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Transformer
Transformer
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Transformer

  1. 1. STUDY OF TRANSFORMER SUBMITTED TO:- submitted by:- Padmadhar Garg 1
  2. 2. Transformer 2
  3. 3. Transformer A transformer is a device that transfers electrical energy from one circuit to another through inductively coupled electrical conductors 3
  4. 4. If a load is connected to the secondary circuit, electric charge will flow in the secondary winding of the transformer and transfer energy from the primary circuit to the load connected in the secondary circuit 4
  5. 5. The secondary induced voltage VS, of an ideal transformer, is scaled from the primary VP by a factor equal to the ratio of the number of turns of wire in their respective windings: 5
  6. 6. By appropriate selection of the numbers of turns, a transformer thus allows an alternating voltage to be stepped up — by making NS more than NP — or stepped down, by making it less. 6
  7. 7. Type Of Transformer: 1. Shell Type Transformer 2. Core Type Transformer 7
  8. 8. TRANSFORMERS RULES Transformer is based on two principles: Firstly,that an electric current can produce a magnetic. Secondly, electromegnetic induction 8
  9. 9. An ideal step- down transformer showing magnetic flux in the core. The primary and secondary coils are wrapped around a core of very high magnetic permeability,such as iron. PRACTICAL CONSIDERATION 9
  10. 10. Induction law Faraday’s law states that: Vs=Ns.dΦ/dt where VS is the instantaneous voltage. NS is the number of turns in the secondary coil. 10
  11. 11. Since the same magnetic flux passes through both the primary and secondary coils in an ideal transformer,the instantaneous voltage across the primary coil Vp=Np.dΦ/dt 11
  12. 12. Taking the ratio of the two equationsTaking the ratio of the two equations forfor VSVS andand VPVP gives the basicgives the basic equation for stepping up or steppingequation for stepping up or stepping down the voltagedown the voltage 12
  13. 13. If Ns>Np, Vs>Vp Such transformer voltage across secondary is greater than primary voltage called step up transformer. Voltage cross secondary less than primary voltage called step down transformer. 13
  14. 14. Types of Transformers: A wide variety of transformer designs are used for different applications. Some important types are given as: Power transformer Distribution transformer Instrument transformers Auto-transformer  Resonant transformer 14
  15. 15. Ideal Transformer The primary and secondary winding should have zero resistance.It means there is no ohmic power loss and no resistive voltage drop. There is no stray capacitance through the actual transformer.It has inter-turn capacitance and capacitance between turns and ground but their effect is negligible at 50 Hz. 15
  16. 16. Continue… • There is no leakage flux so that all the flux is confined to the core and links both the windings. • The core has infinite permeability so that zero magnetizing current is needed to establish the requisite amount of flux in the core. • The core loss (the hysteresis as well as current loss) is considered zero. 16
  17. 17. DISTRIBUTION TRANSFORMER • TRANSFORMER WHICH IS USED FOR THE PURPOSE OF DISTRIBUTION OF POWER. • 11KV/433V is the standard voltage rating. • STANDARD KVA ratings are 25,63,100,160,200,250,315,400,500,630,750 , 1000 , 1250,1500,2000,2500 KVA. IS-2026 is the NATIONAL I S STANDARD. 17
  18. 18. Transformers in MNIT Location Rating Girls Hostel 500KVA Boys Hostel 500+500KVA Design centre 500KVA Admin. Block 500KVA Canteen 500KVA Pump house 100KVA Colony I 315KVA Colony II 250KVA Sports 250KVA Workshop 250KVA Electrical Dept. 500KVA Hostel Canteen 315KVA Hostel 5 500KVA Hostel 6 315KVA Hostel 5 160KVA 18
  19. 19. Transformer testing I. Short Circuit Test II. Open Circuit Test III. Sumpner’s Test IV. Polarity Test 19
  20. 20. Transformer Losses There are mainly two kinds of losses in a transformer namely • I. Core Loss (constant loss) • II. Ohmic Loss (variable loss) 20
  21. 21. Transformer Efficiency 21
  22. 22. Transformer Rating 22
  23. 23. Efficiency Calculation: 23
  24. 24. 24
  25. 25. TRANSFORMER AUDIT FORM transformer_basic_audit_form.pdf 25
  26. 26. MAINTENANCE PROCEDURE • OIL : 1. Oil level checking. Leakages to be attended. 2. Oil BDV & acidity checking at regular intervals. If acidity is between 0.5 to 1mg KOH, oil should be kept under observation. 3. BDV, Color and smell of oil are indicative. 26
  27. 27. CONTINUE… 1. Sludge, dust, dirt ,moisture can be removed by filtration. 2. Oil when topped up shall be of the same make. It may lead to sludge formation and acidic contents. • Insulation resistance of the transformer should be checked once in 6 months. • Megger values along with oil values indicate the condition of transformer. • Periodic Dissolved Gas Analysis can be carried out. 27
  28. 28. • Periodic checking of any loose connections of the terminations of HV & LV side. • Breather examination. Dehydration of Silica gel if necessary. • Conservator to be cleaned from inside after every three years. • Regular inspection of OIL & WINDING TEMPERATURE METER readings. • Cleanliness in the Substation yard with all nets, vines, shrubs removed. CONTINUE… 28
  29. 29. THANKS!!! 29

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