CN104152629A - Method for determining transformer capacity and parameters of refined-smelting ladle furnace under multi-boundary conditions - Google Patents

Method for determining transformer capacity and parameters of refined-smelting ladle furnace under multi-boundary conditions Download PDF

Info

Publication number
CN104152629A
CN104152629A CN201410351147.5A CN201410351147A CN104152629A CN 104152629 A CN104152629 A CN 104152629A CN 201410351147 A CN201410351147 A CN 201410351147A CN 104152629 A CN104152629 A CN 104152629A
Authority
CN
China
Prior art keywords
refining furnace
ladle refining
transformer
capacity
smelting
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
CN201410351147.5A
Other languages
Chinese (zh)
Other versions
CN104152629B (en
Inventor
朱明星
王群京
陈列
摆国睿
高敏
龚光华
武胜奎
高红艳
赵海东
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
XINING SPECIAL STEEL CO Ltd
Anhui University
Original Assignee
XINING SPECIAL STEEL CO Ltd
Anhui University
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by XINING SPECIAL STEEL CO Ltd, Anhui University filed Critical XINING SPECIAL STEEL CO Ltd
Priority to CN201410351147.5A priority Critical patent/CN104152629B/en
Publication of CN104152629A publication Critical patent/CN104152629A/en
Application granted granted Critical
Publication of CN104152629B publication Critical patent/CN104152629B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Landscapes

  • Treatment Of Steel In Its Molten State (AREA)

Abstract

The invention discloses a method for determining transformer capacity and parameters of a refined-smelting ladle furnace under multi-boundary conditions. The method comprises the following steps: calculating and determining capacity of the refined-smelting ladle furnace transformer according to two boundary conditions including molten steel quantity of each refined-smelting ladle furnace and shortest smelting time of each refined-smelting ladle furnace; calculating and determining secondary side voltage range of the refined-smelting ladle furnace transformer according to the three boundary conditions, including the capacity of the refined-smelting ladle furnace transformer, the arc voltage range in the refined-smelting ladle furnace smelting process and the secondary side working current range of the refined-smelting ladle furnace; calculating the PQ operation curve of the refined-smelting ladle furnace by combining the parameters of the power distribution system; and determining whether the transformer is selected reasonably according to the PQ operation curve. The method has the advantages of simple and clear principles and higher accuracy, is easy to operate, and has higher engineering application value.

Description

Ladle refining furnace transformer capacity and determination method for parameter under multi-boundary Condition
Technical field
The present invention relates to a kind of ladle refining furnace transformer, relate in particular to ladle refining furnace transformer capacity and determination method for parameter under a kind of multi-boundary Condition.
Background technology
Ladle refining furnace is to using three-phase alternating current as power supply, utilizes the refining furnace of the energy heating molten steel of electric arc arc light.Electric arc is between three Graphite Electrodess and molten steel ladle, by powerful electric current, to produce on ladle refining furnace.Ladle refining furnace temperature-rise period is to change by electric energy the process that heat energy raises molten steel temperature into, and complete the major equipment that this energy changes, is exactly ladle refining furnace transformer.
In prior art, there is the selection of a lot of ladle refining furnace transformers more chaotic, mostly select by rule of thumb, or use rough formula to carry out quantitative Analysis, cause the transformer of selection reasonable not: 1. when transformer capacity is selected when too small, cause the molten steel heating speed of ladle refining furnace slow, affect rhythm of production; 2. when transformer capacity, select when excessive, cause plant factor to reduce, also increased the investment of equipment simultaneously.Therefore the reasonableness that ladle refining furnace transformer is selected, to ladle refining furnace rationally, economical operation is most important.
Summary of the invention
The object of this invention is to provide ladle refining furnace transformer capacity and determination method for parameter under a kind of easy handling, the more much higher final condition of accuracy.
The object of the invention is to be achieved through the following technical solutions:
Ladle refining furnace transformer capacity and determination method for parameter under multi-boundary Condition of the present invention, comprise step:
The capacity that A, the molten steel amount of smelting according to ladle refining furnace one heat steel and every stove steel the shortest tap to tap time of two final conditions calculated and determined ladle refining furnace transformer;
Three final conditions of scope of capacity, ladle refining furnace smelting process arc voltage scope and the ladle refining furnace secondary side working current of the described ladle refining furnace transformer that B, basis are determined calculate and determine the scope of ladle refining furnace Circuit Fault on Secondary Transformer voltage;
C, definite ladle refining furnace Circuit Fault on Secondary Transformer voltage range is uniformly-spaced divided into a plurality of voltage gears, and determines that permanent power is smelted and the gear of continuous current smelting, in conjunction with the PQ run curve of power distribution system calculation of parameter ladle refining furnace;
D, according to described PQ run curve, in conjunction with power factor, secondary side working current, a plurality of final conditions of transformer capacity, determine whether each voltage gear all exists rational traffic coverage, can determine transformer select whether reasonable.
As seen from the above technical solution provided by the invention, ladle refining furnace transformer capacity and determination method for parameter under the multi-boundary Condition that the embodiment of the present invention provides, the capacity that the molten steel amount of first smelting according to ladle refining furnace one heat steel and every stove steel the shortest tap to tap time of two final conditions calculated and determined ladle refining furnace transformer; Then according to three final conditions of scope of capacity, ladle refining furnace smelting process arc voltage scope and the ladle refining furnace secondary side working current of the described ladle refining furnace transformer of determining, calculate and determine the scope of ladle refining furnace Circuit Fault on Secondary Transformer voltage; Afterwards definite ladle refining furnace Circuit Fault on Secondary Transformer voltage range is uniformly-spaced divided into a plurality of voltage gears, and determines the gear that permanent power is smelted and continuous current is smelted, in conjunction with the PQ run curve of power distribution system calculation of parameter ladle refining furnace; According to described PQ run curve, in conjunction with power factor, secondary side working current, a plurality of final conditions of transformer capacity, determine whether each voltage gear all exists rational traffic coverage, can determine whether transformer selection is reasonable.Principle is simple and clear, easy handling, accuracy are higher, has higher engineering using value.
Accompanying drawing explanation
The schematic flow sheet of ladle refining furnace transformer capacity and determination method for parameter under the multi-boundary Condition that Fig. 1 provides for the embodiment of the present invention;
Fig. 2 is ladle refining furnace power distribution system single line schematic diagram in the embodiment of the present invention;
Fig. 3 is ladle refining furnace electrical operation equivalent circuit schematic diagram in the embodiment of the present invention;
Fig. 4 is ladle refining furnace PQ run curve schematic diagram in the embodiment of the present invention.
Embodiment
To be described in further detail the embodiment of the present invention below.
Ladle refining furnace transformer capacity and determination method for parameter under multi-boundary Condition of the present invention, its preferably embodiment comprise step:
The capacity that A, the molten steel amount of smelting according to ladle refining furnace one heat steel and every stove steel the shortest tap to tap time of two final conditions calculated and determined ladle refining furnace transformer;
Three final conditions of scope of capacity, ladle refining furnace smelting process arc voltage scope and the ladle refining furnace secondary side working current of the described ladle refining furnace transformer that B, basis are determined calculate and determine the scope of ladle refining furnace Circuit Fault on Secondary Transformer voltage;
C, definite ladle refining furnace Circuit Fault on Secondary Transformer voltage range is uniformly-spaced divided into a plurality of voltage gears, and determines that permanent power is smelted and the gear of continuous current smelting, in conjunction with the PQ run curve of power distribution system calculation of parameter ladle refining furnace;
D, according to described PQ run curve, in conjunction with power factor, secondary side working current, a plurality of final conditions of transformer capacity, determine whether each voltage gear all exists rational traffic coverage, can determine transformer select whether reasonable.
In described steps A, the capacity of ladle refining furnace supply transformer calculates by following formula:
In formula: S---the applied power of refining furnace transformer-supplied;
The specific heat capacity of c---molten steel, gets c=0.23kWh/ ℃ of t;
η e---refining furnace power supplying efficiency, get η e=0.85～0.95;
η r---the thermo-efficiency of refining furnace body of heater, get η r=0.4～0.5;
W---Metal Weight, unit: ton;
ν---molten steel temperature rise speed, unit: ℃/min.
The PQ run curve of described ladle refining furnace is corresponding one by one by wattful power, applied power, power factor, short-circuit current and wattless power under each voltage gear of ladle refining furnace.
The PQ run curve of described ladle refining furnace directly indicates the restricted conditions such as the transformer capacity under each voltage gear of ladle refining furnace, power factor, maximum operating currenbt on graphic representation, and what obtain a sealing can traffic coverage scope.
Ladle refining furnace transformer capacity and determination method for parameter under multi-boundary Condition of the present invention, proposed under multi-boundary Condition (ladle refining furnace is to tap to tap time, the smelting steel water yield, arc voltage and working current etc.) and determined capacity and the secondary range of nominal tension of ladle refining furnace transformer, and by setting up PQ model, the reasonableness of selected transformer parameter is verified.Solved existing deficiency in ladle refining furnace transformer chosen process.
The technical solution adopted in the present invention is: the molten steel amount that (1) smelts according to ladle refining furnace one heat steel and every stove steel the shortest tap to tap time temperature rise speed of fast molten steel () two final conditions, calculate and the capacity of definite ladle refining furnace transformer; (2) according to a plurality of final conditions such as scope of the capacity of definite ladle refining furnace transformer, ladle refining furnace smelting process arc voltage (arc length) scope and ladle refining furnace secondary side working current, the scope of calculating definite ladle refining furnace Circuit Fault on Secondary Transformer voltage; (3) definite ladle refining furnace Circuit Fault on Secondary Transformer voltage range is uniformly-spaced divided into a plurality of voltage gears, and determines the gear that permanent power is smelted and continuous current is smelted, in conjunction with the PQ run curve of power distribution system calculation of parameter ladle refining furnace; (4) according to the PQ run curve of simulation calculation, in conjunction with a plurality of final conditions such as power factor, secondary side working current, transformer capacities, determine whether each voltage gear all exists rational traffic coverage, can determine whether transformer selection is reasonable: if 1. each voltage gear all exists rational traffic coverage, transformer is selected rationally; If 2. exist voltage gear without rational traffic coverage, select as the case may be to reduce the magnitude of voltage of high voltage gear or the magnitude of voltage of raising low voltage gear, make each voltage gear all have rational traffic coverage.
Compared with prior art, the invention has the beneficial effects as follows: principle is simple and clear, easy handling, accuracy are higher, has higher engineering using value.
Specific embodiment:
(1) calculating of ladle refining furnace transformer capacity and parameter and checking flow process:
The calculating of ladle refining furnace transformer capacity and parameter and checking flow process are shown in accompanying drawing 1.
(2) according to the temperature rise speed of molten steel amount and molten steel, determine the capacity of furnace transformer:
The relation of ladle refining furnace supply transformer capacity and the smelting steel water yield and temperature rise speed, is shown in following formula.
In formula: S---the applied power of refining furnace transformer-supplied;
The specific heat capacity of c---molten steel, gets c=0.23kWh/ ℃ of t;
η e---refining furnace power supplying efficiency, get η e=0.85～0.95;
η r---the thermo-efficiency of refining furnace body of heater, get η r=0.4～0.5;
W---Metal Weight, unit: ton;
ν---molten steel temperature rise speed, unit: ℃/min.
According to above formula, calculate the different molten steel amount of smelting time electric furnace varying capacity corresponding to each temperature rise speed in Table 5.1.
Electric furnace varying capacity (unit: kVA) corresponding to each temperature rise speed when table 5.1 is smelted different molten steel amounts
Note: smelt power factor 0.9 in table; Power supplying efficiency 90%; Furnace heat efficiency 45%; 0.23kWh/ ℃ of t of molten steel specific heat capacity
By table 5.1, can be found out, for 60 tons of ladle refining furnaces, when the maximum temperature rise speed requiring is 5.5 ℃/min, can select the transformer of 12.5MVA to power.
(3) according to transformer capacity, arc voltage and working current, determine Circuit Fault on Secondary Transformer voltage range:
Ladle refining furnace power distribution system skeleton diagram is shown in accompanying drawing 2, all parameters is all converted to the secondary side of furnace transformer, can obtain refining furnace electrical operation equivalent circuit and see accompanying drawing 3.X in figure s1, iand R s1, ithat conversion becomes the ladle refining furnace 35kV power supply buses system impedance of secondary side voltage range to electric furnace; X s2, iand R s2, ibe to convert the ladle refining furnace 35kV power supply buses of electric furnace change secondary side voltage range to the equivalent impedance between electric arc furnace arc impedance, comprise that 35kV power supply buses is to the circuit equivalent impedance reduced value between arc furnace transformer, arc furnace transformer equivalent impedance reduced value and short net resistance value (noting: do not comprise arc impedance).
According to refining furnace electrical operation equivalent circuit, known refining furnace arc voltage and electric furnace become the relation of rated secondary voltage and flame current and see following formula:
U arc , i = I arc , i × R arc , i R arc , i = U i 2 3 I arc , i - ( X S 1 , i + X S 2 , i ) 2 - R S 1 , i - R S 2 , i - - - ( 5.2 )
Wherein the relation of flame current and short-circuit current is shown below:
I arc , i = k I SC , i , ( k = 0.1,0.2 . . . . . . 0.9 ) I SC , i = U i 3 ( X S 1 , i + X S 2 , i ) 2 + ( R S 1 , i + R S 2 , i ) 2 - - - ( 5.3 )
Suppose to become rated capacity S according to (2) definite refining furnace electric furnace t=12.5MVA, short circuit impedance U d%=9%; 35kV system short circuit capacity S sC, min=400MVA, 35kV bus to the equivalent reactance value that electric furnace becomes is X l=0.032 Ω; Short net reactance X sN=3.5m Ω, short net resistance R sN=0.45m Ω.According to refining furnace electrical operation equivalent circuit, can calculate at different electric furnaces and become under second open circuit voltage, arc voltage corresponding to flame current is in Table 5.2.
The different electric furnace of table 5.2 becomes arc voltage corresponding to flame current under second open circuit voltage
By table 5.2, can be found out, if lock arc voltage between 70V～150V while selecting ladle refining furnace transformer, too low the or too high region of arc voltage in table all should not be selected.The restriction of power supplying efficiency while simultaneously considering electric arc furnace smelting and power factor, flame current during ladle refining furnace real work and the ratio of short-circuit current should not be greater than 70%.In sum, for the refining furnace transformer of this 12.5MVA, its rated secondary voltage should be chosen between 150V～350V.
(4) according to the reasonableness of PQ run curve and the selection of final condition checking electric furnace variable element:
According to above calculating, when ladle refining furnace transformer capacity is 12.5MVA, its rated secondary voltage is selected between 350V～150V.350V～150V is divided into 11 grades, i.e. interval 20V between every two voltage gears, and front four gears is that permanent power is smelted gear, and rear seven gears are that continuous current is smelted gear, and definite transformer parameter is in Table 5.3.
Table 5.312.5MVA electric furnace variable element is selected
According to transformer parameter and ladle refining furnace electrical operation equivalent circuit (accompanying drawing 3), the PQ system of equations of setting up ladle refining furnace as shown in the formula:
P i = 3 I arc 2 ( R S 2 , i + R SN ) Q i = 3 I arc 2 ( X S 2 , i + X SN ) S i = P i 2 + Q i 2 PF = P i / S i - - - ( 5.4 )
According to the PQ equation of ladle refining furnace, draw PQ run curve, see accompanying drawing 4.PQ run curve by ladle refining furnace can be found out, at power factor (0.6～0.95), electric furnace, become under the final condition of secondary side rated current, electric furnace change rated capacity, each voltage gear all has rational traffic coverage, visible, and the selection of electric furnace change secondary voltage rating is proper.
The above; be only the present invention's embodiment preferably, but protection scope of the present invention is not limited to this, is anyly familiar with in technical scope that those skilled in the art disclose in the present invention; the variation that can expect easily or replacement, within all should being encompassed in protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion with the protection domain of claims.

Claims (4)

1. ladle refining furnace transformer capacity and a determination method for parameter under multi-boundary Condition, is characterized in that, comprises step:
The capacity that A, the molten steel amount of smelting according to ladle refining furnace one heat steel and every stove steel the shortest tap to tap time of two final conditions calculated and determined ladle refining furnace transformer;
Three final conditions of scope of capacity, ladle refining furnace smelting process arc voltage scope and the ladle refining furnace secondary side working current of the described ladle refining furnace transformer that B, basis are determined calculate and determine the scope of ladle refining furnace Circuit Fault on Secondary Transformer voltage;
C, definite ladle refining furnace Circuit Fault on Secondary Transformer voltage range is uniformly-spaced divided into a plurality of voltage gears, and determines that permanent power is smelted and the gear of continuous current smelting, in conjunction with the PQ run curve of power distribution system calculation of parameter ladle refining furnace;
D, according to described PQ run curve, in conjunction with power factor, secondary side working current, a plurality of final conditions of transformer capacity, determine whether each voltage gear all exists rational traffic coverage, can determine transformer select whether reasonable.
2. ladle refining furnace transformer capacity and determination method for parameter under multi-boundary Condition according to claim 1, is characterized in that, in described steps A, the capacity of ladle refining furnace supply transformer calculates by following formula:
In formula: S---the applied power of refining furnace transformer-supplied;
The specific heat capacity of c---molten steel, gets c=0.23kWh/ ℃ of t;
η e---refining furnace power supplying efficiency, get η e=0.85～0.95;
η r---the thermo-efficiency of refining furnace body of heater, get η r=0.4～0.5;
W---Metal Weight, unit: ton;
ν---molten steel temperature rise speed, unit: ℃/min.
3. ladle refining furnace transformer capacity and determination method for parameter under multi-boundary Condition according to claim 1 and 2, it is characterized in that, the PQ run curve of described ladle refining furnace is corresponding one by one by wattful power, applied power, power factor, short-circuit current and wattless power under each voltage gear of ladle refining furnace.
4. ladle refining furnace transformer capacity and determination method for parameter under multi-boundary Condition according to claim 3, it is characterized in that, the PQ run curve of described ladle refining furnace directly indicates the restricted conditions such as the transformer capacity under each voltage gear of ladle refining furnace, power factor, maximum operating currenbt on graphic representation, and what obtain a sealing can traffic coverage scope.
CN201410351147.5A 2014-07-22 2014-07-22 Ladle refining furnace transformer capacity and determination method for parameter under multi-boundary Condition Active CN104152629B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201410351147.5A CN104152629B (en) 2014-07-22 2014-07-22 Ladle refining furnace transformer capacity and determination method for parameter under multi-boundary Condition

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201410351147.5A CN104152629B (en) 2014-07-22 2014-07-22 Ladle refining furnace transformer capacity and determination method for parameter under multi-boundary Condition

Publications (2)

Publication Number Publication Date
CN104152629A true CN104152629A (en) 2014-11-19
CN104152629B CN104152629B (en) 2016-08-24

Family

ID=51878253

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201410351147.5A Active CN104152629B (en) 2014-07-22 2014-07-22 Ladle refining furnace transformer capacity and determination method for parameter under multi-boundary Condition

Country Status (1)

Country Link
CN (1) CN104152629B (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108631307A (en) * 2018-05-21 2018-10-09 广东省长大公路工程有限公司 A kind of design method of the tunnel machineization construction scheme of electric power based on drilling and blasting method
CN113740657A (en) * 2021-11-04 2021-12-03 国网江西省电力有限公司电力科学研究院 Method and system for online checking capacity of single high-power-supply high-count distribution transformer

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101833288A (en) * 2009-03-12 2010-09-15 宝山钢铁股份有限公司 Material melting model-based power supply control method for arc furnace
CN103595058A (en) * 2013-10-09 2014-02-19 马钢(集团)控股有限公司 Method for determining capacity of reactive power compensation device of refining furnace
EP2741410A2 (en) * 2012-12-10 2014-06-11 Kabushiki Kaisha Yaskawa Denki Matrix Converter and Method for Controlling Matrix Converter

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101833288A (en) * 2009-03-12 2010-09-15 宝山钢铁股份有限公司 Material melting model-based power supply control method for arc furnace
EP2741410A2 (en) * 2012-12-10 2014-06-11 Kabushiki Kaisha Yaskawa Denki Matrix Converter and Method for Controlling Matrix Converter
CN103595058A (en) * 2013-10-09 2014-02-19 马钢(集团)控股有限公司 Method for determining capacity of reactive power compensation device of refining furnace

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108631307A (en) * 2018-05-21 2018-10-09 广东省长大公路工程有限公司 A kind of design method of the tunnel machineization construction scheme of electric power based on drilling and blasting method
CN113740657A (en) * 2021-11-04 2021-12-03 国网江西省电力有限公司电力科学研究院 Method and system for online checking capacity of single high-power-supply high-count distribution transformer

Also Published As

Publication number Publication date
CN104152629B (en) 2016-08-24

Similar Documents

Publication Publication Date Title
JP6399462B2 (en) AC pressure regulating electronic switch
CN105158540B (en) A kind of arc current evaluation method using electric arc inductance correction factor
CN101615793A (en) The arc furnace idle impact load is to the analytical method of electric network influencing
CN103529265B (en) A kind of ore furnace secondary side Electric Power Measurement System and method
CN104152629A (en) Method for determining transformer capacity and parameters of refined-smelting ladle furnace under multi-boundary conditions
CN203132321U (en) Six-electrode alternating-current submerged arc furnace
CN103595058A (en) Method for determining capacity of reactive power compensation device of refining furnace
CN102542355A (en) Operation planning part load method
CN103631985A (en) Simulation impedance model of electric arc furnace piecewise linearity
CN105406465B (en) A kind of distribution net platform region state analysis method based on load moment nargin
CN101576582B (en) Method for estimating electrode current according to transformer primary side and secondary side ampere-voltage and parameters thereof
CN102593845B (en) Reactive power compensation system of alloy smelting electric furnace system
CN202696150U (en) Electric-arc furnace low voltage side reactive power compensation filtering device
Stopar et al. Electric-arc-furnace productivity optimization
CN203071831U (en) Power supply system for high-power DC (direct current) submerged arc furnace
Ioan et al. Comparative study for EAF's reactive energy compensation methods and power factor improvement
CN106931796A (en) Based on the electrodes in mine hot stove control method for calculating electrode pay(useful) load resistance in stove
Parniani et al. Effects of dynamic reactive compensation in arc furnace operation characteristics and its economic benefits
CN103105053B (en) Six phase electrode alternating submerged arc furnace
CN106208110A (en) A kind of screening technique of distribution network var compensation optimal allocation strategy
CN205160078U (en) Novel hot stove low pressure reactive compensation in ore deposit device
CN215116533U (en) Six-phase unbalance detection system of short net of blast furnace slag carbonization titanium extraction electric furnace
CN203596624U (en) RKEF high-low voltage hybrid compensation device
CN205945084U (en) Three-phase balance circuit of single-phase electroslag furnace
CN205724925U (en) Three-phase load unbalance is automatically adjusted and reactive power compensator

Legal Events

Date Code Title Description
C06 Publication
PB01 Publication
C10 Entry into substantive examination
SE01 Entry into force of request for substantive examination
C14 Grant of patent or utility model
GR01 Patent grant