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Transformer basic

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transformer protection, transformer BDV value

transformer protection, transformer BDV value

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  • 1. Transformer Basic-B. PrasadCharteredEngineeramieclub@gmail.com
  • 2. working principle A transformerworks on theFaraday,slawofelectromagnetic induction.A transformerconsists of alaminatedmagnetic
  • 3. Transformerparts
  • 4. Winding
  • 5. Type of transformer Distribution Power. Control. Auto. Isolation. Instrument potential. Instrument current Indoor Outdoor Oil type Dry type Core type Shell type Natural cool Forced air/watercool
  • 6. Distribution transformerPrimaryvoltageSecondaryvoltageCapacity(KVA)Construction Impedancerange3-11 380-440 25,40,63 Dry type 3-7%100,150,250 Dry type300,400,500 Oil/dry type630,750,1000 Oil type1250,1600 Oil type2000,2500 Oil type
  • 7. Star delta connection
  • 8. Star delta diagram
  • 9. Star delta voltage current Line voltage on Primary side = √3 X Phase voltage onPrimary side. So Phase voltage on Primary side = Line voltage on Primaryside / √3 Transformation Ration (K) = Secondary Phase Voltage /Primary Phase Voltage Secondary Phase Voltage = K X Primary Phase Voltage. As Secondary  in delta connected: Line voltage on Secondary side = Phase voltage onSecondary side. Secondary Phase Voltage = K X Primary Phase Voltage.=K X (Line voltage on Primary side / √3)
  • 10. Advantages of StarDelta Connection The Y-D connection has no problem with thirdharmonic components fewer numbers of turns are required The neutral available on the primary can beearthed to avoid distortion. Neutral point allows both types of loads(single phase or three phases) to be met Large unbalanced loads can be handledsatisfactory
  • 11. Disadvantages of star delta The secondary voltage is not in phase with theprimary If secondary of this transformer should beparalleled with secondary of another transformerwithout phase shift, there would be a problemApplication: commonly employed for power supplytransformers. Y connection on the HV side reduces insulationcosts the neutral point on the HV side can begrounded.
  • 12. Tap changerIt is a device fitted inthe transformer,which is used tovary the voltagetransformationratio. Off load tapchanger Onloadtapchanger(OLTC)
  • 13. BUSHINGTransformer Bushingsare specially designedelectrical terminals fortaking out windingends (leads) throughthe openings providedon the top cover orwall of the oftransformer tank andconnecting to theincoming andoutgoing lines.
  • 14. CT =CURRENTTRANSFORMERTypical specification fora 11kV CT System voltage:11 KV Insulation level voltage (ILV) :12/28/75 kV Ratio: 200/1 - 1 - 0.577 A Core 1: 1A, metering, 15VA/class 1, ISF<10 Core 2: 5A, protection, 15VA/5P10 Short time rating:20 kA for 1second
  • 15. PT=POTENTIALTRANSFORMERTypical specification fora 11 kV VT System voltage: 11 KV Insulation level voltage (ILV) : 12 /28/75 kV Number of phases: Three Vector Group: Star / Star Ratio: 11 kV/ 110 V Burden: 100 VA Accuracy: Class 0.5 Voltage Factor: 1.2 continuous and1.5 for 30 seconds With provision forfuse
  • 16. Condition ForParallel Operation OfTransformers Same voltage and Turns Ratio (both primary andsecondary voltage rating is same) Same Percentage Impedance and X/R ratio Identical Position of Tap changer Same KVA ratings Same Phase angle shift (vector group are same) Same Frequency rating Same Polarity Same Phase sequence
  • 17. TRANSFORMER OILFILTRATION
  • 18. Impedance Levels Based kVA Minimum Impedance, %0 – 150 Manufacturer’s standard151 – 300 4301 – 600 5601 – 2,500 62,501 – 5,000 6.55,001 – 7,500 7.57,501 – 10,000 8.5Above 10,000 9.5
  • 19. Oil and winding temperature indicationDescription Setting, degree CFan start 85Fan stop 75Pump start 90Pump stop 80Oil temperature alarm 85Oil temperature trip 95Winding temperaturealarm100Winding temperature trip 110
  • 20. Transformer protection–  Overcurrent & Short circuit (51):The relay used is CDAG 51. Earth Fault (51N): The relay used is CAG 14. TransformerDifferential (87T): The relay used isDTH 31, 11/6.6KV transformers.  WTI (49WTX/49WAX): protected against increasein winding temperature. The relay used is VAA 34. OTI (49TX/49AX): protected against increase in oiltemperature. The relay used is VAA 34.  Buchholz (63TX/63AX): protected against internal.The relay used is VAA 34.
  • 21. ACT FAST AND INITIATEFIRST बड़ा    सोचो        तेजी से सोचो व    सबसे पहले सोचो िवचारो     पर िकसी का      एकािधकार नही होता.  ----  धीरभाई अमबानी
  • 22. THANK YOU