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TRANSFORMER PPT

  1. STANI MEMORIAL COLLEGE OF ENGG. & TECHNOLOGY,PHAGI JAIPUR -303005 A Ppt Presentation on TRANSFORMER Submitted by RAKESH RAUSHAN 12ESTEE021 Submitted to Abhishek kr. Sharma H.O.D Electrical Department
  2. What is Transformer ?? • A transformer is a electromagnetic static device which is use to convert high alternating voltage to a low alternating voltage and vice versa, keeping the frequency same.
  3. The main principle of operation of a transformer is mutual inductance between two circuits which is linked by a common magnetic flux. A basic transformer consists of two coils that are electrically separate and inductive, but are magnetically linked through a path of reluctance. WORKING OF TRANSFORMER WORKING PRINCIPLE
  4. Construction of Transformer •Basically a transformer consists of two inductive windings and a laminated steel core. The coils are insulated from each other as well as from the steel core. •core is constructed by assembling laminated sheets of steel, with minimum air-gap between them (to achieve continuous magnetic path). •The silicon steel used is to provide high permeability and low hysteresis loss. •Laminated sheets of steel are used to reduce eddy current loss.
  5. Classification of transformer • As per phase 1. Single phase 2. Three phase • As per core 1. Core type 2. Shell type • As per cooling system 1. Self-cooled 2. Air cooled 3. Oil cooled • As per service 1.Power transformer 2.Distribution transformer
  6. Three phase Transformer
  7. Transformer classified as per core
  8. COOLING METHODS OF A TRANSFORMER For dry type transformers •Air Natural Or Self Air Cooled Transformer • Air Blast For oil immersed tranformers •Oil Natural Air Natural (ONAN) •Oil Natural Air Forced (ONAF) •Oil Forced Air Forced (OFAF) •Oil Forced Water Forced (OFWF)
  9. Air Natural Or Self Air Cooled Transformer This method of transformer cooling is generally used in small transformers (upto 3 MVA). In this method the transformer is allowed to cool by natural air flow surrounding it. Air Blast For transformers rated more than 3 MVA, cooling by natural air method is inadequate. In this method, air is forced on the core and windings with the help of fans or blowers. The air supply must be filtered to prevent the accumulation of dust particles in ventilation ducts. This method can be used for transformers upto 15 MVA.
  10. This transformer cooling method is generally used for large transformers upto about 60 MVA. This method can be used for transformers upto about 30 MVA. ONAF ONAN
  11. Oil Forced Air Forced (OFAF) This type of cooling is provided for higher rating transformers at substations or power stations.
  12. Oil Forced Water Forced (OFWF) This method is similar to OFAF method, but here forced water flow is used to dissipate hear from the heat exchangers.
  13. Power Transformer Power transformers are used in transmission network of higher voltages for step-up and step down application (400 kV, 200 kV, 110 kV, 66 kV, 33kV) and are generally rated above 200MVA. Power transformer generally operated at full load. Hence it is designed such that copper losses are minimal.
  14. Distribution Transformer • It is used for end user connectivity. (11kV, 6.6 kV, 3.3 kV, 440V, 230V) and are generally rated less than 200 MVA. • Distribution transformer is always online and operated at loads less than full load for most of time. Hence, it is designed such that core losses are minimal.
  15. A wide variety of transformer designs are used for different applications.  Auto-transformer  Poly-phase transormer  Leakage transformer  Resonant transformer  Instrument transformers
  16. AUTO-TRANSFORMERS Autotransformer is a one winding transformer in which a part of the winding is common to both HV & LV sides.
  17. POLY-PHASE TRANSFORMER • Three separate single phase transformers are suitably connected for 3 phase operation. • A single three phase transformer in which the cores and windings for all the three phases are combined in a single structure.
  18. INSTRUMENT TRANSFORMERS A current transformer is a measurement device designed to provide a current in its secondary coil proportional to the current flowing in its primary. A voltage transformer are designed to have an accurately known transformation ratio in both magnitude and phase, over a range of measuring circuit impedances..
  19. Losses in transformer (I) Core Losses Or Iron Losses a) Hysteresis loss b) Eddy current loss (ii) Copper loss Copper loss is due to ohmic resistance of the transformer windings. Copper loss for the primary winding is I1 2R1 and for secondary winding is I2 2R2. Where, I1 and I2 are current in primary and secondary winding respectively, R1 and R2 are the resistances of primary and secondary winding respectively.
  20. Hysteresis Loss The magnetic core of transformer is made of ′Cold Rolled Grain Oriented Silicon Steel′. Steel is very good ferromagnetic material. That Ferromagnetic substances have numbers of domains in their structure. The domains are situated randomly in the structure of substance. Whenever external magnetic field is applied , these randomly directed domains get arranged themselves in parallel to the axis of applied mmf. After removing this external mmf, maximum numbers of domains again come to random positions, but some of them still remain in their changed position. Because of these unchanged domains, the substance becomes slightly magnetized . To neutralize this magnetism, there will be a consumption of electrical energy which is known as Hysteresis loss of transformer.
  21. Eddy current loss In transformer, we supply alternating current in the primary, this alternating current produces alternating magnetizing flux in the core and as this flux links with secondary winding, there will be induced voltage in secondary, resulting current to flow through the load connected with it. Some of the alternating fluxes of transformer; may also link with other conducting parts like steel core or iron body of transformer etc. As alternating flux links with these parts of transformer, there would be a locally induced emf. Due to these emfs, there would be currents which will circulate locally at that parts of the transformer. These circulating current will not contribute in output of the transformer and dissipated as heat. This type of energy loss is called eddy current loss of transformer.
  22. Transformer Protection 1.Buchholz Relay 2.Earth Fault Relay 3.Differential Relay 4.Overcurrent Relay General Faults in Transformer 1.Open circuit fault 2.Overheating or Overloading fault 3.Winding short circuiting fault 4.Faults due to lightning Protecting Relay
  23. Buchholz Relay Protection Buchholz relay for transformer protection is only applicable for oil immersed transformer- used mostly for transformers with ratings above 750KVA, it provides protection from all kinds of faults. The concept of this relay is to utilize Hydrogen producing from fault heat. That is if a fault occurs either slow or fast there will be immense heat and this heat will create hydrogen from transformer oil.
  24. Earth Fault Relay “Earth fault” means one of the core is being connected or leaked to the earthing or grounding. This happens when insulation is damaged and coil is in touch with transformer body and body of transformer is certainly connected to the ground for safety.
  25. Differential protection Differential protection is provided in the electrical power transformer rated more than 5MVA.
  26. Bushing Bushing is an important part of power transformer. It is used to insulate the incoming or outgoing conductor into or out of a grounded barrier, in power transformer case is the transformer main tank. The bushings connect the windings of the transformer to the supply line and insulate the feed through conductor from the transformer main tank.
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