CN101702361A - Ultra-low frequency alternating-current (AC) constant-current demagnetization device of large transformer or mutual inductor and demagnetization detection method - Google Patents
Ultra-low frequency alternating-current (AC) constant-current demagnetization device of large transformer or mutual inductor and demagnetization detection method Download PDFInfo
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Abstract
The invention relates to an ultra-low frequency alternating-current (AC) constant-current demagnetization device of a large transformer or mutual inductor, comprising a display (1) and a CPU control unit (2), wherein the CPU control unit (2) is connected with a power-frequency signal generator (3); the power-frequency signal generator (3) is connected with a voltage power amplifier (4); the voltage power amplifier (4) is connected with a voltage booster (5); the CPU control unit (2) is also connected with an ultra-low frequency signal generator (6); a switch is arranged between a transformer or a mutual inductor (8) to be tested and the voltage booster (5); and a switch is arranged between the transformer or the mutual inductor (8) to be tested and a current power amplifier (7). The invention overcomes the defects of long demagnetization time, easy transformer coil deformation, and the like of the traditional method and has the advantages of short demagnetization time, light equipment weight, and the like. The invention also discloses a demagnetization detection method adopting the demagnetization device.
Description
Technical field
The present invention relates to a kind of high-power transformer or instrument transformer ultralow frequency and exchange the constant current demagnetizer, the invention still further relates to the demagnetization detection method that adopts this demagnetizer.
Background technology
Transformer or instrument transformer are equipment important in the electric power system, its fail safe and stability are very important to the operation of whole electric power system, during steady operation. the exciting current of transformer has only 1%～2% of its rated current, but after transformer is carrying out the D.C. resistance test, will produce very big magnetizing inrush current when closing a floodgate once more.Its peak value can reach the tens of to hundred times of rated current, if the remanent magnetism of transformer is big, the attenuation ratio of this transient current is slower, and before arriving stable state, its general sustainable several seconds was by tens of seconds.This operation to transformer is totally unfavorable, and this magnetizing inrush current can cause the malfunction of transformer relay protecting system or make Transformer Winding produce the displacement distortion, or the insulation of transformer is degenerated.
At present demagnetizing method has two kinds of heat demagnetization and AC demagnetizations.1., heat demagnetization is that sample is heated to more than the Curie point, slow cool to room temperature under no condition of external field then.Though this method operating process is complicated, may cause sample structure to change, the effect that it can obtain to demagnetize fully, this method obviously are not suitable for transformer and instrument transformer demagnetization.2., AC demagnetization is to add an alternating magnetic field on sample, and makes its amplitude evenly be reduced to zero by a certain maximum.AC demagnetization is divided into the AC demagnetization under alternation direct current demagnetization and the power frequency.The alternation direct current demagnetization is by means of magnetization cycle is first the sample magnetic saturation to be commutated with current reverser then, simultaneously demagnetization current is reduced to zero.The demagnetization process of this method is difficult for being consistent, and the magnetization curve start-up portion that records has than big difference.Still extensively adopting at present the AC demagnetization method under the power frequency, but the time that the method needs is long, equipment is huge, operates also very complicated.Power department after carrying out DC experiment generally by directly powering up or adopt the resonance test mode to demagnetize; the method demagnetization time is long; approximately 7-8 hour; also cause the relevant relaying protection action of transformer easily; simultaneously because directly close a floodgate can the powerful surge impact of generation, cause deformation of transformer winding etc. influential to transformer's life span.
Summary of the invention
The objective of the invention is to overcome above-mentioned existing disadvantages of background technology part, and provide a kind of high-power transformer or instrument transformer ultralow frequency to exchange the constant current demagnetizer.
Another object of the present invention is to adopt above-mentioned ultralow frequency to exchange the demagnetization detection method that the constant current demagnetizer is used to detect demagnetization effectiveness.
The objective of the invention is to reach by following measure: high-power transformer or instrument transformer ultralow frequency exchange the constant current demagnetizer, it comprises display, the CPU control unit, it is characterized in that described CPU control unit is connected with the power frequency component generator, described power frequency component generator is connected with the voltage power amplifier, the voltage power amplifier is connected with voltage booster, described CPU control unit also is connected with Signal Generator of Ultra-low Frequency, described Signal Generator of Ultra-low Frequency is connected with current power amplifier, described voltage booster all is connected with tested transformer or instrument transformer with current power amplifier, described voltage booster is connected with the CPU control unit, described tested transformer or instrument transformer are connected with the CPU control unit, between described tested transformer or instrument transformer and the voltage booster switch is arranged, between described tested transformer or instrument transformer and the current power amplifier switch is arranged.
Described power frequency component generator is made up of square wave and sinusoidal wave data table, 8 to 16 Bits Serial DA and low-frequency filter, described square wave and sinusoidal wave data table and 8 to 16 Bits Serial DA, and 8 to 16 Bits Serial DA are connected with low-frequency filter.
Described voltage power amplifier is made up of forward voltage amplifying unit, voltage power amplifying unit and constant voltage feedback control unit, described forward voltage amplifying unit is connected with the voltage power amplifying unit, voltage power amplifying unit and constant voltage feedback control unit, the constant voltage feedback control unit is connected with the forward voltage amplifying unit.
Described Signal Generator of Ultra-low Frequency is made up of square wave and sinusoidal wave data table, 8 to 16 Bits Serial DA and low-frequency filter, described square wave and sinusoidal wave data table and 8 to 16 Bits Serial DA, and 8 to 16 Bits Serial DA are connected with low-frequency filter.
Described current power amplifier is made up of preposition current amplification unit, current power amplifying unit and constant current feedback control unit, described preposition current amplification unit is connected with the current power amplifying unit, the current power amplifying unit is connected with the constant current feedback control unit, and the constant current feedback control unit is connected with preposition current amplification unit.
Adopt the demagnetization detection method of the described demagnetizer of above-mentioned arbitrary claim, it is characterized in that it comprises the steps:
When 1. using, the 50Hz AC signal of an AC400V of present device output adds to tested transformer, detects the no-load current of this moment, and notes this electric current;
2. the low frequency constant-current source is added to tested transformer, electric current is from 10A, finishes when being decremented to 0.05A by 5% speed successively, and this is a demagnetization cycle.
3. add AC400V voltage to tested transformer once more, detect no-load current, and compare,, then note this electric current if the electric current of ratio last time is little with the last time;
4. carry out the next demagnetization cycle, till the no-load current of twice detection of direct current was constant, then thinking demagnetizes finished.
The present invention mainly is dc constant current power supply (or the ultralow frequency AC constant-current source by alternation, frequency is 0.1Hz or lower), control accurately by constant-current source (or ultralow frequency AC constant-current source) this alternation, high-power transformer or current transformer are demagnetized, the iron core magnetization that eliminating transformer or current transformer because DC experiment etc. causes, and by adding alternating voltage, its no-load current is detected, to determine whether its demagnetization finishes, usually only carry out to make remanent magnetism reach perfect condition two to three times about 10 minutes consuming time.
Because the use of this equipment, can significantly reduce high-power transformer or current transformer after finishing DC experiment, the direct surge impact that closes a floodgate and bring, reduced of the impact of combined floodgate surge current to the coil and the magnetic core of transformer, avoided Transformer Winding because the distortion that the combined floodgate surge causes, simpler than traditional demagnetizing method, equipment volume also very little (less than 5kg).Avoid the magnetizing inrush current impact and the important role that put into operation safely to protecting power transformer and instrument transformer.
Description of drawings
Fig. 1 exchanges the structural representation of constant current demagnetizer for high-power transformer of the present invention or instrument transformer ultralow frequency.
Embodiment
Describe performance of the present invention in detail below in conjunction with accompanying drawing, but they do not constitute limitation of the invention, simultaneously by illustrating that advantage of the present invention will become clear more and understanding easily.
Described power frequency component generator 3 is made up of square wave and sinusoidal wave data table 31,8 to 16 Bits Serial DA32 and low-frequency filter 33, described square wave and sinusoidal wave data table 31 and 8 to 16 Bits Serial DA32, and 8 to 16 Bits Serial DA32 are connected with low-frequency filter 33.
Described voltage power amplifier 4 is made up of forward voltage amplifying unit 41, voltage power amplifying unit 42 and constant voltage feedback control unit 43, described forward voltage amplifying unit 41 is connected with voltage power amplifying unit 42, voltage power amplifying unit 42 and constant voltage feedback control unit 43, constant voltage feedback control unit 43 is connected with forward voltage amplifying unit 41.
Described Signal Generator of Ultra-low Frequency 6 is made up of square wave and sinusoidal wave data table 61,8 to 16 Bits Serial DA62 and low-frequency filter 63, described square wave and sinusoidal wave data table 61 and 8 to 16 Bits Serial DA62, and 8 to 16 Bits Serial DA62 are connected with low-frequency filter 63.
Described current power amplifier 7 is made up of preposition current amplification unit 71, current power amplifying unit 72 and constant current feedback control unit 73, described preposition current amplification unit 71 is connected with current power amplifying unit 72, current power amplifying unit 72 is connected with constant current feedback control unit 73, and constant current feedback control unit 73 is connected with preposition current amplification unit 71.
What the present invention will solve is two problems: one is demagnetization, and whether another is to detect to demagnetize to finish.
The principle of demagnetization mainly is to become constant-current source by the direct current signal of an alternation of single-chip microcomputer generation or the sine wave of a 0.1-0.02Hz through after the power amplification, and its amplitude is from 0-10.00A or bigger, and is adjustable continuously.
The principle that detects the standard that whether arrives of demagnetizing is: if the iron core of transformer is magnetized, then its no-load current must increase, change by the electric current that detects between twice demagnetization, or compare, know promptly whether remanent magnetism withdraws to finish with producer the dispatch from the factory no-load current of report.This detects the power frequency component that is produced a 50Hz by single-chip microcomputer, boosts to 400V after power amplification, uses as detection resources to get final product.
During use, the 50Hz AC signal of an AC400V of present device output, add to tested transformer, detect the no-load current of this moment, and note this electric current, and then the low frequency constant-current source being added to tested transformer, electric current is from 10A, finish when being decremented to 0.05A by 5% speed successively, this is a demagnetization cycle.Add AC400V voltage to tested transformer once more, detect no-load current, and compare with the last time, if littler, then note this electric current, and carry out the next demagnetization cycle than last electric current, till the no-load current of twice detection of direct current was constant, then thinking demagnetizes finished.
Claims (6)
1. high-power transformer or instrument transformer ultralow frequency exchange the constant current demagnetizer, it comprises display (1), CPU control unit (2), it is characterized in that described CPU control unit (2) is connected with power frequency component generator (3), described power frequency component generator (3) is connected with voltage power amplifier (4), voltage power amplifier (4) is connected with voltage booster (5), described CPU control unit (2) also is connected with Signal Generator of Ultra-low Frequency (6), described Signal Generator of Ultra-low Frequency (6) is connected with current power amplifier (7), described voltage booster (5) all is connected with tested transformer or instrument transformer (8) with current power amplifier (7), described voltage booster (5) is connected with CPU control unit (2), described tested transformer or instrument transformer (8) are connected with CPU control unit (2), between described tested transformer or instrument transformer (8) and the voltage booster (5) switch is arranged, between described tested transformer or instrument transformer (8) and the current power amplifier (7) switch is arranged.
2. high-power transformer according to claim 1 or instrument transformer ultralow frequency exchange the constant current demagnetizer, it is characterized in that power frequency component generator (3) is made up of square wave and sinusoidal wave data table (31), 8 to 16 Bits Serial DA (32) and low-frequency filter (33), described square wave and sinusoidal wave data table (31) and 8 to 16 Bits Serial DA (32), 8 to 16 Bits Serial DA (32) are connected with low-frequency filter (33).
3. high-power transformer according to claim 1 or instrument transformer ultralow frequency exchange the constant current demagnetizer, it is characterized in that described voltage power amplifier (4) is made up of forward voltage amplifying unit (41), voltage power amplifying unit (42) and constant voltage feedback control unit (43), described forward voltage amplifying unit (41) is connected with voltage power amplifying unit (42), voltage power amplifying unit (42) and constant voltage feedback control unit (43), constant voltage feedback control unit (43) is connected with forward voltage amplifying unit (41).
4. high-power transformer according to claim 1 or instrument transformer ultralow frequency exchange the constant current demagnetizer, it is characterized in that (6 are made up of square wave and sinusoidal wave data table (61), 8 to 16 Bits Serial DA (62) and low-frequency filter (63) Signal Generator of Ultra-low Frequency, described square wave and sinusoidal wave data table (6) 1 and 8 to 16 Bits Serial DA (62), 8 to 16 Bits Serial DA (62) are connected with low-frequency filter (63).
5. high-power transformer according to claim 1 or instrument transformer ultralow frequency exchange the constant current demagnetizer, it is characterized in that current power amplifier (7) is made up of preposition current amplification unit (71), current power amplifying unit (72) and constant current feedback control unit (73), described preposition current amplification unit (71) is connected with current power amplifying unit (72), current power amplifying unit (72) is connected with constant current feedback control unit (73), and constant current feedback control unit (73) is connected with preposition current amplification unit (71).
6. adopt the demagnetization detection method of the described demagnetizer of above-mentioned arbitrary claim, it is characterized in that it comprises the steps:
1., the 50Hz AC signal of an AC400V of demagnetizer of the present invention output, add to tested transformer, detect the no-load current of this moment, and note this electric current;
2., the low frequency constant-current source is added to tested transformer, electric current is from 10A, finishes when being decremented to 0.05A by 5% speed successively, and this is a demagnetization cycle.
3., add AC400V voltage to tested transformer once more, detect no-load current, and compare,, then note this electric current if littler than last electric current with the last time;
4., carry out the next demagnetization cycle, till the no-load current of twice detection of direct current is constant, then thinking the demagnetization finishes.
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| CN2009102727698A CN101702361B (en) | 2009-11-17 | 2009-11-17 | Ultra-low frequency alternating-current (AC) constant-current demagnetization device of large transformer or mutual inductor and demagnetization detection method |
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| CN2009102727698A CN101702361B (en) | 2009-11-17 | 2009-11-17 | Ultra-low frequency alternating-current (AC) constant-current demagnetization device of large transformer or mutual inductor and demagnetization detection method |
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| CN101702361B CN101702361B (en) | 2011-08-10 |
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