Reactive ballast arrangement
SUBSTANCE: invention is referred to electric engineering and can be used for supplemental reactivity of an arc furnace transformer. Reactive ballast arrangement (V) for the arc furnace consists of a choke coil (1) with an open switch (2) for load increment changing which is suitable for installation of the choke coil (1) reactance under load. Reactive ballast arrangement (V) is connected before the transformer of the arc furnace (O) used, in particular, for steel making.
EFFECT: simplifying and improving accuracy of reactivity installation.
12 cl, 3 dwg
The invention relates to reactive ballast device for an electric arc furnace, in particular for the installation of additional reactance transformer of an electric arc furnace.
Before electric arc furnace, as it is used, for example, for melting steel, usually included transformer, which sets the desired electric arc alternating voltage. As with the electric arc furnace are removed very high power and pre-enabled transformer must be transmitted to the high alternating voltages, such transformers are typically placed in an insulating means to avoid spark overlap.
Parameter which is important for AC voltage and AC is the reactivity, that is, the reactance of the conductor, for example a streamlined shock coil.
For various operating States of an electric arc furnace it is desirable to have the ability to set different reactivity. With this purpose, it is known that in the previously enabled transformer embedded device to install reactivity with a choke coil and switch speed load. In a typical case, such devices with coils and active part of the transformer placed in a vessel filled with an insulating medium.
To install an electric arc furnace without the integrated transformer tank additional reactivity, in addition, it is known that out of the transformer, for example in the outdoor switchgear, are mounted choke coils without ferromagnetic core as an additional reactivity.
But with so more reactively it is impossible to establish optimal for all operating States of an electric arc furnace reactivity under load.
Therefore, in practice, many of the installation of electric arc furnaces operate with a permanently pre-selected reactivity. Used for this choke coil has at least one outlet, which forks flowing through the coil current after a certain number of turns and thereby gives definitely set the reactance of the transformer. To give the desired reactivity of the exhaust is mounted permanently. However, it should be taken change, if after a long period of work revealed that the reactivity mode under load, i.e. when the furnace is installed not in the best way that, for example, leads to an undesirable increase in energy consumption, or that the reactivity should be adjusted depending on the process. For this disadvantageous way you want to turn off the power supply, thereby stopping the furnace and repair the transformer with another tap on the choke coil.
The first object of the invention is to create a device with which you can just install, in particular, the reactivity included before the transformer.
The second objective of the invention is to create a transformer through which reactivity can be set as accurately as possible.
The third objective of the invention is to create an electric arc furnace, in particular for melting steel, which mode under load possible optimally and economically supplied with energy.
The first task in accordance with the invention is solved by the fact that the proposed reactive ballast device, in particular for an electric arc furnace with a choke coil and open the switch speed of the load, and the switch speed of the load is made with possibility of installation of reactivity choke coils under load.
Corresponding to the invention the combination of choke coils with an open switch speed load provides the possibility of installing a pre-reactivity under load, so that in accordance with production needs can always be selected optimal preliminary or additional reactivity, especially as applied to the load mode of an electric arc furnace.
Jet ball is astoe device is not limited in its application to install reactivity for an electric arc furnace or electric arc furnace transformer. It can also be switched to other energy consumers or equipment, the parameters of which are determined, in particular by reactivity.
The preferred way for reactive ballast device selected is free, with dry insulation choke coil without a ferromagnetic core. In the case of choke coils without ferromagnetic core with dry insulation is not used insulating oil, so maintenance costs are reduced and reduced fire risk, resulting in increased efficiency and harmlessness to the environment.
In addition, the choke coil has a suitable number of seats allotment, which corresponds to a certain number of turns of the coil. Since the inductance and, thus, the impedance of the coil depends on the number of coils through which current flows in the coil, can be achieved through the branches of the AC current flowing in the coil, drain manual way to set the impedance of the coil and, thus, reactivity, i.e. reactive resistance with alternating current, in accordance with the stages of the places of diversion.
In a preferred further development of reactive ballast device combined with a choke coil free switch speed load has a number of input contacts at least one output contact, and a switching element.
When this switching element is configured to toggle between a variable connection, at least one of the input contact to the output contact. If several input pins of the switching element can thus be connected, respectively, one or more input contact to the output contact. By an appropriate installation switching element output, thus, operated on the same or any output pin. Switch speed load contains, in addition, a tank with an insulating medium, which is made with the possibility of placing him in the switching element. Due to the insulating means is eliminated spark breakdown due to high voltage. Due to the insulating properties of the insulating means is reduced spark gap, so that the constructive dimensions generally decrease.
The switching element includes a suitable way for some number of inputs and at least one output, and one or each output of correlated node bifurcation, which incorporate at least two branches of the bridge circuit, and the branches, respectively, are deactivatable in the inclusion, and the branches, respectively, are varied way connected with the inputs and is therefore, its, pairwise interconnected through a cross-connection is connected to the connection point of the load, in particular, the vacuum switch.
It is related to the output switching element node branching converge related to a bridge circuit branches, and bridge circuit contains at least two branches. Branch contact inputs switching element and may separately communicate with different inputs, which are applied to the inputs multiple branches or only, respectively, one branch on the respective one input. In particular, can be implemented by varying the contact due to displacement of branches between different inputs. If all branches are applied to one input of or all of the branches are in contact with this entry, you specify one position of the stage. If, on the contrary, the two branches attached to two different inputs, it is determined by the position of the bridge. With only two branches, there is only one position of the stage and one position of the bridge. Similarly performed switching element provides the capability of switching under load, and switching from one position level to another is carried out consistently through the formation position of the bridge.
The branches of the bridge circuit of the switching element are connected in pairs with cross-connections, which are deactivatable through, the respectively, the connection point of the load. Between nodes branching and cross-connections branch, for its part, provided, respectively, switch places. If you now place the switch on separate branches deactivated, for example, that these branches move with each one input on each of the other input, that are associated with those branches of the cross-connection take, first of all, load and can also align the fluctuations of current and voltage in the region of the branching node and to eliminate the existing congestion at the switch. Now the transverse connection locations for load switching can be disabled and disconnected from the current flow branches can move. Place the load is preferably determined by vacuum circuit breakers, vacuum circuit breakers as circuit breakers due to the screening action of the vacuum operated reliably and resistant to wear. Besides the branches between transverse joints and places of contact on the input side appropriately equipped with throttle elements that bridge configuration ensures essentially uniform distribution of the load in the circuit.
The desired execution reactive ballast device is largely due to the fact that the number of taps of the throttle is tuski coincides with the number of input contacts of the switch of load and speed, accordingly, the junction is connected to the input pin. While preferred is a linear mapping of the locations of the taps to the input pins, so that the reference input of contacts from the specified sequence corresponds to increasing or decreasing reactivity choke coils. Thus is desirable to-one correspondence between the levels of reactivity and the input contacts.
In addition, there is a viable way-to-one correspondence between input and output contacts of the switch speed of the load and the inputs and outputs of the switching element. Thus, in particular, the inputs of the switching element exactly match the speed of reactivity. Through the switching element as part of the switch speed of the load, thus, expressed approval of the reactance of the transformer by selecting a stage with seats branches of the choke coils.
The second task in accordance with the invention is solved by a transformer, in particular for an electric arc furnace, which correlated reactive ballast device of the above type.
In the transformer is the preferred way built an additional device for the installation of reactivity with a choke coil and switch the speed of the load.
Tert what I task in accordance with the invention is solved in an electric arc furnace, in particular, for smelting steel, to which is connected a transformer of the above type.
In the following description is explained in more detail an example implementation of the invention with reference to the drawings, in which, in schematic image shows the following:
Figure 1 - reactive ballast device with a choke coil without ferromagnetic core and switch speed load
Figure 2 - the process of switching the switching element between the position of the speed and position of the bridge in 6 separate views And F, and
Figure 3 - linear circuit electric arc furnace with transformer and reactive ballast device of the aforementioned type.
Figure 1 generally shows a reactive ballast device V with a choke coil 1 without ferromagnetic core with a free switch 2-speed load. Choke coil 1 without ferromagnetic core through the point 3 power supply connected to the current network and equipped with a number of evenly placed seats 4-way, through which flows through the choke coil 1 without ferromagnetic core current can branch out after, respectively, significance isometric partial section of the flow through the coil. In necessary case, the choke coil 1 without ferromagnetic core may be placed is to be cleansed and purified in the tank 5, which is shown here by the dotted line.
Free switch 2-speed load has a steel hull 6, the inner space 7 which is filled with an insulating medium, in particular oil. Switch 2-speed load is supplied with a certain number of input pins 8, which are connected by a wire with Seating for 4 taps choke coil 1 without a ferromagnetic core. In the inner space 7 steel 6 input pins 8 are inputs for localized there switching element 9, which is shifted variable as a whole. The output switching element 9 via the output contact 10 leads to the outside and through the network conductor 11 is connected to the electric arc furnace transformer. Due to a certain shift of the switching element to a specific input terminal 8 and the corresponding 4 exhaust closes the load circuit reactive ballast units V between point 3 power supply and the output conduit 11. Thus, corresponding to the 4 exhaust reactivity 4 choke coil 1 without ferromagnetic core available on the output conductor 11.
Figure 2 schematically shows a process of switching the switching element 9 of figure 1 between the position of the speed and position of the bridge in the switch phases a to F. using and what the considerations applying phase shift And the first explains in detail the components of the switching element, which are the same for the other switch phases b through F. For clarity, the images switch phases b through F components of the switching element 9 only in cases provided with a reference position, where it is necessary to explain the switching process.
Shown in figure 2, the switching element 9 is connected through switch 2-speed load with Seating for 4 taps choke coil 1 without a ferromagnetic core, as can be seen in figure 1. Presents two inputs 12l, 12r of the switching element 9, which in figure 1 correspond to the input contact 8 of switch 2-speed load. In the view on the drawing, the switching element 9 has a left conductive branch, or branch 13l, conductive or right branch, or branch 13r, which are, respectively, provided with a throttle reels 14l 14r and, respectively, through passages 15l, 15r of contact with the tumblers 16l, 16r is connected to node 17 branching. Node 17 branching leads to the exit 21 of the switching element 9. Accordingly, between the throttle reels 14l, 14r and places 15l, 15r contact has a cross-connection 18 with the vacuum switch 20 between the conductive branches 13l and 13r, which in places 19l, 19r connection, respectively, associated with them. Arrow S indicates the opposite direction of the current.
The switching process is evident from the individual asperuloside with And F:
And the Switching element 9 is in the position of the steps at the entrance 12l. Both branches 13l and 13r is applied to the input of 12l. Tumblers 16l and 16r are in corresponding locations 15l, 15r contact in the closed position, so that both branches 13l and 13r are under load. Choke coils 14l and 14r provide symmetrical load balancing on the branches 13l and 13r.
In - Tumbler 16r is opened, the place 15r contact, the contact is broken. Thus now the cross-connection 18 through a closed vacuum switch is under load.
With the Vacuum switch 20 is opened, the branch 13r free from load and can be shifted, the entire burden falls on the branch 13l.
D - free from the load branch 13r is shifted from input 12l to the entrance 12r.
E - the Vacuum switch 20 is closed, the cross-connection 18 and the branch 13r are once again under load, the position of the bridge is active, as is now the inputs 12l and 12r through node 17 branching install closed circuit.
F - Toggle 16r again locked in place 15r contact is again established contact. The position of the bridge instead of implementing through the cross-connection 18 is implemented through both 15l, 15r of the contact.
In a reverse sequence relative to the sequence from A to F mirror-symmetrically to it can now move the branch 13l to set the position of the stage both ve the Wei 13l and 13r at the entrance 12r.
In this way, using the bridge circuit of the switching element 9 with the formation positions of the bridge on the various inputs may be offset from the position of the stage to the position of the stage between these different inputs under load.
Figure 3 shows an electric arc furnace with the furnace transformer T and reactive ballast V device of the above type with a choke coil 1 and switch 2-speed load.
1. Reactive ballast device (V), for electric arc furnace transformer with point (3) power supply is choke-coil (1), free the switch (2) levels of load and output pin (10), and the choke coil (1) is connected to point (3) power supply, and referred to free the switch (2) speed load is supplied with a certain number of input contacts (8)are connected by a wire with the places (4) bends choke coils (1) and with the switching element (9) switch (2) levels of load, and the output switching element (9) through the output pin (10) leads to the outside and through the network conductor (11) is connected with the electric arc furnace transformer, switch (2) speed load is made with possibility of installation of reactivity choke coils (1) under load.
2. Reactive ballast device (V) according to claim 1, and the choke coil (1) is Ipanema as free, with dry insulation choke coil without a ferromagnetic core.
3. Reactive ballast device (V) according to claim 1, and the choke coil (1) is provided with a certain number of seats (4) drainage, which corresponds to a certain number of turns of the choke coil (1).
4. Reactive ballast device (V) according to claim 1, and the choke coil (1) is designed as a free, dry insulation choke coil without a ferromagnetic core, with choke coil (1) is provided with a certain number of seats (4) drainage, which corresponds to a certain number of turns of the choke coil (1).
5. Reactive ballast device (V) according to claim 1, with the switch (2) speed load includes a number of input contacts (8), at least one output pin (10) and the switching element (9), while the switching element (9) is arranged to connect at least one input pin (4) with output contact (10)and the reservoir (6) with insulating means, and a reservoir (6) is made with the possibility of placing him in a switching element (9).
6. Reactive ballast device (V) according to claim 5, and a switching element (9) contains a number of inputs (121, 12r) and at least one outlet (21), and one or each output of correlated node (17) branching, with whom which are connected, at least two branches (131, 13r) of the bridge circuit, and the branches (131, 13r), respectively, are deactivatable in the inclusion (151, 15r), and branch (131, 13r), respectively, scalable way connected with the inputs (121, 12r) and, respectively, are pairwise interconnected through a cross-connection (18) is connected with the seat (20) enable load/ in particular, the vacuum switch.
7. Reactive ballast device (V) according to claim 1, and the choke coil (1) is provided with a certain number of seats (4) allocation, and the switch (2) speed load includes a number of input contacts (8), at least one output pin (10) and the switching element (9), while the switching element (9) is arranged to connect at least one input pin (4) with output contact (10)and the reservoir (6) with insulating means, and tank (6) is made with the possibility of placing him in a switching element (9), and the number of seats (4) bends choke coils (1) coincides with the number of input contacts (8) switch (2) levels of load and, consequently, (4) connection is connected to the input pin (8).
8. Reactive ballast device (V) according to claim 1, and the choke coil (1) is provided with a certain number of seats (4) drainage, while the switching element (9) contains some of the second number of inputs (121, 12r) and at least one outlet (21), and one or each output of correlated node (17) branching, which incorporate at least two branches (131, 13r) of the bridge circuit, and the branches (131, 13r), respectively, are deactivatable in the inclusion (151, 15r), and branch (131, 13r), respectively, scalable way connected with the inputs (121, 12r) and, respectively, are pairwise interconnected through a cross-connection (18) is connected with the seat (20) turn on the load, in particular, the vacuum switch, and the number of seats (4) bends choke coils (1) coincides with the number of input contacts (8) switch (2) levels of load and, consequently, (4) connection is connected to the input pin (8).
9. Reactive ballast device (V) according to claim 7 or 8, and the input (8) and outputs (10) switch speed load unambiguously correlated with the corresponding inputs (121, 12r) and outputs (A) a switching element.
10. Transformer (T), in particular, for electric arc furnace (Of), designed to connect before him a reactive ballast device (V) according to claim 1 for installation reactivity.
11. Transformer (T) in paragraph 10, and the transformer has an optional device for installation reactivity with a choke coil and switch the speed of the load.
12. Electric arc furnace (O), in which lastnosti, for smelting steel, is connected to the transformer (T) PP or 11.
FIELD: electrical engineering.
SUBSTANCE: three-phase electric arc furnace (1) power supply installation has at least one furnace transformer (4) connected to the three-phase electric arc furnace (1) on the output side. On the input side, the transformer (4) is connected to the three-phase feeder mains (3) via the double-link AC converter (5). The double-link AC converter (5) has at least one rectifier (6) on the mains side, at least one inverter (7) on the transformer side and an intermediary AC link (8) between the rectifier (6) and the inverter (7). Each phase of the three-phase feeder mains (3) is connected, via the rectifier (6) two converter elements (11) to the intermediary AC link (8). Each phase of the furnace transformer (4) input side is connected, via the inverter (7) two converter elements (12) to the intermediary AC link (8).
EFFECT: reduction of the furnace operation interference with the feeder mains and independence of the number of phases and the furnace operational frequency from the feeder mains.
18 cl, 4 dwg
SUBSTANCE: control method of ore-heating furnace operating mode for producing zirconia alumina involves measurement of voltage and current during melting, control of feeding the charge and degree of the electric arc development. Also, the value of the constant component of the phase voltage of each electrode is measured, then it is compared to a predetermined optimum value and in case of deviation from a set point the electric mode or dosage of the charge is adjusted to eliminate the deviation of the values of the constant component of phase voltage.
EFFECT: stabilisation of the melting process.
SUBSTANCE: invention refers to transformer system (1) for electric arc furnace (2) with three electrodes (202) where transformer system (1) contains at least two three-phase transformers. Three-phase transformers (100) in this system are connected in parallel with electrodes (202) and are energised or respectively deenergised depending on each other and are operated synchronously.
EFFECT: increase in arc furnace power.
14 cl, 4 dwg
SUBSTANCE: device for control of white alumina melting in electroarc furnace contains electrostatic precipitator implemented with ability of extraction of constant component of furnace voltage, comparator unit, current probe in electrodes. Device is outfitted by two summator, sensor of stages switching of voltage of transformer and microprocessor, herewith on inlets of the first summator there are connected electrostatic precipitator, current sensor in electrodes and sensor of switching of voltage stages of transformer voltage. Outlet of the first summator is connected to the first inlet of comparator, the second inlet of which is connected to microprocessor and outlets-to movement mechanism of electrodes and mechanism of stages switching of transformer voltage, outlets of the second summator are connected to current sensor in electrodes and sensor of stages switching of transformer voltage, and its outlet is connected to metering device of charge.
EFFECT: improvement of quality of received product.
FIELD: electrical engineering.
SUBSTANCE: inverter transformer has one primary and two secondaries connected in either series or parallel, each being connected to its appropriate rectifier. Outputs of both rectifiers are connected in parallel with welding electrodes. Note here that one of secondaries is rated at maximum current of electrical load and low voltage of sustaining arcing, while the other one, alone or with the first one that provides arc firing voltage, features minimum power. NC-contacts of direct-action thermal relay are connected to its circuit in series with adjusting resistor with partial or complete shunting of blow motor winding.
EFFECT: lower costs, rated power, weight and overall dimensions; higher efficiency, welding quality and reliability.
FIELD: electric measurement technology; electric-arc furnaces including ore heating and steel smelting furnaces and heating ovens.
SUBSTANCE: proposed method for measuring heavy AC current in bus assembly of furnace-transformer short network includes disposition of at least one magneto-sensing component incorporated in current sensor design interacting with magnetic field set up by current carried by buses and connection of current sensor leads to measuring device; heavy current being measured is passed through opposing buses or bus sections in opposite directions. Sensor has at least one magneto-sensing component placed in space between specularly disposed surfaces of buses and provided with one or more turns of electricity conducting material placed in space so that turn planes are approximately perpendicular to specularly disposed bus planes and approximately parallel to current flow direction in bus. Sensor can be wound on nonmagnetic or ferromagnetic linear core. Desired quantity of magneto-sensing components in system is found from equation where K is total number of magneto-sensing components incorporated in sensor; qi is quantity of magneto-sensing components installed in ith space; n is quantity of bus pairs in bus assembly; ; magneto-sensing components are interconnected in series or in parallel; measuring device has unit for matching signal picked off sensor with characteristic of measuring device input circuits.
EFFECT: facilitated heavy-current measurement procedure, improved design of sensor and measuring system.
24 cl, 12 dwg, 1 tbl
FIELD: AC gas-shield welding by means of coated electrodes and non-consumable electrode.
SUBSTANCE: apparatus includes single-phase welding transformer, pulse generator, step-up transformer. Primary winding of step-up transformer is connected to outlet of pulse generator. Apparatus also includes discharge capacitor, spark gap, welding load, diode and choke. First terminal of secondary winding of step-up transformer, discharge capacitor and choke is connected with first terminal of secondary winding of single-phase welding transformer. Spark gap is arranged between second terminal of discharge capacitor and second terminal of choke. Second terminal of choke through welding load is connected with second terminal of secondary winding of single-phase welding transformer. Inlet of pulse generator is connected with primary winding of single-phase welding transformer. Diode is connected between second terminal of secondary winding of step-up transformer and second terminal of discharge capacitor.
EFFECT: increased value of spark gap and energy of spark discharge at the same power and size of step-up transformer.
3 cl, 1 dwg
SUBSTANCE: invention relates to a manual drive for stepwise control of a step transformer winding tap changer with a locking device, without power consumption. Besides, there is a master shaft, on which per one change there are several manual rotations implemented. There is also a control mechanism, which converts these rotations exactly into one rotation of a geared wheel per one change. The locking mechanism comprises a rotary inner key and a latch rotating around the axis of rotation and a stop, which corresponds to the stop slot of the master shaft, and a stop cam, which corresponds to the slot of the geared wheel of the control mechanism. Due to actuation of the inner key, the latch rotates from the locked position so that the stop and the stop cam are disengaged from the appropriate slots.
EFFECT: higher reliability of protection in respect to undeliberate or deliberate incorrect usage of a manual drive.
7 cl, 10 dwg
FIELD: process engineering.
SUBSTANCE: switching module has, at least, comprises, at least, one switch 2A composed of power semiconductor device, cooling appliance 3A of electrically conducting material and current feed appliance 1A abutting switch 2A whereon abuts switch 2A to cool switch 2A. Insulation means 8A is arranged between cooler 3A and current feeder 1A to isolate cooler 3A from current feeder 1A. Switch 2A, cooler 3A, current feeder 1A and insulator 8A are configured to arranged cooler at no potential which allows decreasing length of coolant feed pipes.
EFFECT: compact design.
11 cl, 2 dwg
FIELD: electrical engineering.
SUBSTANCE: invention relates to a transformer winding stages switch with semiconductor switching elements for continuous switching between the two branches (branch n, branch n+1) of winding of a transformer with staged voltage control each winding branch is connected to the common load output via the corresponding mechanical switch (DS) and a series circuit of two oppositely placed IGBTs (IP, In), the circuit linked in series to the mechanical switch. According to the invention, each IGBT is shunted with a corresponding varistor (Vp, Vn), connected in parallel thereto and calculated in a special way.
EFFECT: no need for special setting to corresponding rated current.
3 cl, 2 dwg
SUBSTANCE: invention relates to the method of breakless switching between two taps (tap n, tap n+1) of a transformer winding with stepped voltage control, besides, each of both winding taps via an appropriate mechanical switch (DS) and a circuit arranged subsequently with it from two opposite IGBT (Ip, In) may be connected with a common loading outlet.
EFFECT: higher functionality.
3 cl, 3 dwg
SUBSTANCE: drive comprises an AC converter-fed motor (1) with permanent magnets, the output shaft (2) of which is connected to a driving shaft (3) of the OLTC device, a programmable logical controller (4), a unit (5) of power switching of the AC converter-fed motor windings (1) with permanent magnets, a sensor (6) of the switching angle of the AC converter-fed motor windings (1), a sensor (7) of position and speed of the AC converter-fed motor (1) shaft, a control panel (8), a panel (9) of OLTC device position indication, a source (10) of uninterrupted supply. The output of the source (10) is connected to the first input of the controller (4), the second input of the controller (4) is connected to the output of the panel (8), its third input is connected to the output of the device for remote control of the OLTC drive, its fourth input is connected to the first output of the unit (5), its fifth input is connected to the output of the sensor 6, its sixth input is connected to the output of the sensor (7), the first output of the controller (4) is connected to the first input of the unit (5), its second output is connected to the input of the panel (9), its third input is connected to the input of the device for remote control of the OLTC drive, the second input of the unit (5) is connected to the source of supply, its third input is connected to the output of the sensor (6), its fourth input is connected to the output of the sensor (7), its second output is connected to windings of the AC converter-fed motor (1), at the same time the sensor (6) and the sensor (7) are placed on the common axis with the AC converter-fed motor (1).
EFFECT: higher operational reliability of the drive, reduced labour intensiveness in manufacturing, higher accuracy of positioning during regulation.
SUBSTANCE: diagnostic system includes measuring device for contacts, which has the possibility of determining the contact position. Contact signal generated with the above measuring device indicated whether the contact is open or closed. Time interval is connected to maximum time during which the contact can be in contact position. Controller has the possibility of receiving the contact signal and generating the time interval if closing on the basis of contact signal and comparison of time interval of closing with threshold time interval in order to determine whether the time closing interval exceeds the threshold time interval. Warning message is generated with diagnostic system and indicates the exceedance of threshold time interval.
EFFECT: reducing the damage to equipment when performing the operations and excluding contact carbonisation.
7 cl, 6 dwg
SUBSTANCE: four-winding three-phase transformer is proposed, three parallel cophased windings of which are made with neutral taps of phases, and six groups of semiconductor diodes connected as a ring, and neutral taps of cophased winding phases are connected to common points between groups of semiconductor diodes in the following sequence: two outputs of phase A, one output of phase C, two outputs of phase B, one output of phase A, two outputs of phase C and one output of phase B, at the same time one of points between semiconductor diodes may be replaced.
EFFECT: reduced dimensions of the device and higher reliability.
3 cl, 1 tbl
SUBSTANCE: compartment (2) of the electric motor within the on-load tap changer comprises an electric motor module and a control module (12). The module of the electric motor comprises an electric motor (6), a reducer (7) and a position sensor (9), besides, the control module (12) is made with the possibility to control an output shaft (3), which goes out from the compartment (2) of the electric motor, by means of power supply to the electric motor (6) via a direct connection to put the output shaft (3) in motion via a reducer (7), besides, the position sensor (9) is made with the possibility to register motion and positions of the output shaft (3) and to transfer information about such to the control module (12). The compartment (2) of the electric motor in the working condition is tightly closed with the electric motor module and the control module (12), arranged inside such tightly closed volume.
EFFECT: reduced time for production deployment, increased flexibility for making changes into the order at the later stages of its completion, increased convenience of service, reduced cost of the electric motor for the on-load tap changer.
7 cl, 2 dwg
SUBSTANCE: transformer comprises two parts, the main (1) one and the additional (2) one arranged on a separate triple-rod core with six windings, three primary and three secondary ones, connected in series and in a cophased manner with according windings of the main part. The additional part has a high turn transformation ratio compared to the main part. Capacitors (3) are serially connected in a circuit of its primary windings. The additional part is arranged on a transformer core, which is 10 times less than the main part. Windings of the additional part have 10-16% of turns quantity compared to the appropriate windings of the main part. Smooth contactless self-control of voltage under load is executed without an extraneous effect at the transformer operation and does not required additional automatics or a person's attendance. In an idle run mode there is a rated voltage available at the outlet of the composite transformer, which gradually increases while the load increases. Control may be voltage stabilisation. The additional part dimensions are determined by a selected value of the voltage growth. The additional part may be added to a transformer in operation.
EFFECT: provision of smooth contactless self-control of voltage under load.
3 cl, 3 dwg
SUBSTANCE: device of smooth AC motor start with initial load, which is considerably lower than the rated value comprises reactors with natural air cooling arranged with the possibility of installation in phase wires, normally open contacts connected in parallel to reactors, and device of contacts control arranged with the possibility of contacts closure after motor current reaches the rated value. Ratio of reactors inductance to their active resistance at room temperature is lower than values of reactors designed for durable operation at the rated current, and which are calculated using found formulas of specified ratio dependence on power of electric motor for situations when ferromagnetic core is available or unavailable in reactors.
EFFECT: reduced dimensions, material intensity and cost.
2 cl, 4 dwg, 3 tbl
FIELD: continuous switching of tap-changing-under-load transformers.
SUBSTANCE: proposed stepping thyristor switch has mechanical stepping selector and load switch. Stepping selector only is disposed in transformer oil tank while load switch incorporating thyristors is mounted in separate case attached to one side wherein it is held in air medium, so that switch thyristors are disposed away from hot transformer oil.
EFFECT: enhanced reliability and service life of switch.