ES2310021T3 - BUCHHOLZ RELAY OF IMPROVED GAS ACCUMULATION. - Google Patents

Abstract

A gas-accumulation Buchholz relay, which comprises, to be immersed in an oil bath, a supporting frame (23) for magnetic switches (27) for closing circuits and at least one movable device (28,29) of the float type for actuating the switches. The relay is characterized in that the float (30) is of the lever type with a rotation axis which is fixed to the frame (23) and is operatively connected to a magnet holder which acts as a counterweight. The float (30) is articulated in its rotation with respect to the magnet holder through a given angle. <IMAGE>

Description

Buchholz gas accumulation relay improved.

The invention relates to a Buchholz relay of Improved gas accumulation.

It is well known that in transformers submerged in oil it is necessary to install relays of this type of so that they detect and indicate both presence and generation Of gas.

The presence of gas in a transformer is a fact always associated with a malfunction, due to the gas that originates from the outside through the pumps of circulation or is produced by the breakdown of insulators liquids or solids inside the transformer.

This decomposition of the insulators is caused by overheating or the appearance of arcs electrical

The Buchholz relay must be installed in the transformer under the expansion vessel, commonly known as  conservative, and is filled with oil during operation normal.

Constructively, this type of relay is constituted by a body that is obtained from cast aluminum alloy within which a support frame for at least one mobile device is arranged; The mobile device comprises a float for operating at least one magnetic switch of a type known per se enclosed in a bulb.

Actually, Buchholz relays are provided normally from a top float that activates and deactivates a alarm circuit and with a bottom float that is connected directly to a disconnection circuit.

If gas forms inside the transformer, it tends to escape upwards, flowing into the expansion vessel and thus gradually accumulating inside the relay.

This accumulation of gas inside the body of the relay causes a drop in the oil level that is detected by the upper float, which drives the switch accordingly magnetic with which it is associated and by means of which it closes The alarm circuit

If gas accumulation continues, within Relay the oil level undergoes an additional drop that is detected by the bottom float, which is connected directly to the circuit for disconnecting the transformer from the line energy supply.

On the other hand, all Buchholz relays have an additional protection that is able to detect strong oil currents generated, for example, by short circuits.

This protection is constituted by a properly fitted skirt that is sensitive to the flow rate of the oil current and is also connected to the circuit to disconnect the transformer from the power supply.

This type of relay is also used to indicate any oil leakage from the transformer tank, because in this case also lowers the general oil level and consequently The floats descend.

This descent of the floats determines the external alarm activation and / or disconnection circuits connected to them.

A Buchholz relay of this type is known that it has all the features of the preamble of the claim 1, for example, of document BE678625A.

In addition, it is extremely important that the relays are able to function properly in the presence of vibrations caused by seismic activity.

For this reason, all Buchholz relays are submitted, before being marketed, to experimental tests during which they are placed on a stirring table and, by means of a suitable tool, the test operator records the accelerations with which the alarm is closed and the disconnection circuits; these accelerations are greater than values established by the standards and / or by the specifications of the users of the relays.

However, unfortunately during startup of the transformer the relay is commonly affected by an impact due to handling operations and, due to vibrations generated by this impact, the floats close incorrectly the alarm and / or the disconnection circuit.

Obviously this causes a huge and useless wasted time to start over with the maneuvers to Start the transformer.

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The purpose of the present invention is to provide a Buchholz relay that is sensitive to variations in the level of the oil and insensitive to the appearance of vibrations due to seismic activities or maneuvers to start the transformer, acting properly on the alarm and / or the circuits of disconnection

Within the scope of this purpose, an object important of the present invention is to provide a Buchholz relay that ensure good characteristics in terms of intervention insured

Another important object is to provide a relay Buchholz whose configuration is simpler than that of the types conventional.

Another object of the present invention is to provide a Buchholz relay whose assembly and maintenance are simpler and faster to perform with respect to conventional relays.

This purpose, these objects and others that will be evident from now on are achieved by a relay Buchholz gas accumulation, which comprises, being submerged in a oil bath, a support frame for magnetic switches to close circuits and at least one type mobile device float for operating said switches, characterized in that said float is lever type with a rotation axis that is fixed to said frame and is operatively connected to a magnet holder that acts as a counterweight, said float being articulated in its rotation with respect to said magnet holder along of a given angle.

More features and advantages of this invention will be apparent from the following description Details of a preferred embodiment, illustrated by way of example non-limiting in the attached drawings, in which:

Figure 1 is a partially sectioned view of a transformer provided with a Buchholz relay according to the present invention;

Figure 2 is a front view of a relay Buchholz according to the invention;

Figure 3 is a perspective view of the internal mechanism of the relay of Figure 2;

Figure 4 is a perspective view in exploded view of the mechanism shown in Figure 3;

Figure 5 is a perspective view of the details of the relay mechanism of Figure 2;

Figure 6 is a perspective view in exploded view of the details shown in Figure 5.

With reference to the previous figures, an oil-filled transformer is generally designated by reference number 10 and has a tank with radiators 11 on which an expansion vessel 12 of a type known per se is connected.

The transformer 10 is conventional and the Figure 1 illustrates high voltage insulators 13, an oil trap 14 and a thermometer 15 to detect the oil temperature.

The transformer 10 is provided with a relay Buchholz, according to the invention, which is generally designated by the reference number 16 and is integrated between the transformer and the expansion vessel 12.

The relay 16 is constituted by a body 17 that It is preferably airtight and is made of aluminum alloy cast and in which inspection gates 18 are defined, preferably made of tempered glass or very plastics resistant, provided with graduated scales 19.

At the top, relay 16 is provided of a lid 20 from which a tap 21 protrudes to discharge the gas and a pneumatic test valve 22.

The frame 23 is arranged inside the relay 16, It is made of plastics, and is provided, in a higher area, with through holes 24 for fitting with the cover 20 by means of fixing screws not shown in the previous figures For simplicity.

Frame 23 has, in this configuration, a mainly longitudinal structure that includes two uprights 25 in which there are seats 26 to accommodate magnetic switches 27.

Each of said switches 27 is conventional and has, within a bulb, a magnet and contacts electrical, not shown in the figures, which are connected directly to an alarm circuit and / or a circuit disconnection

A top mobile device 28 and a equivalent lower mobile device 29 are fixed to the frame 2. 3.

Each of the mobile devices 28 and 29 it comprises a lever-type float 30, which has a structure substantially ovoid in which there are flat areas 31 and from which an arm 32 protruding from a longitudinal band of the float 30.

First and second elastic curved fins 34a and 34b protrude from said arm 32 and together define a semi-tubular profile 33.

In particular, the first fin 34a is shorter that the second fin 34b, to form, together with the second fin and at each end, a seat 35 covering a reduced angle in cross section.

A pivot 36 is inserted in the profile semi-tubular 33 and is appropriately shaped complementary to fins 34a and 34b.

A radial extension 36a protrudes in each end of said pivot 36, which constitutes the axis of rotation for the float 30; a magnet holder 37 is associated with the extension radial, parallel to pivot 36, has a configuration substantially tubular and is provided, at its two ends, with elastic teeth 38.

The pivot 36 is adapted to be inserted in the semi-tubular profile 33 between the fins 34a and 34b, so that each extension 36a is arranged in the seat 35.

A counterweight 39 can be inserted into the magnet holder 37 and has a cylindrical structure; said counterweight has to be inserted in a central position and in contact, in its two ends, with a first magnet and a second magnet that are designated respectively by reference numbers 40 and 41 and have preferably a structure similar to a tablet.

The counterweight 39 is preferably made of brass.

The first and second magnets 40 and 41 and said counterweight 39 are retained in the holder 37 by means of the pressure retention provided by teeth 38 and optionally by means of the presence of a suitable adhesive.

In the uprights 25 of the frame 23 are you provide first and second guides 42 and 43, respectively in the upper and middle parts of the frame 23; shape ends complementary to pivot 36 of each of the devices Top and bottom mobiles 28 and 29 can slide along these guides.

Each of guides 42 and 43 has, in the part from the innermost end of its extension, a seat 44 adapted to house the pivot end 36 of each of the devices mobile 28 and 29.

Therefore, mobile devices are mounted in frame 23 by pressurized action after moving along of guides 42 or 43 with pivot ends 36 for insertion and consequent lock on seats 44.

The Buchholz 16 relay is also provided with a element similar to a rod 45 that is associated with one of the uprights 25 of the frame 23 and whose upper end is accessible to a user by means of an adapted spring-operated push button, which is not shown in the figures previously cited by simplicity

An upper lever 46 and a lower lever 47 are associated with the rod-like element 45; every lever is L-shaped and has, at its hitch end, a appendix 48 which is monolithic with a ring 49 inside which inserts said rod-like element 45 substantially without slack

Each lever 46 and 47 can slide along of the rod-like element 45 along the path determined respectively by a top guide 50 and by a guide bottom 51, which are both formed in the post 25; the Appendices 48 of levers 46 and 47 move along the guides

The levers are required by relay 16 respectively to mechanically test the alarm circuit, which is associated with the upper mobile device 28, and the disconnection circuit, which is associated with the mobile device lower 29.

By actuating the element similar to a rod 45, that the said two levers 46 and 47 are associated, is possible, in fact, push down the floats 30 to check mechanically closing the alarm circuits and disconnection

The relay 16 also has a skirt 52, of a type known per se , which is associated with the lower frame 23 of the lower mobile device 29 and is adapted to detect any presence of strong oil currents within the relay 16.

The operation of the Buchholz 16 relay described with the present invention it is extremely simple, since the Lever type 30 floats of the upper e mobile devices lower 28 and 29 follow the oil level, rising and falling in function of that level.

In particular, each float 30, following the oil level variations, rotates with respect to pivot 36, but by coupling the two extensions 36a in the seats 35 formed in the semi-tubular profile 33 by the fins 34a and 34b is partially articulated with respect to the holder 37, is say, it has a certain slack.

Said clearance is determined by the width of the angle that float 30 can move without transmitting its movement to the two extensions 36a and consequently to the magnet holder 37.

When contact is established between the float 30 of a mobile device 28 and 29 and the magnet holder 37 corresponding, the magnet holder, rigidly following the float 30 in its rotation, it moves in fact with respect to the frame 23 and so they do the first and second magnets 40 and 41 with him.

The movement of the first and second magnets 40 and 41 determines an interaction with the magnets contained in the bulb of switches 27, causing, due to consequent movements between the electrical contacts enclosed in the bulb, the closure of the alarm or disconnection circuit connected to them.

In this way, the maximum extent of the clearance that may occur between lever type float 30 and the corresponding holder 37 determines the degree of sensitivity from relay 16 to vibrations.

It is clear that the adjustment of this angle should studied carefully to make relay 16 conveniently immune to vibrations caused by operations to boot the transformer 10 and the vibrations generated by activity seismic or by other phenomena.

In practice it has been observed that this invention widely achieves the purpose and all objects pretended.

An important advantage has indeed been achieved with the present invention because an accumulation relay has been devised  Buchholz type gas that is able to ensure different sensitivity depending on the speed of the oil flow at which is subject, thus ensuring greater reliability of functioning.

Another advantage is achieved by the present invention. because a Buchholz relay has been provided that has a configuration Simple structural

Another important advantage is achieved by considering that the present invention provides a relay whose assembly can easily achieved more easily and quickly than in types conventional.

The materials used, provided they are compatible with the use to which they are subject, they can also be Any according to the requirements.

Where the technical characteristics mentioned in any claim they are followed by reference signs,  those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and, by consequently, such reference signs have no effect limiter on the interpretation of each element identified to by way of example by such reference signs.

Claims (6)

1. A Buchholz gas accumulation relay (16), comprising, being immersed in an oil bath, magnetic switches (27) to close circuits and at least one mobile device (28, 29) of float type (30) for activating said switches (27), characterized in that the relay (16) is provided with a support frame (23) immersed in said oil bath for said magnetic switches (27) and at least one of said mobile devices (28, 29) , said float (30) is of the lever type with a rotation axis (36) that is fixed to said frame (23) and is operatively connected to a magnet holder (37) that acts as a counterweight (39), said float (30) being ) articulated in its rotation with respect to said magnet holder (37) along a given angle. The relay (16) according to claim 1, characterized in that said float (30) protrudes an arm (32) and is provided with a semi-tubular profile (33) in which a pivot (36) can be coupled, said pivot being (36) fixed to said frame (23) by means of its ends and being rigidly associated with said magnet holder (37). 3. The relay (16) according to claim 2, characterized in that said semi-tubular profile (33) is constituted by two arc-like fins (34a, 34b) that form a seat that is shaped in a complementary manner to said pivot (36), one of said fins (34a, 34b) being shorter than the other to form at least one seat (35) whose angle in cross section is reduced with respect to the remaining part of the semi-tubular profile (33), at least one extension (36a ) projecting radially from said pivot (36) to associate said pivot (36) and said magnet holder (37), said pivot (36) being inserted into said semi-tubular profile (33) until said extension (36a) is located in said seat ( 35). The relay (16) according to claim 3, characterized in that said float (30) is articulated with respect to said magnet holder (37) an angle that is determined by the difference between the angle covered by said seat (35) formed in the semi-tubular profile (33) and the width of said extension (36a). 5. The relay (16) according to claim 1, characterized in that said magnet holder (37) has a tubular extension internally containing a counterweight (39) and, at least at one end, a magnet (40, 41) for operating a switch corresponding of said switches (27). The relay (16) according to claim 2, characterized in that said frame (23) provides mutually opposite guides (42, 43) for sliding the ends of said pivot (36), each guide ending (42, 43 ) with a seat (44) for the pressure insertion of the end of said pivot (36).