Prologue to Power Transformer
Power transformer is a principle segment of the force era station. They are generator venture up transformer, station administration transformer, unit helper transformer, power appropriation transformer and numerous more.Range from low voltage transformer 400 Volt, medium voltage transfomer 16 kV, High voltage transformer 150 kV, Extra High voltage transformer 500 kV, and so forth.
Power Transformer component,failure mode, preventive, and prescient support.
1. Transformer LV & HV Bushing
Transformer porcelain bushing is utilized to take the high voltage and low voltage down-lead inside of the transformer out of the oil tank. It is not just the protection to the earth for the down-lead additionally a supporting and altering part. Consequently, the transformer empty encasing must meet the electrical and mechnical quality indicated in the assembling standard.
Center voltage transformer can utilize clay/porcelain bushing separator; high voltage transformer regularly uses oil drenched porcelain bushing and capacitive earthenware bushing protector.
Disappointment Modes
It has long been perceived that bushing disappointments speak to a huge, if not the best, wellspring of transformer and breaker disappointments. The bushings of the best concern are those more prominent than 25kV, which are of the condenser or capacitive sort. These bushings are twisted with capacitive layers which disseminate the electric field quality inside of the bushing evening out it start to finish. These capacitive layers are fixed under oil to secure against dampness and go about as a dielectric and coolant. There are only a couple disappointment modes run of the mill to condenser bushings.
Porcelain damageChips or splits from vandalism may not bring about prompt disappointment but rather bring about inevitable disappointment because of spillage current following over the sheds or through the porcelain.
Contamination ContaminationUsually influencing all bushings just as, substantial defilement can bring about web blanket or following over the porcelain sheds and in the end, flashover.
Disappointment inside capacitive layersThe most normal bushing disappointment happens inside of these capacitive layers as the protection debilitates and current breaks through. This present brings on additional debilitating which brings about more noteworthy spillage current and the bushingeventually falls flat.
Gasket spillage For Oil filled and oil submerged Bushing
Gasket could be nitrile material and for matured bushing the gasket britle. Dampness can enter the bushing when gasket hole and may bring about low dielectric quality of the oil.
The uplifting news is that these disappointments more often than not occurslowly after some time, taking into consideration the inability to be caught and the bushing supplanted preceding the annihilation of the transformer. Costeffective on-line bushing checking has at long last arrived which can be executed to ensure generally the most well-known disappointment of force transformers for under 1% of the transformer price tag
Instructions to continue bushing dependable ;
- Perform routine test when the transformer deenergized. The test incorporate Tan delta test on C1 and C2 (EHV bushing). C1 & C2 worth can be found on the bushing name plate. The quality is as a standart of the estimation. Tan delta result demonstrates wheter the bushing surface broke or not,and dielectric quality in the inward channel protection.
- Inspect oil level at oil level pointer
- Perform bushing cleaning occasionally when the transformer deenergized. I utilized Sakaphen cleaning pasta for cleaning for best result both cleaness and tan delta.
- Perform thermography observing periodically,at minimum once per month. By this way you can see spillage current through bushing encasing surface and lead association condition.
- When you have save cash, introduce bushing on line checking framework that measures bushing force variable. This is all the more for all intents and purposes and no need transformer deenergized when you screen. Instalation is simple. Deenergized one time then Plug the recipient attachment onto bushing tap and unite with the analyzer screen.
Complete disappointment mode descibed on taking after table ;
2. High Voltage & Low Voltage Winding
The windings fit in with the dynamic piece of a transformer, and their capacity is to convey current. The windings are masterminded as tube shaped shells around the center appendage, where every strand is wrapped with protection paper. Copper is today the essential decision as winding material. Notwithstanding dielectric anxieties and warm necessities the windings need to withstand mechanical strengths that may bring about windings substitution. Such powers can show up amid shortcircuits, lightning, shortcircuits in the net or amid a development of the transformer. A deficiency in the windings can happen because of material blames in the cellulose disconnection,
The strong protection in a transformer is cellulose based items, for example, press board and paper. Its capacity is to give dielectric and mechanical detachment to the windings. Cellulose comprises of long chains of glucose rings. At the point when debasement of the cellulose happens these chains get shorter. Level of polymerization (DP) is the normal number of these rings in the chain and shows the state of the paper. New paper has a normal DP number of 1200-1400. A DP under 200 implies that the paper has a poor mechanical quality and may no more withstand short out and other mechanical strengths that show up. The strong protection is the weakest connection in the transformer protection framework, because of the debasement of the cellulose is irreversible and it is regularly not financially solid to supplant it. The maturing of cellulose is quickened by water, oxygen and warmth. An investigation of the paper can tell the dampness content and the DP number of the paper protection. One system for upkeep like degassing/oil separating procedure of the oil likewise diminishes the gas-dampness content in the paper as another balance between the gas-dampness in the oil and in the paper is come to. Keep in mind, Comparison number 1:100. That implies 1 ppm water content in the oil, 100 ppm water content in the cellulose protection.
Step by step instructions to oversee above Phenomena ;
Amid transformer operation ;
- Perform protecting oil observing, for example, ; water content, corrosive number, broke down gas examination (DGA).The interim of testing as maker suggestion, however we do this at regular intervals. On the off chance that ignitable gas rate high, abbreviate the interim for instance like clockwork.
- Perform top oil tank temperature and twisting temperature by transformer on-line checking framework (We utilized Early Warning System, General Electric). Since oil and winding temperature information will help full for breaking down burnable gas happened.
Amid Shutdown :
- Perform winding demonstrative test. They are ; Tan delta test, Megger, Rdc Measurement for every stride OLTC, winding proportion test.
- Perform Sweep recurrence examination test to get winding – center mark.
The following activity ;
- Finding ; ignitable gas rate constantly high for 3 samplings with 3 month interim that implies you have serius issue with your transformer protection. Investigate the reason; over-burdening, warm problem area, low vitality release, sparkle, or arching.You can dissect with some methodes,Roger graph, key gas proportion, or Duval triangle. And after that Plan to purchase new transformer in light of the fact that repairing transformer obliged additional time and you will free more time to deliver electric power as opposed to supplant with new one.
- Finding ; Water content high i.e >30 ppm for my experience and gathered ignitable gas surpasses IEC standart, you need to make oil sifting/degassing at the earliest opportunity. Perform degassing until you find <10 ppm dampness in oil & ignitable gas in traceable quality.
- Finding ; Oil trademark is awful i.e. high corrosiveness, awful shading you need to make oil purging with degassing & dirt treatment.
- Finding ; The consequence of winding analytic shows poor estimation worth, contact transformer merchant or plan to purchase new transformer.I would prefer not to play a diversion with awful protection windin
Power transformer is a principle segment of the force era station. They are generator venture up transformer, station administration transformer, unit helper transformer, power appropriation transformer and numerous more.Range from low voltage transformer 400 Volt, medium voltage transfomer 16 kV, High voltage transformer 150 kV, Extra High voltage transformer 500 kV, and so forth.
Power Transformer component,failure mode, preventive, and prescient support.
1. Transformer LV & HV Bushing
Transformer porcelain bushing is utilized to take the high voltage and low voltage down-lead inside of the transformer out of the oil tank. It is not just the protection to the earth for the down-lead additionally a supporting and altering part. Consequently, the transformer empty encasing must meet the electrical and mechnical quality indicated in the assembling standard.
Center voltage transformer can utilize clay/porcelain bushing separator; high voltage transformer regularly uses oil drenched porcelain bushing and capacitive earthenware bushing protector.
Disappointment Modes
It has long been perceived that bushing disappointments speak to a huge, if not the best, wellspring of transformer and breaker disappointments. The bushings of the best concern are those more prominent than 25kV, which are of the condenser or capacitive sort. These bushings are twisted with capacitive layers which disseminate the electric field quality inside of the bushing evening out it start to finish. These capacitive layers are fixed under oil to secure against dampness and go about as a dielectric and coolant. There are only a couple disappointment modes run of the mill to condenser bushings.
Porcelain damageChips or splits from vandalism may not bring about prompt disappointment but rather bring about inevitable disappointment because of spillage current following over the sheds or through the porcelain.
Contamination ContaminationUsually influencing all bushings just as, substantial defilement can bring about web blanket or following over the porcelain sheds and in the end, flashover.
Disappointment inside capacitive layersThe most normal bushing disappointment happens inside of these capacitive layers as the protection debilitates and current breaks through. This present brings on additional debilitating which brings about more noteworthy spillage current and the bushingeventually falls flat.
Gasket spillage For Oil filled and oil submerged Bushing
Gasket could be nitrile material and for matured bushing the gasket britle. Dampness can enter the bushing when gasket hole and may bring about low dielectric quality of the oil.
The uplifting news is that these disappointments more often than not occurslowly after some time, taking into consideration the inability to be caught and the bushing supplanted preceding the annihilation of the transformer. Costeffective on-line bushing checking has at long last arrived which can be executed to ensure generally the most well-known disappointment of force transformers for under 1% of the transformer price tag
Instructions to continue bushing dependable ;
- Perform routine test when the transformer deenergized. The test incorporate Tan delta test on C1 and C2 (EHV bushing). C1 & C2 worth can be found on the bushing name plate. The quality is as a standart of the estimation. Tan delta result demonstrates wheter the bushing surface broke or not,and dielectric quality in the inward channel protection.
- Inspect oil level at oil level pointer
- Perform bushing cleaning occasionally when the transformer deenergized. I utilized Sakaphen cleaning pasta for cleaning for best result both cleaness and tan delta.
- Perform thermography observing periodically,at minimum once per month. By this way you can see spillage current through bushing encasing surface and lead association condition.
- When you have save cash, introduce bushing on line checking framework that measures bushing force variable. This is all the more for all intents and purposes and no need transformer deenergized when you screen. Instalation is simple. Deenergized one time then Plug the recipient attachment onto bushing tap and unite with the analyzer screen.
Complete disappointment mode descibed on taking after table ;
2. High Voltage & Low Voltage Winding
The windings fit in with the dynamic piece of a transformer, and their capacity is to convey current. The windings are masterminded as tube shaped shells around the center appendage, where every strand is wrapped with protection paper. Copper is today the essential decision as winding material. Notwithstanding dielectric anxieties and warm necessities the windings need to withstand mechanical strengths that may bring about windings substitution. Such powers can show up amid shortcircuits, lightning, shortcircuits in the net or amid a development of the transformer. A deficiency in the windings can happen because of material blames in the cellulose disconnection,
The strong protection in a transformer is cellulose based items, for example, press board and paper. Its capacity is to give dielectric and mechanical detachment to the windings. Cellulose comprises of long chains of glucose rings. At the point when debasement of the cellulose happens these chains get shorter. Level of polymerization (DP) is the normal number of these rings in the chain and shows the state of the paper. New paper has a normal DP number of 1200-1400. A DP under 200 implies that the paper has a poor mechanical quality and may no more withstand short out and other mechanical strengths that show up. The strong protection is the weakest connection in the transformer protection framework, because of the debasement of the cellulose is irreversible and it is regularly not financially solid to supplant it. The maturing of cellulose is quickened by water, oxygen and warmth. An investigation of the paper can tell the dampness content and the DP number of the paper protection. One system for upkeep like degassing/oil separating procedure of the oil likewise diminishes the gas-dampness content in the paper as another balance between the gas-dampness in the oil and in the paper is come to. Keep in mind, Comparison number 1:100. That implies 1 ppm water content in the oil, 100 ppm water content in the cellulose protection.
Step by step instructions to oversee above Phenomena ;
Amid transformer operation ;
- Perform protecting oil observing, for example, ; water content, corrosive number, broke down gas examination (DGA).The interim of testing as maker suggestion, however we do this at regular intervals. On the off chance that ignitable gas rate high, abbreviate the interim for instance like clockwork.
- Perform top oil tank temperature and twisting temperature by transformer on-line checking framework (We utilized Early Warning System, General Electric). Since oil and winding temperature information will help full for breaking down burnable gas happened.
Amid Shutdown :
- Perform winding demonstrative test. They are ; Tan delta test, Megger, Rdc Measurement for every stride OLTC, winding proportion test.
- Perform Sweep recurrence examination test to get winding – center mark.
The following activity ;
- Finding ; ignitable gas rate constantly high for 3 samplings with 3 month interim that implies you have serius issue with your transformer protection. Investigate the reason; over-burdening, warm problem area, low vitality release, sparkle, or arching.You can dissect with some methodes,Roger graph, key gas proportion, or Duval triangle. And after that Plan to purchase new transformer in light of the fact that repairing transformer obliged additional time and you will free more time to deliver electric power as opposed to supplant with new one.
- Finding ; Water content high i.e >30 ppm for my experience and gathered ignitable gas surpasses IEC standart, you need to make oil sifting/degassing at the earliest opportunity. Perform degassing until you find <10 ppm dampness in oil & ignitable gas in traceable quality.
- Finding ; Oil trademark is awful i.e. high corrosiveness, awful shading you need to make oil purging with degassing & dirt treatment.
- Finding ; The consequence of winding analytic shows poor estimation worth, contact transformer merchant or plan to purchase new transformer.I would prefer not to play a diversion with awful protection windin
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