably sealed from the atmosphere at all times.

The transformer breather arrangement 1 comprises a fluid manifold 9 for connecting the respective interiors of the breather vessel 3 and the conservator tank 5 and providing the sealed fluid communication with the interior of the conservator tank 5. The breather vessel 3 has a port 11 between its exterior and its interior and the fluid manifold 9 is coupled to the breather vessel 3 via the port 11 so that air exchange between the interior of the breather vessel 3 and the fluid manifold 9 takes place directly via the port.

As the transformer oil heats or cools, air exchange takes place between the interior of the conservator tank 5 and the interior of the breather vessel 3. Oil expansion displaces air from the conservator tank 5 into the fluid manifold 9, from which the air is received in the breather vessel 3 via the port 11. Oil cooling and contraction causes a reverse process, i.e. air is sucked back from the breather vessel 3 into the conservator tank 5 via the port 11 and the fluid manifold 9. During this process, due to the breather vessel 3 being isolated from the atmosphere at all times, no air exchange occurs between the interior of the breather vessel 3 and the atmosphere.

The breather vessel 3 inflates of deflates accordingly as it receives or releases air. The inflation preferably initially occurs due to the flexibility of the material of the breather vessel 3, i.e. the incoming air inflates previously collapsed walls of the breather vessel 3.

This occurs until a predetermined amount of air has entered the breather vessel 3. Any further increase in the quantity of air inside the breather vessel 3 is accommodated by the expanding property of the breather vessel 3. The expanding property may be achieved by making the breather vessel 3 or at least a portion thereof from an elastomeric material to allow the breather vessel 3 to expand and contract in accordance with the quantity of air received in the interior of the breather vessel 3. Alternatively or additionally, an expansion arrangement (not shown) may be built into the breather vessel 3, such as, for example, a bellows-type expansion arrangement or an elastomeric membrane. The expansion arrangement accommodates more of the incoming air and keeps the pressure within the breather vessel 3 at the same level, or at least within allowed predetermined minimal fluctuations. Other expansion arrangements are envisaged as will be apparent to the person skilled in the art.

It will be appreciated that in other embodiments the breather vessel 3 may be rigid.

The interior of the breather vessel 3 is free from a hygroscopic substance. The breather vessel 3 of the invention eliminates the need to re-place the hygroscopic substance and thus reduces maintenance costs and potential downtime.

The breather vessel 3 may be provided in the form of a bag.

The transformer breather arrangement 1 may comprise a container 15 with a hygroscopic substance, the container 15 being provided along the fluid manifold 9 upstream of the breather vessel 3 and having at least a pair of ports, a first port 17 for fluid exchange between the container 15 and the conservator tank 5 and a second port 19 for fluid exchange between the container 15 and the interior of the breather vessel 3. The hygroscopic substance may be any suitable hygroscopic substance, such as, for example, but not limited thereto, silica gel. Thus, in use, prior to being received in the breather vessel 3, air exhaled from the conservator tank 5 passes through the container 15 and through the hygroscopic substance. Thus, the container 15 serves as a backup safety device in case the breather vessel 3 fails. In case of failure of the breather vessel 3, the container 15 will continue to maintain air movement to and from the conservator tank 5, whilst filtering any moisture which may be contained in the air being inhaled by the conservator tank 5. As long as the breather vessel 3 is working correctly, the hygroscopic substance will never need to be replaced. If the breather vessel 3 fails, the hygroscopic substance will change colour due to contact with moisture from the atmosphere and provide a visual indication of failure within the transformer breather arrangement 1. The container 15 is preferably configured such that at least a portion of the hygroscopic substance within the container is visible from the outside. This can be achieved by making the container 15 transparent or providing a window in the container 15.

The transformer breather arrangement 1 may be provided with a bi-directional pressure relief valve 21 installed in the fluid manifold 9 upstream of the breather vessel 3 to accommodate unexpected pressure spikes. The bi-directional pressure relief valve 21 may be installed in the fluid manifold 9 between the breather vessel 3 and the container 15. The breather vessel 3 of the invention replaces the prior art breather canister that contains hygroscopic substance and exchanges air with atmosphere. The breather vessel 3 can be retrofitted on existing conservator tanks.

The transformer breather arrangement 1 may comprise a conservator tank monitor 23 adapted to monitor conservator tank oil level, temperature and moisture. The monitor 23 is preferably adapted to indicate breather vessel 3 failure based on the conservator tank oil level, temperature and moisture readings and alarm this condition. The monitor 23 may be located on and/or in the conservator tank 5.

The fluid manifold 9 may comprise a flexible braided hose.

The breather vessel 3 may have a capacity of 3001 to cater for every 50001 of oil in the conservator tank 5. Two or more breather vessels 3 may be provided connected in parallel to accommodate greater than 50001 of transformer oil.

It will be appreciated by those skilled in the art that variations and modifications can be made without departing from the scope of the invention as defined in the appended claims.

Claims

CLAIMS: 1. A transformer breather arrangement for oil filled transformers, the transformer breather arrangement comprising: a breather vessel adapted to be installed externally in relation to a transformer conservator tank of a transformer; the breather vessel being adapted to be arranged in sealed fluid communication with the interior of the conservator tank; the breather vessel being adapted to capture and store air received from the interior of the conservator tank; wherein the breather vessel is sealed to prevent any air exchange between the interior of the breather vessel and the atmosphere; wherein the transformer breather arrangement comprises a container with a hygroscopic substance, the container being provided along the fluid manifold upstream of the breather vessel and having at least a pair of ports, a first port for fluid exchange between the container and the conservator tank and a second port for fluid exchange between the container and the interior of the breather vessel, wherein in use, prior to being a) received in the breather vessel, air exhaled from the conservator tank passes through the container and through the hygroscopic substance; and 14)20 wherein the container is configured such that at least a portion of the hygroscopic CJ substance within the container is visible from the outside.
2. A transformer breather arrangement of claim 1, wherein the breather vessel is expandable.
3. A transformer breather arrangement of claim 2, wherein the breather vessel is adapted to expand upon receiving air from the conservator tank.
4. A transformer breather arrangement of any preceding claim, wherein the breather vessel is provided in the form of bag.
5. A transformer breather arrangement of claim 4, wherein the breather vessel has flexible walls.
6. A transformer breather arrangement of any preceding claim, wherein at least one or more portions of the walls of the breather vessel are made from an elastomeric material.
7. A transformer breather arrangement of any preceding claim, wherein an expansion arrangement is built into the breather vessel.
8. A transformer breather arrangement of any preceding claim, wherein the interior of the breather vessel is sealed from the atmosphere at all times.
9. A transformer breather arrangement of any preceding claim, wherein the transformer breather arrangement comprises a fluid manifold for connecting the respective interiors of the breather vessel and the conservator tank and providing the sealed fluid communication with the interior of the conservator tank.
10. A transformer breather arrangement of claim 9, wherein the breather vessel has a port between its exterior and its interior and the fluid manifold is coupled to the breather vessel via the port so that air exchange between the interior of the breather vessel and the fluid O manifold takes place directly via the port. C\Ia)
11. A transformer breather arrangement of any preceding claim, wherein the interior of the breather vessel is free from a hygroscopic substance. In20 (\I
12. A method of operating a transformer breather arrangement for oil filled transformers, the method comprising the steps of: a) providing a transformer breather arrangement comprising: a breather vessel adapted to be installed externally in relation to a transformer conservator tank; the breather vessel being adapted to be arranged in sealed fluid communication with the interior of the conservator tank; the breather vessel being adapted to capture and store air received from the interior of the conservator tank; and the breather vessel being sealed to prevent any air exchange between the interior of the breather vessel and the atmosphere; a container with a hygroscopic substance, the container being provided along the fluid manifold upstream of the breather vessel and having at least a pair of ports, a first port for fluid exchange between the container and the conservator tank and a second port for fluid exchange between the container and the interior of the breather vessel, wherein in use, prior to being received in the breather vessel, air exhaled from the conservator tank passes through the container and through the hygroscopic substance; the container being configured such that at least a portion of the hygroscopic substance within the container is visible from the outside b) installing the breather vessel externally in relation to a conservator tank and arranging the breather vessel in sealed fluid communication with the interior of the conservator tank; c) operating the breather vessel to allow air movement between the interior of the conservator tank and the interior of the breather vessel without any air exchange between the interior of the breather vessel and the atmosphere.
13. A method of claim 12, wherein the conservator tank is an existing conservator tank and the step b) comprises retrofitting the breather vessel to said existing conservator tank.