KR100348704B1 - A fuse-bushing for protecting a transfomer from over power - Google Patents

Abstract

The present invention relates to a fuse overload protection fuse bushing in which a fuse is designed in series in which a rating and an overload are calculated inside a bushing installed at the power inlet and outlet parts of the primary and secondary sides of the transformer. The car inlet is provided with a bushing (lead insulator) for conductor and conductor insulation to transport the current supplied from the outside into the transformer, and this conventional bushing only performs insulation function from the conductive path and external ground. However, according to the fuse bushing according to the present invention, the rated capacity of the transformer in series with the conductor 120 in the inner insulation pipe 111 of the bushing housing 110 of each of the primary side and secondary side of the transformer By installing the overload protection fuse 130, the melted element 302a of the fuse 130 during the overload is melted by Joule heat of J = I ² R while the external incoming power and Disconnecting the transformer from the output side load to cut off the overload within a certain time, thereby protecting the transformer has the effect of preventing the power accident in advance.

Description

Fuse-bushing for protecting a transfomer from over power

The present invention relates to a fuse bushing for protecting a transformer overload, and more specifically, a fuse designed to calculate a rating and an overload inside a bushing installed at a power inlet and outlet part of a primary side and a secondary side of a transformer in series. An integrated fuse overload protection fuse bushing.

Conventional bushings (or so-called insulators) are installed on the primary and secondary sides of a transformer to draw and draw current from the exterior of the power equipment or from the interior to the exterior, insulated from the enclosure. One of the most important components for the protection of circuits, but so far has been used only for isolation purposes.

Countries around the world set independent standards for bushings to define ratings, basic characteristics, test methods and mounting methods. These bushings are divided into insulation bushings, single bushings, inflow bushings and condenser bushings. It is not. FIG. 1 illustrates a high pressure magnetic material and a composite material bushing 10 which are currently used in general, and a conductor 11 is inserted in the inside and a plurality of disc protrusions 12 are formed on the outer surface.

Generally, electrical accidents expected in transformers include all or partial shorts of the windings, ground faults of the windings, or mixing of the primary and secondary windings, disconnection, etc., intrusion of lightning surges, external short circuits or overloads on the secondary side. The back can be a direct cause of accidents. Due to such electrical accidents, hundreds of transformer accidents occur every year, causing damage to human resources and property.In order to protect against such accidents, limited overload characteristics of the transformer itself, relay operation from outside, and temperature rise inside the transformer are prevented. External cut-off by prevention switch (CSP), and short-circuit cut-off switch (COS: Cut Off Switch) in the case of high voltage pole transformer.

In the conventional equipment for transformer protection, a bank capacity of 5 MVA special high-voltage transformer is installed in the electrical installation standard to automatically disconnect from the system when an internal failure occurs, and less than 10 MVA sounds an alarm. The following protection devices are used according to various types of failures.

Protection devices used in the case of a transformer failure type of internal short-circuit include ratio differential relays, overcurrent relays, Buchholz relays or shock pressure relays, which should only be protected by short-circuit currents and installed separately outside the transformer. There is a disadvantage. Ground fault overcurrent relays or ground fault direction relays are used as protection devices for ground fault primary, primary and secondary short circuits, and ground fault overcurrent relays are used as protection devices for ground fault secondary devices. Is a ground fault protection only. In case of overload and secondary external short circuit, over current relay, secondary low voltage circuit breaker or lead-in fuse is used as a protective device. This is to protect the consumer rather than the transformer.

In addition, if the temperature rises due to the overload, short circuit, or contact with the rated heat, the heat is generated from the coil and iron core inside the transformer, and the temperature of the insulation oil rises in the case of hydraulic type. The temperature sensor is installed at the outside and the switch is manually opened from the outside based on the temperature signal detected by the temperature sensor. However, this has the disadvantage of having to observe the signal from the temperature sensor installed in the transformer one by one, manual operation, and under the proposition of temperature sensing operation, the ambient temperature of 30-40 ° C in summer and -10-20 ° C in winter Since there is a difference in environmental temperature, it is hard to just operate by sensing the temperature, and since it is installed inside the transformer tank, there is no maintenance when repairing.

The present invention has been made to solve the above-mentioned conventional problems, and an object thereof is to provide a bushing installed at a power inflow and outflow site on the primary and secondary sides of a transformer, rather than a conventional bushing for insulation and conduction. Fuse bushings for transformer overload protection with built-in fuses designed to calculate and blow and / or cut off ratings and overloads to provide insulation and conduction as well as to protect transformers and consumers from electrical accidents caused by continuous overload or short circuit current. Is to provide.

1 is a view showing a bushing made of a conventional high-pressure magnetic material or composite material,

2 and 3 is a fuse overload protection fuse bushing according to an embodiment of the present invention, Figure 2 shows a primary high-pressure fuse bushing is installed on the transformer primary side, Figure 3 is a secondary low pressure installed on the transformer secondary side Is a view showing a fuse bushing,

4 is a schematic diagram of a bushing built-in transformer protection fuse installed for the purpose of separating the transformer from the overload or short-circuit current in Figures 2 and 3,

FIG. 5 is a graph illustrating operation time characteristics of a fuse device generally applied for the purpose of protecting the transformer of FIG. 4.

※ Explanation of code for main part of drawing

110,210: bushing housing 111,211: insulated pipe

120,220: Conductor wire 130,230: Fuse element (melting, blocking element)

140,240 bushing upper cap 141,241 fuse replacement nut

150,250: line clamp terminal 161: retaining ring

160, 260: transformer enclosure 270: encapsulant

In order to achieve the above object, the transformer overload protection fuse bushing according to the present invention is installed at the primary and secondary power supply and withdrawal sites of the transformer to insulate the conductive path from the external ground. An insulating housing formed with an insulating tube; A conductor wire installed in the insulated tube to form a lead-in or lead-out conductive path of electric power; And a disconnecting means installed in series with the conductor wire in the insulated tube and blocking the conductive path when an overload continuous current of more than a rated current changeable and an initial starting current flows. (Element) The element is detachably installed in the insulation tube.

Thus, according to the fuse bushing for transformer overload protection according to the present invention, by installing the blocking means for overload protection for the overload capacity of the transformer in the conductor line as a bushing inner conductive path, so that the blocking means to block the conductive path in case of overload. Thus, the transformer is protected from the incoming power source and the output side load from the outside to protect the transformer.

Hereinafter, a fuse bushing for protecting a transformer overload according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Figure 2 is a fuse overload protection fuse bushing according to an embodiment of the present invention, it shows a primary high-pressure fuse bushing installed on the transformer primary side.

In Figure 2, the primary high pressure fuse bushing, the insulating tube 111 is formed in the longitudinal center in the inner center, the outer surface of the housing 110 of the insulating material formed with a plurality of disc projections 112; A conductor wire 120 installed in the insulation tube 111 to form a drawing conductive path of power; When the current flows or short-circuit flows for a predetermined time as a time sufficient to be connected to the conductor wire 120 in the insulated tube 111 in a manner such that the overload of the rating exceeds the transformer function, the conductive path is blocked. However, the built-in fuse 130 as a detachable means detachable in the insulating tube 111; An upper cap 140 coupled to an upper end of the housing 110 using a plurality of fuse replacement nuts 141 to open and close an upper portion of the insulating tube 111; An external power line (not shown) or a separate power line (not shown) for drawing power delivered through the power line to the transformer side passes through the cap 140 to the conductive path in the insulation pipe 111. A line clamp terminal 150 installed on an upper surface of the cap 140 to support communication; And a transformer fixing ring 160 formed at a lower end of the housing 110 to be coupled to the transformer while supporting the lower portion of the conductor wire 120.

Figure 3 is a fuse overload protection fuse bushing according to an embodiment of the present invention, it shows a secondary low-pressure fuse bushing installed on the transformer secondary side.

In FIG. 3, the secondary low pressure fuse bushing includes an insulating tube 211 formed at an inner center thereof in a vertical direction in an inner center thereof, and an outer surface thereof having an approximately cylindrical shape having a cylindrical shape; A conductor wire 220 installed in the insulation tube 211 to form a drawing conductive path for power; When the overcurrent larger than a predetermined current flows for a predetermined time or a short-circuit current flows, the conductive path is cut off in series with the conductor wire 220 installed in the insulator tube 211. A built-in fuse 230 as a blocking means detachably installed in the insulating tube 211; An upper cap 240 coupled to an upper end of the housing 10 using a plurality of fuse replacement nuts 241 to open and close an upper portion of the insulating tube 211; A power supply line (not shown) as a supply path of power output from the secondary side of the transformer and transmitted to the load (not shown) side passes through the upper cap 240 to communicate with the draw conductive path in the insulation pipe 211. A line clamp terminal 250 installed on an upper surface of the cap 240; And an encapsulant 270 encapsulating the conductor wire 220 and the transformer enclosure 260.

4 is a configuration diagram of the bushing built-in transformer protection fuses 130 and 230 as the blocking means in FIGS. 2 and 3, wherein an arc arc tube 301 and a blow element and a blocking element installed in the arc arc tube 301 are shown. 302, upper and lower caps 303 and 304 for blocking the upper and lower portions of the arc arc tube 301, and the conductor wires 120 and 220 and external distribution lines as lead or lead wires of both ends of the blow-off and blocking element 302 and transformers. And connecting terminals 305 and 306 which connect a series with each other (not shown). In particular, the melt and cut-off element 302 has a blow-out portion 302a and a cut-off portion 302b connected in series with each other, and according to the overload ratio (about 120% to 900%) to the transformer rating, from about 0.1 second to 2 hours The melting part 302a is designed to be melted and cut off gradually for a predetermined time according to the magnitude of the overload generated during overload within a predetermined short-circuit current, and the blocking part 302b. ) Is designed to shut off immediately (eg within a few cycles of current) when an overcurrent above the short-circuit current occurs.

Next, the operation of the present invention configured as described above will be described.

Where available, always use the rated voltage available to the power consumption, electrical and electronic products. If the voltage from the outside is not the same as the operating voltage, use a transformer that converts the voltage to the rated voltage for the operation of the equipment or product. Done.

The failure of the transformer is known to be the main cause of the deterioration of the transformer due to external fault voltage, surge, short current, overload. In particular, in the case of a pole-type transformer of outdoor poles installed in a crowded area of the city, an accident occurs when an overload or deterioration proceeds and the transformer breaks down due to an overload in the summer when the power consumption is rapidly increased. In addition to serious damage to life and property, it also leads to loss of electrical equipment and safety hazards.

According to the present invention, a fuse (130,230) designed for the primary and secondary side insulation bushings (inlet and pull insulators) of a transformer is calculated by calculating the rating and overload of the transformer. It is installed to be detachable in series with the conductive path in the association (111, 211), and if the overload occurs in the power drawn into the transformer from the outside or the power drawn from the transformer to the load side, the blown and short-circuit current blocking device of the fuse (130, 230) 302 is separated to cut off the conductive path for power supply. That is, when an excitation current and an overcurrent are generated on the conductive path, the blown-out and short-circuit current blocking device 302 has a constant ratio of overload power designed as shown in FIG. 5. % To 900% kV), each of which is melted and / or interrupted differently from about 0.1 second to about 2 hours, and when the short circuit current of 700% or more of the transformer rating occurs, the breaking portion 302b of the melting and blocking element 302 To cut off within a few cycles of current (approximately 0.2 seconds), and when overcurrent within 700% of the transformer rating occurs, use the melting characteristic of the melting part 302a to adjust the melting time according to the magnitude of the overcurrent generated. By being otherwise cut off, the transformer is protected from overload and short-circuit current, and other operating characteristics of the blow-off and blocking element 302 are generally set as shown in FIG. Rating of the fuse to the use thereof, and also because different types of operating time for the elements of these elements may be set to vary.

Meanwhile, the fuses 130 and 230 in which the melt and cut-off elements 302 are melted and / or cut off, loosen the fuse replacement nuts 141 and 241, and open the bushing upper caps 140 and 240 to insulate the insulator pipes 111 and 211. After opening the top of the, replace with a new fuse.

According to the present invention, it is possible to protect the transformer from overload and to protect various loads on the customer side, thereby reducing the failure, life and economic loss of the transformer by several hundred cases per year. The transformer is as follows.

A pole-type transformer for electric power used for the purpose of supplying electric power by changing the voltage in the power generation / substation or distribution line, which is mainly used for outdoor use, and is a major damage in case of an accident; An isolation transformer, also referred to as a tie transformer, for the purpose of insulating a plurality of systems; An electric furnace transformer having a purpose of supplying electric power to an electric furnace and having various types according to the types of electric furnaces, and mainly having a large current on a secondary side, having a large load variation and a large% reactance of a circuit; A power transformer such as a rectifier SCR, which has various types according to the rectifier number, and is integrated with the rectifier, and includes a transformer for a semiconductor power converter having a high loss and a high temperature rise due to a large harmonic component; A special transformer used for distribution in a ship, manufactured according to the NK standard, etc., which requires strict verification; As a transformer used in an explosive flammable environment, since the use environment is important, it can be installed and applied to the primary side and the secondary side of an explosion-proof structure transformer, which is expected to have a very large effect especially when the fuse bushing according to the present invention is expected. The fuse bushing may be applicable to various transformers without departing from the technical spirit of the present invention.

As described in detail above, according to the fuse overload protection fuse bushing according to the present invention, it is possible to protect the transformer from an output load or an input current higher than the rated value, and to protect the device from abnormal high voltage induced in the transformer. It is easy to maintain and replace the fuse inside the magnetic and composite bushings and can prevent damage or explosion due to deterioration of the transformer or accumulated deterioration, thus protecting people or property and entering the transformer primary. It is possible to protect the power equipment and the consumer from the overcurrent induced in the secondary by the fault current, and also to install the transformer only by using the bushing which is necessary for the existing without installing a separate temperature rise prevention switch (CSP) or a protective relay on the outside of the transformer. There is an effect to protect.

Claims (5)

In the bushing installed in the power input or draw-out of the transformer to insulate the conductive path from the external ground, An insulating housing having an insulating tube formed in an inner center thereof; A conductor wire installed in the insulated tube to form a lead-in or lead-out conductive path of electric power; And It is connected to the conductor wire in the insulated pipe in series and blocks the conductive path when a predetermined current flows, but melts and cuts in different time range according to the overload ratio of the transformer when an overcurrent below a short circuit current occurs. A fuse bushing for transformer overload protection, characterized in that it comprises a (iv) section and a blocking means for shutting off within a few cycles of current when an overcurrent of the short circuit current or more occurs. delete delete delete The method of claim 1, The melted part is melted within 600 seconds, 60 seconds, and several seconds for 180%, 300%, and 700% of the transformer rated current, and the cutoff portion of the current for a current equal to the short circuit current of 700% or more of the rated current. Fuse bushing for transformer overload protection, characterized by separation from energization within a few cycles.