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Presentation on Power Transformer & Distribution Transformer Protection
Detailed transformer protection concepts and with numerical calculation.Description complète
The transformer is an essential part of the transmission and appropriation framework. The point of creating, transformer security structure is to oversee in such a manner, that we are utilizing microcontroller and IoT to give programmed security and
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Power Transformer Protection
Descripción: ABB Transformer Protection
Detailed transformer protection concepts and with numerical calculation.Full description
Detailed transformer protection concepts and with numerical calculation.Descripción completa
Interview Questions is the book which helps in the interviewDescription complète
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Interview Questions on Transformer Protection •
Q. What parameters or technical particulars are important to be considered while designing protection scheme of the transformer? Answer:
1. Netw Network ork Diagram Diagram showi showing ng the positi position on of the trans transform former er in the system system 2. kVA or MVA MVA ratin rating g of the the transf transforme ormerr 3. Fa Fault ult Leve Levell at the the trans transfor former mer 4. Vo Volt ltag agee Rat Ratio io 5. Wi Wind ndin ing g Conn Connec ecti tion onss 6. Pe Perr Uni Unitt Imp Imped edan ance ce 7. Ne Neutr utral al Point Point Earthi Earthing ng Resist Resistanc ancee 8. Val Value ue of the the System System Eart Earthing hing Resis Resistanc tancee 9. Wh Wheth ether er Indo Indoor or or or Outd Outdoor oor 10. Dry or Oil Filled Filled 11. Length and area area of cross section section of the connecting connecting leads between between CTs and Relay Panel •
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Q. What can be the reasons for the failure of the transformer? Answer: Transformer Transform er is one of the most expensive equipments in the Power System. Failure of the transformer can cause outage of power supply for even days. However, multiple things can go wrong with the transformer: There can be two types of failure - Internal Faults and External Faults. Internal Faults (the faults within the transformer):
1. Co Corre Fai ailu lurre 2. Wi Wind ndin ing g Fail Failur uree 3. La Lami mina nati tion on Fai Failu lure re 4. Bu Bush shin ing g Fa Fail ilur uree 5. Ter Termin minal al Boa Board rd Fa Failu ilure re 6. Tap Chan Changer ger Fail Failure ure (OLT (OLTC C failur failures) es) 7. Tr Tran ansf sfor orme merr Oil Oil 8. Oil le leve vell lo low w 9. Mo Mois istu ture re abso absorp rpti tion on 10. Transform Transformer er cooling system 11. Failure of insulation between between Lamination Lamination and Core Bolt 12. Badly made joints and connection connections. s. 13. Frequent exposure exposure to Lightning Lightning strokes strokes •
External Faults (the faults outside the transformer):
1. OverLoad OverLoad ... increa increases ses copper copper losses losses and and consequen consequence ce temperat temperature ure rise. rise. 2. Through Faults or System System Faults Faults ... ... not detected by differential differential protection protection of transformer, however, if through faults persist for longer duration, transformer gets damaged by thermal and electromagnetic mechanical stress ... detected by overcurrent relays. 3. Sh Shor ortt Cir Circu cuit itss
4. 5. 6. 7.
Open Circuits Earth Faults Over Voltage Reduced system frequency
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Q. How Transformer Protection provided for internal faults? Answer:
1. Bucholz Relay (1st Stage Alarm and 2nd Stage Trip) 2. Sudden Pressure Relay (1st Stage Alarm and 2nd Stage Trip) 3. Pressure Relief Valve (1st Stage Alarm and 2nd Stage Trip) 4. Pressure Switch (1st Stage Alarm and 2nd Stage Trip) 5. Oil level Gauge Indicator (Alarm) 6. Vacuum Level Indicator (Alarm) 7. Oil Temperature Indicator (Alarm) 8. Gas Temperature Indicator (Alarm) 9. Silicon Breather (Passive - no alarm) 10. Smoke Detector (Alarm) •
Q. How Transformer Protection provided for external faults? Answer:
1. 2. 3. 4. 5. 6. 7.
Differential Protection Restriced EarthFault Protection Over Current Protection Over Fluxing Protection Over current relays with under voltage blocking Zero sequence protection. Negative phase sequence protection
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Q. What are the tests done to minimize internal faults? Answer:
1. Dissolved Gas Analysis (DGA): Faults due to arcing, high current breakdown of oil, localized sparking, partial discharge of oil, localized overheating or hot spots, etc. causes thermal degradation of oil and used for analysis. 2. Thermography of Transformer: Hot Spots on the transformer bushing, circulation of oil in radiator tubes, distribution of heat on transformer body, etc. 3. Capacitance Tan Delta: to detect oil degradation. 4. Oil Sample Test: to check the oil quality. •
1. 2. 3. 4.
Q. What are the reasons for Oil degradation? Answer:
Degradation Oxidation Contamination a) Dielectric breakdown voltage indicates the presence of electrically conductive contaminants in oil.
b) Interfacial tension and acid number (sometimes called neutralization number or acidity) are affected by oxidation and contamination. c) Water content is temperature dependent. d) Power factor is also temperature dependent. •
Q. What protection are provided to transformer depending on their kVA or MVA ratings?
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Protection
Transformer Rated Transformer Rated Transformer Rated below 500 kVA between 500 kVA - above 500 kVA 5MVA
