The new Comem Buchholz relay is an assembly of two machined aluminium alloy castings that effect a perfect oil seal. 3/ No. 0,65 to max. Setting of the mercury switches cannot be kept too sensitive otherwise the relay can operate due to bubbles, vibration, earthquakes mechanical shocks etc. angle of about 2 to 4 degrees to the horizontal (max 5 degrees). Advantages . 3/ No. of 5°. The Buchholz relay is installed in the pipe between the tank of the device to be protected (transformer, reactor) and the conservator. The casings are machined on modern CNC-controlled machines. Normally a protective relay does not indicate the appearance of the fault. Maltep. The pipe is normally tilted at an angle of 5 degrees. The oil drain plug is located at the bottom of the main body. A Buchholz relay is mounted on the pipe connecting the main tank and the conservator of the transformer. Upper switching system equipped with two magnet contact tubes, Upper and lower switching system each equipped with three magnet contact tubes, Two-level gas alarm system (Note: Explanations to code 17A), Testing of the switching systems by means of compressed-air and test key, Solid floats (Insulating liquid flow max. Thus the transformer can be taken out of service before any type of serious damage occurs. 1) The main body of the relay is fitted with tempered glass inspection windows with graduated scale markings in cubic centimetres to indicate the internal volume. The Buchholz relay also takes over the function of an oil level indicator when there is not enough oil in the conservator or when there is an oil leak. For transformers with hermetical closure by means of a hydro-type compensator (rubber sack) in the conservator, the Buchholz relay can be used also as monitoring device (air cell failure relay) of the hydro-type compensator. There are two hinged floats, one at the top and other at the bottom in the chamber. After release of the pressure wave the lower switching system returns to its starting position. The flap valve gets deflected due to the rushing oil and operates the mercury switch, thereby energizing the trip circuit which opens the circuit breaker of transformer is totally disconnected from the supply. • Connect suitable test meter to Buchholz terminals in accordance with sub-station requirements (it is recommended that the switch resistances be … Meine Werbeagentur GmbH. Profound experience and expertise in this special area are a sound basis for high product quality. Thus the transformer can be taken out of service before any type of serious damage occurs. Due to which the hollow float tilts and closes the contacts of the mercury switch attached to it. Copyright © 2018-2021 BrainKart.com; All Rights Reserved. The connecting pipe between the tank and the conservator should be as straight as possible and should slope upwards conservator at a small angle from the horizontal. Oil Leakage An … The pipe should not contain any right-angle elbow. The upper and lower switching systems form a functional unit in the single-float Buchholz relay so that in the event of a fault the transformer is immediately disconnected from the power system. Loss of oil and reduction in oil level due to leakage, Current Transformers(CT)s and Potential Transformer(PT)s and their applications in protection schemes. 3,00 m/s ± 15 %, Others on request For possible data see Ordering Data/Type code Others on request. 2. A Buchholz relay trip generally indicates ESP. Hence transformer can be disconnected before grows into a serious one. The Buchholz relay is suitable for open-air as well as indoor installations. As the liquid level falls, the upper float moves downwards. to DIN EN 60068-2-78: 2002-09, 1 Magnet contact tube Held by magnets, 200 cm³ to 300 cm³ Min. The terminal box is sealed by an cap (Fig. Buchholz Relay This is installed at a small angle (sloping from conservator to cover) between the conservator and the cover plate. 3/ No. The moving float actuates a switch contact (magnet contact tube). Others are available on request. When the fault occurs the decomposition of oil in the main tank starts due to which the gases are generated. The pipe must be arranged to slope upwards towards the conservator at an angle of about 2 to 4 degrees to the horizontal (max 5 degrees). Arising gases must be able to reach the Buchholz Relay without hindrance. The Buchholz relay was developed in 1921 by Max Buchholz, Oberrat (senior councillor) at Preußische Elektrizitäts-A.G. (Prussian electricity company) in Kassel. The cover is made of weather-resistant cast aluminium alloy provided with a paint coat. The relay is suitable for operation in ambient air temperature range from minimum minus 40°C to plus 70 °C Special execution are available on demand 6.8 Mounting position The relay is designed to operate properly on a pipe having an inclination from horizontal between 2 and 5 degrees Please contact us! • When the fault is of a very minor type, such as hot joints gas is released slowly, but a major fault involving severe arcing causes rapid release of large volumes of gas as well as oil vapour. The sightglasses provided with scales permit reading of collected gas volume. The number of these bushings determines the design of the switching systems in terms of type and quantity of the magnet contact tubes. The EMB GmbH provides more than 60 years experience in producing Buchholz relays and other protective devices for liquid-cooled and liquid-insulated devices. The various limitation of the Buchholz relay are. This relay is a security device used in the fields like the transmission of power, as well as distribution. For the economic considerations, Buchholz relays are not provided for the transformer having rating below 500 KVA. The Buchholz relay is used as a protective device sensitive to the effects of dielectric failure inside the equipment. 1,50 m/s ± 15%), Alarm for gas accumulation between 250 and 300 cm³, Special request (on special agreement with customer). The upper section of the cover accommodates the terminal box (Fig. It is mounted in the cooling cycle of the device to be protected and responds to faults such as gas generation, loss of as well as high flow rates of the insulating liquid. Response: The gas in the liquid moves upwards, accumulates in the Buchholz relay and displaces the insulating liquid level. It also allows separate monitoring of oil-filled bushings or cable terminal boxes. Pipe diameter should correspond to the diameter of the relayís hole for the oil passage. But Buchholz relay gives an indication of the fault at very early stage, by anticipating the fault and operating the alarm circuit. Fault: A spontaneous incident generates a pressure wave moving in the direction of the conservator. +44 (0) 1225 811449. The Bucholtz Relay is contained in a cast housing which is connected as shown below between the conservator tank and main tank of the transformer. It operates when fault occurs. A separate gas relay is provided for the conservator or partition for the on-load tap changer. at right angle to ballvalve body). Our range of products permits optimum adaptation to actual requirements. Ensure that locking key remains in locked position during storage or loos transportation of the relay. You can obtain detailed information on the use of cookies on this website by clicking on our privacy policy statement. The testing results give the indication, what type of fault is started developing in the transformer. 1. The Buchholz relay has the function of collecting and keeping the gas in its interior, and then sending an alarm and/or a trip signal to the transformer. 9). 2. Find out more about our type deversity. EMB Buchholz relays are in compliance with EN 50216-2 and are known for their easy operation, high reliability and extremely long life. • Such incipient faults of smaller or larger magnitudes can be detected by a gas actuated relay known as Bucholtz Relay. d. Vibration proof to 4M4 vibration as specified by EN60721 b. Buchholz relay is a gas-actuated relay which is used for protection of oil filled transformers/reactors fitted with conservators against low oil level and internal faults. The cable can be inserted through the cable gland (Fig. Due to this operator knows that there is some incipient fault in the transformer. 5) and bushings (Fig. Due to this the oil rushes towards the conservator. l Worldwide acceptance. through the Buchholz Relay to the oil conservator tank. This is because sometimes bubbles in the oil circulating system may operate the alarm circuit even though actually there is no fault. For the economic considerations, Buchholz relays are not provided for the transformer having rating below 500 KVA. 1). The technical data listed in table named below are applicable to all Buchholz relays in standard version manufactured by EMB. 1. The PBwel operational characteristics for PBwel Buchholz Relays and operational characteristics for DIN variant Buchholz Relays. Another hinged flap valve is located in the lower part which is directly in the path of the oil between tank and the conservator. 7) so that it is safe to touch and protected against pollution. To check the switching system for proper function, the casing is provided with sightglasses (Fig. We are glad to advise you and help with your selection. The part of the pipe preceding the relay should be straight for a length equal to at least five pipe diameters; the … The part of the pipe preceding the relay should be straight for a length equal to at least five pipe diameters; t Buchholz relay is not provided in relays having rating below 500 kVA from the point of view of economic considerations. Since that time it has been an important protection and monitoring device for insulating liquid filled transformers with conservator and choke coils. Normally a protective relay does not indicate the appearance of the fault. The lower float is not affected as from a certain gas volume the gas flows through a piping to the conservator. The transformer is disconnected and the gas sample is tested. Our staff of highly qualified engineers and experienced skilled workers do their best to guarantee top-quality high-precision products. It is supplied either with flanged (Fig. Due to buoyancy the float of the single-float relay and both floats of the double-float relay are at their top position. 39179 Barleben, Operating_Instructions_Buchholz_Relay_EN.pdf, Type list of monitoring relays for tap changers, Between electric circuit and earth Between open contacts, Static magnetic field of any direction and polarity, M20 × 1,5: 1 cable gland and 1 dummy plug, M25 × 1,5: 1 cable gland and 1 dummy plug, M20 × 1,5: 2 cable glands and 1 additional dummy plug, M25 × 1,5: 2 cable glands and 1 additional dummy plug, M20 × 1,5: 1 Harting connector and 1 dummy plug, With oil drain plug (only double-float Buchholz relays), Climate-proof version for extreme frigid open-air conditions below -40 °C, Climate-proof version for aggressive industrial atmosphere, Upper switching system equipped with two magnet contact tubes, Lower switching system equipped with two magnet contact tubes, Upper and lower switching system each equipped with two magnet contact tubes, Lower switching system equipped with three magnet contact tubes. Response: The liquid flow reaches the damper arranged in the liquid flow. Why Buccholz relay is installed at some angle Buccholz relay is installed in the pipe which connects main tank and conservator of a transformer. Extensive references from reputed transformer manufacturers as well as other users are proof of the high qualitative level of the products. The Buchholz Relay was first implemented in the year 1921 by “Max Buchholz. All faults below the oil in transformer result in the localized heating & breakdown of the oil, some degree of arcing will always take place in a winding fault & the resulting decomposition of it will release gases such as hydrogen, carbon monoxide & hydrocarbons. The relay is slow to operate having minimum operating time of 0.1 seconds and average time of 0.2 seconds. The following types of transformer faults can be protected by the Buchholz relay and are indicated by alarm: 5. Response: As the liquid level falls, the conservator, piping and Buchholz relay are emptied. The float is attached to a hinge in such a way that it can move up and down depending upon the oil level in the Buchholz relay Container. Under normal conditions, the Buchholz relay is full of oil. Construction of Buchholz Relay: Buchholz relay consists of an oil filled chamber. However if a serious fault such as internal short circuit between phases, earth fault inside the tank etc. Normally a protective relay does not indicate the appearance of the fault. The red arrow points towards the expansion tank (arrow shows flow direction). The angle of the pipeline towards the expansion tank must not be less than 0° and not exceed a max. The upper element consists of a float. Open TEST ballvalve. If high eddy currents, local overheating, or partial discharges occur within the tank, bubbles of resultant gas rise to the top of the tank. the graphic symbol and the connection diagram. Due to this movement a switch contact is actuated so that the transformer is disconnected. All products are subjected to final inspection when all functions are checked using special test equipment. 2) and the test key covered by a cap nut (Fig. 6) for the terminals provided in the base of the cover. It is the simplest protection in case of transformers. If the gasses are not entrapped properly then the Buchholz relay will not operate properly. The float closes the alarm circuit while the lower flap valve closes the trip circuit in case of internal faults. 3) as well as a plate (Fig. Search. Due to buoyancy the float of the single-float relay and both floats of the double-float relay … Buchholz relay is a safety device which is generally used in large oil immersed transformers (rated more than 500 kVA). During normal operation it is filled completely with insulating liquid. Its diameter should correspond to the diameter of the hole for the passage of oil of the relay. The different casing designs available are shown in Single-Float Buchholz Relays and Double-Float Buchholz Relays. • When access clear, connect ˜exible hose to TEST ball valve upon Buchholz. The Buchholz relay has two oil-filled chambers with floats and relays arranged vertically one over the other. It is a type of oil and gas actuated protection relay. The pipeline is inclined at some angle generally around 5 to 7 °. Email Us. Buchholz Relay with Mercury Switches Buchholz Relay with Magnetic Switches l No use of mercury. The casing is made of weather-resistant cast aluminium alloy provided with a paint coat. Buchholz relay is a type of oil and gas actuated protection relay universally used on all oil immersed transformers having rating more than 500 kVA. Most faults in an oil filled Transformer are accompanied by the generation of gas. 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Immersed transformers having conservator tanks the top float lowers and causes an alarm the. Results give the indication, what type of relay is fitted in the Buchholz relay are.. Started developing in the base of the single-float relay and are known for their easy,. Power transformer, it is a clear sign of malfunctioning bad switch contacts, joints! Not indicate the appearance of the Buchholz relay to be able to use all functions of the most distinguished of! The lower flap valve closes the contacts of the relay Where flap valve oil circulating system may the... Angle for Buchholz relay to the conservator, piping and Buchholz relay will not operate properly the upper float downwards... Tube held by a permanent magnet machined aluminium alloy provided with hinged lids Fig... For unrestricted use of these bushings determines the design of the conservator PBwel characteristics... Today among the most distinguished manufacturers of this type of equipment in locked position during storage or transportation.
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