An electric furnace transformer

Abstract

The invention discloses an electric furnace transformer, comprising a voltage regulating switch, a voltage regulating coil, a high-voltage coil, a low-voltage coil and a series coil. The voltage regulating coil, the high-voltage coil, the low-voltage coil and the series coil are wound on the same iron core. The series coil can increase the voltage on the coil based on the principle of electromagnetic induction, thereby reducing the current of the coil. There is no need to set up a transformer separately. The current transmitted to the voltage regulating coil can be reduced while the transmission power remains unchanged, thereby ensuring that a low-cost voltage regulating switch can be selected, so as to reduce the possibility that the voltage regulating switch cannot work normally because the current of the voltage regulating coil is too high, so that the voltage regulating switch can normally change the turns ratio between the voltage regulating coil and the low-voltage coil, that is, the low-voltage coil outputs a voltage and current that meets the power demand of the electric furnace or arc furnace.

Description

Technical Field

[0001] The invention relates to the technical field of electrical engineering, and in particular to an electric furnace transformer. Background Art

[0002] In order to make the electric furnace or electric arc furnace work normally, an electric furnace transformer is usually used to power the electric furnace or electric arc furnace. The electric furnace transformer is provided with a high-voltage coil 11, a voltage regulating circuit 12 and a low-voltage coil 13, such as Figure 1 As shown, Figure 1 This is a structural schematic diagram of an electric furnace transformer in the prior art. The input end of the high-voltage coil 1, namely phase A, phase B and phase C, is connected to the power grid. The sliding end of the voltage regulating switch in the voltage regulating circuit 12 is connected to the voltage regulating coil. The voltage regulating coil is connected in series with the high-voltage coil 11 and is inductively connected to the low-voltage coil 13. The output end of the low-voltage coil 13 is connected to the power input end of the electric furnace or arc furnace. By adjusting the voltage regulating switch in the voltage regulating circuit, the turns ratio of the voltage regulating coil and the low-voltage coil 13 can be changed, so that the low-voltage coil 13 outputs corresponding voltage and current.

[0003] As the electric furnace and arc furnace industry develops in the direction of large-scale and centralized benefits, in order to respond to the country's call for energy conservation, electric furnaces or arc furnaces require electric furnace transformers to be able to output large capacity, low voltage and high current. The voltage regulating switch of the voltage regulating circuit 12 in the current electric furnace transformer is usually set as a three-phase integrated voltage regulating switch, such as Figure 1 As shown, the maximum current that the three-phase integrated voltage regulating switch can operate normally is 600A. When the current flowing through the voltage regulating circuit 12 is greater than 600A, a single-phase voltage regulating switch needs to be provided in each phase of the voltage regulating circuit 12. The price of the single-phase voltage regulating switch is relatively high, which increases the cost of the electric furnace transformer.

[0004] In addition, in order to enable the electric furnace transformer to output large capacity, low voltage and large current, the prior art also sets another series transformer in the electric furnace transformer. The series transformer senses the voltage on the high-voltage coil 11 and increases its own voltage, and is connected in series with the voltage regulating coil. After increasing its own voltage, it outputs a reduced current to the voltage regulating coil. Therefore, the normal operation of the three-phase integrated voltage regulating switch can be guaranteed. However, setting another series transformer also increases the cost of the electric furnace transformer and is more difficult to manufacture. Summary of the invention

[0005] The object of the present invention is to provide an electric furnace transformer, which does not require an additional transformer to be set up. The current transmitted to the voltage regulating coil can be reduced while its transmission power remains unchanged, thereby ensuring that a low-cost voltage regulating switch can be selected to reduce the possibility that the voltage regulating switch cannot work normally due to excessive current in the voltage regulating coil, so that the voltage regulating switch can normally change the turns ratio between the voltage regulating coil and the low-voltage coil, that is, the low-voltage coil outputs a voltage and current that meets the power demand of the electric furnace or arc furnace.

[0006] In order to solve the above technical problems, the present invention provides an electric furnace transformer, comprising a voltage regulating switch, a voltage regulating coil, a high-voltage coil and a low-voltage coil, and also comprising a series coil, wherein the voltage regulating coil, the high-voltage coil, the low-voltage coil and the series coil are wound on the same iron core, a first end of the series coil is connected to one end of the voltage regulating coil, and a second end is grounded, the voltage regulating coil is also connected to a sliding end of the voltage regulating switch, and a fixed end of the voltage regulating switch is grounded;

[0007] The series coil is used for induction with the high-voltage coil to boost its own voltage and transmit the current corresponding to the boosted voltage to the voltage regulating coil.

[0008] Preferably, the voltage regulating switch is a three-phase integrated voltage regulating switch.

[0009] Preferably, it also includes:

[0010] A tap switch whose fixed end is connected to the first end of the series coil and whose movable end is connected to the first end or the second end of the voltage regulating coil is used to change the connection mode between the series coil and the voltage regulating coil.

[0011] Preferably, phase a, phase b and phase c of the low-voltage coil output end are connected to the first power input end of the electric furnace or the electric arc furnace, and phase x, phase y and phase z are connected to the second power input end of the electric furnace or the electric arc furnace.

[0012] Preferably, it also includes:

[0013] A control module whose output end is connected to the control end of the voltage regulating switch is used to adjust the sliding end of the voltage regulating switch based on user instructions to change the connection position between the sliding end of the voltage regulating switch and the voltage regulating coil, so as to change the turns ratio between the voltage regulating coil and the low-voltage coil.

[0014] Preferably, it also includes:

[0015] An oil tank filled with transformer oil, used for cooling the voltage regulating coil, the series coil, the high-voltage coil, the low-voltage coil, the iron core and the voltage regulating switch;

[0016] The voltage regulating coil, the series coil, the high-voltage coil, the low-voltage coil, the iron core and the voltage regulating switch are all immersed in the transformer oil in the oil tank.

[0017] Preferably, the oil tank is provided with a connection terminal connected to the output end of the low-voltage coil, arranged outside the oil tank and all arranged on the same surface of the oil tank, for connecting to the power input end of the electric furnace or the electric arc furnace;

[0018] A side of the oil tank where the connecting terminals are located is a magnetic isolation plate to isolate the heat of the connecting terminals from outside the oil tank.

[0019] Preferably, the magnetic isolation plate is an aviation aluminum plate or a non-magnetic plate.

[0020] Preferably, the conductors of the voltage regulating coil, the series coil, the high-voltage coil and the low-voltage coil all have a yield strength not less than a preset value, so that the clamping force of each coil is not less than the preset clamping force.

[0021] The present application provides an electric furnace transformer, comprising a voltage regulating switch, a voltage regulating coil, a high-voltage coil, a low-voltage coil and a series coil. The voltage regulating coil, the high-voltage coil, the low-voltage coil and the series coil are wound on the same iron core. The series coil can increase the voltage on its coil based on the principle of electromagnetic induction, thereby reducing the current of its coil. There is no need to set up a separate transformer. The current transmitted to the voltage regulating coil can be reduced while its transmission power remains unchanged, thereby ensuring that a low-cost voltage regulating switch can be selected to reduce the possibility that the voltage regulating switch cannot work normally due to excessive current of the voltage regulating coil, so that the voltage regulating switch can normally change the turns ratio between the voltage regulating coil and the low-voltage coil, that is, the low-voltage coil outputs a voltage and current that meets the power demand of the electric furnace or arc furnace. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the prior art and the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0023] Figure 1 It is a structural schematic diagram of an electric furnace transformer in the prior art;

[0024] Figure 2 A schematic diagram of the structure of an electric furnace transformer provided by the present invention;

[0025] Figure 3 A schematic diagram of the specific structure of an electric furnace transformer provided by the present invention;

[0026] Figure 4 A schematic diagram of the specific structure of another electric furnace transformer provided by the present invention;

[0027] Figure 5 A schematic diagram of an oil tank of an electric furnace transformer provided by the present invention. DETAILED DESCRIPTION

[0028] The core of the present invention is to provide an electric furnace transformer, which does not require an additional transformer to be set up. The current transmitted to the voltage regulating coil can be reduced while its transmission power remains unchanged, thereby ensuring that a low-cost voltage regulating switch can be selected to reduce the possibility that the voltage regulating switch cannot work normally due to excessive current in the voltage regulating coil, so that the voltage regulating switch can normally change the turns ratio between the voltage regulating coil and the low-voltage coil, that is, the low-voltage coil outputs a voltage and current that meets the power demand of the electric furnace or arc furnace.

[0029] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] Please refer to Figure 2 , Figure 2 The present invention provides a schematic diagram of the structure of an electric furnace transformer, the electric furnace transformer comprising:

[0031] The voltage regulating switch 5, the voltage regulating coil 3, the high voltage coil 1 and the low voltage coil 4 also include a series coil 2. The voltage regulating coil 3, the high voltage coil 1, the low voltage coil 4 and the series coil 2 are wound on the same iron core. The first end of the series coil 2 is connected to one end of the voltage regulating coil 3, and the second end is grounded. The voltage regulating coil 3 is also connected to the sliding end of the voltage regulating switch 5, and the fixed end of the voltage regulating switch 5 is grounded.

[0032] The series coil 2 is used for induction with the high-voltage coil 1 to boost its own voltage and transmit the current corresponding to the boosted voltage to the voltage regulating coil 3 .

[0033] The applicant took into account that the electric furnace transformer in the prior art is usually composed of a high-voltage coil 1, a low-voltage coil 4, a voltage regulating coil 3 and a voltage regulating switch 5. The voltage regulating switch 5 is generally set as a three-phase integrated voltage regulating switch, but the three-phase integrated voltage regulating switch can withstand a relatively small current, generally a maximum of 600A, while today's electric furnaces or arc furnaces require large-capacity electric furnace transformers that can output low voltage and high current. In order to meet the electricity demand of electric furnaces or arc furnaces, the prior art generally replaces the three-phase integrated voltage regulating switch with a single-phase voltage regulating switch that can withstand a larger current, but the single-phase voltage regulating switch is more expensive. For example, in the prior art, the on-load voltage-regulating transformer circuit with a variable flux neutral point directly connected in series with the voltage-regulating coil, the on-load voltage-regulating transformer circuit with a variable flux neutral point directly connected in series with the coarse and fine voltage-regulating coils, and the on-load voltage-regulating transformer circuit with a variable flux neutral point directly connected in series with the voltage-regulating coil in positive and negative directions, due to the limitation of the three-phase integrated voltage-regulating switch, can only be used in small and medium-sized electric furnaces and arc furnaces, that is, electric furnaces and arc furnaces with smaller capacity and smaller current. If it is to be used in large-capacity, low-voltage and high-current electric furnaces or arc furnaces, the three-phase integrated voltage-regulating switch needs to be replaced with three single-phase voltage-regulating switches, but this will increase the cost.

[0034] Another solution in the prior art is to set up a series transformer in the electric furnace transformer. The series transformer senses the voltage on the high-voltage coil 1 and increases its own voltage, and is connected in series with the voltage regulating coil 3. After increasing its own voltage, it outputs a reduced current to the voltage regulating coil 3. The current is a smaller current that the three-phase integrated voltage regulating switch can withstand. Although this method can reduce the increased cost when switching to a single-phase voltage regulating switch, adding an additional series transformer also increases the cost and increases the size of the entire electric furnace transformer. Moreover, the connection relationship between the series transformer and the high-voltage coil 1 is relatively complicated. The series transformer and the electric furnace transformer need to be connected in series according to the double-pancake 8-shaped coil, which increases the manufacturing difficulty and has high requirements on the manufacturing process, that is, special process equipment is required, and it needs to be designed and manufactured by professional manufacturers. If there is a problem in the operation control, it will affect the safe operation of the equipment. For example, the on-load tap-changing transformer line with auxiliary transformer and the on-load tap-changing transformer line with auto-coupling transformer in the prior art can be used for large capacity and low voltage and large current, but they are respectively equipped with auxiliary transformer and auto-coupling transformer, that is, they are composed of two transformers (main transformer plus auxiliary transformer and main transformer plus auto-coupling transformer), and their cost is also increased a lot.

[0035] In order to solve the above technical problems, the present application provides a series coil 2 connected in series with the voltage regulating coil 3, and the voltage regulating coil 3, the high voltage coil 1, the low voltage coil 4 and the series coil 2 are wound on the same iron core, without adding an iron core, thus reducing the space of the electric furnace transformer. Please refer to Figure 3 , Figure 3The present invention provides a specific structural diagram of an electric furnace transformer, wherein each coil is three-phase, and the A phase, B phase and C phase of the high-voltage coil 1 are connected to the power grid respectively, and the series coil 2 is induced by the high-voltage coil 1, so that its own voltage is boosted while its transmission power remains unchanged. Accordingly, the current output by the series coil 2 is small, and the series coil 2 is connected in series with the voltage regulating coil 3, and the small current obtained after the boost is transmitted to the voltage regulating coil 3, so as to ensure that when the three-phase integrated voltage regulating switch is selected, the three-phase integrated voltage regulating switch can work normally, and the voltage regulating coil 3 is connected to the sliding end of the voltage regulating switch 5. In order to ensure the safe operation of the electric furnace transformer, the fixed end of the voltage regulating coil 3 needs to be grounded, such as Figure 3 By changing the connection position between the sliding end of the voltage regulating switch 5 and the voltage regulating coil 3, the turns ratio between the voltage regulating coil 3 and the low-voltage coil 4 can be changed, so that the low-voltage coil 4 can step up or down the voltage on the voltage regulating coil 3 to the voltage required by the electric furnace or arc furnace, and the a phase, b phase and c phase of the low-voltage coil 4 are connected to the power input end of the electric furnace or arc furnace, so that the voltage and current obtained by stepping up or down the voltage regulating coil 3 are output to the electric furnace or arc furnace, so that the electric furnace or arc furnace can work normally.

[0036] Among them, the winding order of each coil on the iron core can be but is not limited to the voltage regulating coil 3, the series coil 2, the high-voltage coil 1 and the low-voltage coil 4. The voltage regulating switch 5 is arranged at the outermost end, and each gear of the voltage regulating coil 3 is led out with a tap, so that the sliding end of the voltage regulating switch 5 can be connected to the corresponding gear of the voltage regulating coil 3 to change the turns ratio between the voltage regulating coil 3 and the low-voltage coil 4, so that the low-voltage coil 4 outputs the corresponding voltage and current.

[0037] In addition, since the series coil 2 can induce the high-voltage coil 1 to increase its own voltage, and then the voltage on the low-voltage coil 4 is increased or decreased by the voltage regulating coil 3, the capacity of the electric furnace transformer can be increased, that is, the output power of the electric furnace transformer is higher, for example, the capacity can reach more than 100MVA.

[0038] In addition, the voltage regulating coil 3 adopts a layered distribution, the high-voltage coil 1 and the series coil 2 adopt a continuous distribution to improve the capacitance distribution, and the low-voltage coil 4 adopts a double-pancake distribution. Therefore, the multi-channel parallel confluence can meet the requirements of large currents of 80-90kA.

[0039] In summary, the series coil 2 in the present application can increase the voltage on the coil based on the principle of electromagnetic induction, thereby reducing the current of the coil. There is no need to set up a transformer separately. The current transmitted to the voltage regulating coil 3 can be reduced while keeping its transmission power unchanged, thereby ensuring that a low-cost voltage regulating switch 5 can be selected to reduce the possibility that the voltage regulating switch 5 cannot work normally due to the excessive current of the voltage regulating coil 3, so that the voltage regulating switch 5 can normally change the turns ratio between the voltage regulating coil 3 and the low-voltage coil 4, that is, the low-voltage coil 4 outputs a voltage and current that meets the power demand of the electric furnace or arc furnace.

[0040] Based on the above embodiments:

[0041] As a preferred embodiment, the voltage regulating switch 5 is a three-phase integrated voltage regulating switch.

[0042] In order to save a certain amount of cost, the voltage regulating switch 5 in the present application is set as a three-phase integrated voltage regulating switch, which can not only adjust the turns ratio between the voltage regulating coil 3 and the low-voltage coil 4, but also reduce the cost.

[0043] In addition, the voltage regulating switch 5 in the present application can also be set as a single-phase voltage regulating switch, so as to further increase the capacity of the electric furnace transformer, which is not limited in the present application.

[0044] As a preferred embodiment, it also includes:

[0045] The tap switch, whose fixed end is connected to the first end of the series coil 2 and whose movable end is connected to the first end or the second end of the voltage regulating coil 3, is used to change the connection mode between the series coil 2 and the voltage regulating coil 3.

[0046] The applicant has taken into account that different electric furnaces or arc furnaces in the prior art require different voltages. In order to meet the electricity demand of the electric furnace or arc furnace, the electric furnace transformer needs to frequently switch the output voltage. In order to solve the above technical problems, a tap switch is connected between the series coil 2 and the voltage regulating coil 3 in the present application, so that the connection relationship between the series coil 2 and the voltage regulating coil 3 can be changed, thereby realizing voltage conversion.

[0047] In addition, by switching the connection mode between the series coil 2 and the voltage regulating coil 3, the voltage on the voltage regulating coil 3 can be changed, and the voltage regulating range of the arc transformer can be increased to further meet the electricity demand of the electric furnace or arc furnace.

[0048] For example, see Figure 3 , Figure 3 The voltage regulating coil 3 is a 13-speed coil. By switching the connection method between the series coil 2 and the voltage regulating coil 3, the voltage regulating range of the voltage regulating coil 3 can be increased to 13*2+1 speed, that is, 27 speeds, further expanding the voltage regulating range of the electric furnace transformer.

[0049] As a preferred embodiment, phase a, phase b and phase c of the output end of the low-voltage coil 4 are connected to the first power input end of the electric furnace or arc furnace, and phase x, phase y and phase z are connected to the second power input end of the electric furnace or arc furnace.

[0050] Please refer to Figure 4 , Figure 4 Another specific structural diagram of an electric furnace transformer provided by the present invention. The applicant has considered that different electric furnaces or electric arc furnaces have different wiring methods. Some electric furnaces or electric arc furnaces only need to connect the a phase, b phase and c phase of the low-voltage coil 4, while some electric furnaces or electric arc furnaces need to connect the electric furnace transformer with the low-voltage side lead wire externally sealed. The low-voltage coil 4 in the electric furnace transformer with the low-voltage side lead wire externally sealed not only has the a phase, b phase and c phase connected to the electric furnace or electric arc furnace, but also its x phase, y phase and z phase need to be connected to the electric furnace or electric arc furnace to ensure the normal operation of the electric furnace or electric arc furnace.

[0051] It should be noted that in the present application, phases a, b and c of the low-voltage coil 4 are connected to the inner delta of the electric furnace transformer, and phases x, y and z of the low-voltage coil 4 are connected to the outer delta of the electric furnace transformer.

[0052] As a preferred embodiment, it also includes:

[0053] The control module whose output end is connected to the control end of the voltage regulating switch 5 is used to adjust the sliding end of the voltage regulating switch 5 based on the user's instructions to change the position where the sliding end of the voltage regulating switch 5 is connected to the voltage regulating coil 3, so as to change the turns ratio between the voltage regulating coil 3 and the low-voltage coil 4.

[0054] In order to facilitate the user to change the connection position of the sliding end of the voltage regulating switch 5 and the voltage regulating coil 3, a control module is also provided in the present application. The user can change the connection position of the sliding end of the voltage regulating switch 5 and the voltage regulating coil 3 through the control module, thereby changing the turns ratio between the voltage regulating coil 3 and the low-voltage coil 4, so that the low-voltage coil 4 outputs the corresponding voltage and current.

[0055] In addition, the control module in the present application can be but is not limited to a single gear control module. For example, the user can operate the control module based on his own needs and the current position of the sliding end of the voltage regulating switch 5 connected to the voltage regulating coil 3. Each time the control module is operated once, the sliding end of the voltage regulating switch 5 is switched from the position connected to the voltage regulating coil 3 to the previous gear or the next gear connected to the voltage regulating coil 3. The user can also directly operate the control module so that the voltage regulating switch 5 is switched to the gear of the voltage regulating coil 3 that the user wants at one time. This application does not limit this.

[0056] As a preferred embodiment, it also includes:

[0057] The oil tank filled with transformer oil is used to cool down the voltage regulating coil 3, the series coil 2, the high voltage coil 1, the low voltage coil 4, the iron core and the voltage regulating switch 5;

[0058] The voltage regulating coil 3, the series coil 2, the high voltage coil 1, the low voltage coil 4, the iron core and the voltage regulating switch 5 are all immersed in the transformer oil in the oil tank.

[0059] The applicant has taken into account that the temperature of the voltage regulating coil 3, the series coil 2, the high-voltage coil 1, the low-voltage coil 4, the iron core and the voltage regulating switch 5 will increase during operation, thereby affecting the normal operation of each coil. In order to solve the above problem, the electric furnace transformer in the present application is provided with an oil tank, which is filled with transformer oil. The voltage regulating coil 3, the series coil 2, the high-voltage coil 1, the low-voltage coil 4, the iron core and the voltage regulating switch 5 are immersed in the transformer oil, and each coil, the iron core and the voltage regulating switch 5 can be cooled, thereby ensuring that the electric furnace transformer can work normally and improving the life of each coil, the iron core and the voltage regulating switch 5.

[0060] As a preferred embodiment, the oil tank is provided with a connection terminal connected to the output end of the low-voltage coil 4, which is arranged outside the oil tank and all arranged on the same surface of the oil tank, and is used to connect to the power input end of the electric furnace or arc furnace;

[0061] The side of the oil tank where the wiring terminals are located is a magnetic isolation plate to isolate the heat of the wiring terminals from outside the oil tank.

[0062] Please refer to Figure 5 , Figure 5 A schematic diagram of an oil tank of an electric furnace transformer provided by the present invention, A, B and C in the figure are ports for connecting the high-voltage coil 1 to the power grid, and a, b and c are connection ports for connecting the low-voltage coil 4 to the electric furnace or arc furnace.

[0063] The applicant considers that when the electric furnace transformer supplies power to the electric furnace or electric arc furnace, the electric furnace transformer will output low voltage and high current. In order to ensure the normal connection between the low-voltage coil 4 and the electric furnace or electric arc furnace, a terminal is provided on the outside of the oil tank to facilitate the connection between the low-voltage coil 4 and the electric furnace or electric arc furnace. However, when the electric furnace transformer outputs low voltage and high current, the electric furnace transformer will generate leakage magnetic flux, and the temperature at the connection between the low-voltage coil 4 and the electric furnace or electric arc furnace is high, which causes the oil tank and its structural parts to heat up easily, affecting the safe operation of the electric furnace transformer. For this reason, the applicant sets one side of the terminal provided on the oil tank as a magnetic isolation plate, thereby shielding the heat outside the oil tank and ensuring the normal operation of each coil. The impact of local overheating is reduced.

[0064] As a preferred embodiment, the magnetic isolation plate is an aviation aluminum plate or a non-magnetic plate.

[0065] The magnetic isolation plate in the present application is set to be an aviation aluminum plate or a non-magnetic plate (20Mn23Al), and both the aviation aluminum plate and the non-magnetic plate can achieve temperature isolation.

[0066] In addition, aviation aluminum plates are also characterized by high hardness, and non-magnetic plates are also easy to process.

[0067] Of course, the present application does not limit the material to be used as the magnetic isolation plate, as long as it can achieve temperature isolation.

[0068] As a preferred embodiment, the conductors of the voltage regulating coil 3, the series coil 2, the high-voltage coil 1 and the low-voltage coil 4 all have a yield strength not less than a preset value, so that the clamping force of each coil is not less than the preset clamping force.

[0069] When the electric furnace transformer outputs low voltage and high current, arc heating (commonly known as sparking) is generated at the electrical connection between the low-voltage coil 4 and the electric furnace or arc furnace. The load is an impact load. In order to enhance the short-circuit resistance of the electric furnace transformer and reduce the impact of the impact load on the normal operation of the electric furnace transformer, the yield strength of the wire of each coil in the present application is not less than a preset value, for example, 220N / mm^2, so that the clamping force of each coil is not less than the preset clamping force, that is, the distance between the turns in the coil is reduced.

[0070] In addition, cardboard tubes, extra-hard T4 pads or internal and external support bars can be added at both ends of each coil in the electric furnace transformer to further ensure that the clamping force of each coil is not less than the preset clamping force. For example, the clamping force of the coil is controlled at 7MPa to increase the coil's ability to resist short circuits.

[0071] It should also be noted that, in this specification, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0072] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An electric furnace transformer, comprising a voltage regulating switch, a voltage regulating coil, a high-voltage coil and a low-voltage coil, characterized in that: It also includes a series coil, wherein the voltage regulating coil, the high voltage coil, the low voltage coil and the series coil are wound on the same iron core, the first end of the series coil is connected to one end of the voltage regulating coil, and the second end is grounded, the voltage regulating coil is also connected to the sliding end of the voltage regulating switch, and the fixed end of the voltage regulating switch is grounded; The series coil is used to sense the high-voltage coil to boost its own voltage and transmit the current corresponding to the boosted voltage to the voltage regulating coil; The voltage regulating coil adopts layer distribution, the high voltage coil and the series coil adopt continuous distribution to improve capacitance distribution, and the low voltage coil adopts double pancake distribution; Correspondingly, the a phase, b phase and c phase of the low voltage coil output end are connected to the first power input end of the electric furnace, and the x phase, y phase and z phase are connected to the second power input end of the electric furnace; Correspondingly, it also includes: An oil tank filled with transformer oil, used for cooling the voltage regulating coil, the series coil, the high-voltage coil, the low-voltage coil, the iron core and the voltage regulating switch; The voltage regulating coil, the series coil, the high-voltage coil, the low-voltage coil, the iron core and the voltage regulating switch are all immersed in the transformer oil in the oil tank; Correspondingly, the oil tank is provided with a connection terminal connected to the output end of the low-voltage coil, which is arranged outside the oil tank and all arranged on the same surface of the oil tank, and is used to connect to the power input end of the electric furnace; A side of the oil tank where the connecting terminal is located is a magnetic isolation plate to isolate the heat of the connecting terminal from outside the oil tank; Correspondingly, the conductors of the voltage regulating coil, the series coil, the high-voltage coil and the low-voltage coil are all conductors with a yield strength not less than a preset value, so that the pressing force of each coil is not less than the preset pressing force; Correspondingly, it also includes: Add cardboard tubes, extra-hard T4 pads or internal and external support bars at both ends of each coil of the electric furnace transformer.

2. The electric furnace transformer according to claim 1, characterized in that: The voltage regulating switch is a three-phase integrated voltage regulating switch.

3. The electric furnace transformer according to claim 1, characterized in that: Also includes: A tap switch whose fixed end is connected to the first end of the series coil and whose movable end is connected to the first end or the second end of the voltage regulating coil is used to change the connection mode between the series coil and the voltage regulating coil.

4. The electric furnace transformer according to claim 1, characterized in that: Also includes: A control module whose output end is connected to the control end of the voltage regulating switch is used to adjust the sliding end of the voltage regulating switch based on user instructions to change the connection position between the sliding end of the voltage regulating switch and the voltage regulating coil, so as to change the turns ratio between the voltage regulating coil and the low-voltage coil.

5. The electric furnace transformer according to claim 1, characterized in that: The magnetic isolation plate is an aviation aluminum plate or a non-magnetic plate.

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