Transformer

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Transformer

  1. 1. SINGLE PHASE TRANSFORMERS 1
  2. 2. 1. components: -- 2 adjacent coils -- coils not physically connected to each other 2
  3. 3. 2. operation: a) AC in primary coil produces ∆ B b) Secondary coil receives a ∆ in I & V 3 N SN SN SN SN SN S
  4. 4. N n A B C a b c IA Ia VAN VAB VCN VBN Vbn Van Vcn Vab 4 Wye / Wye connection
  5. 5. Load Supply Network Transformer Y-Y Transformer LoadSupply Network Xtr_s Van Vload_an VAN Vnet_AN Xnet IA Ia N n A a 5 Three-phase network supplies a load through a transformer. Xtr_s Van Vload_an VAN IA IaVnet_AN Xnet Equivalent circuit of the wye-wye Single-phase equivalent circuit for phase A of the three-phase wye-wye transformer system
  6. 6. Wye / Delta connection 6 A B C N VAN VAB VBN VBC VCN IA Iba Icb VCA a b c a b c Ia Ic Ib Vab Vbc Vca Iac
  7. 7. Ia Ib Ic Vab Vbc Vca VCN VBN VAN A B C a b c Icb Iba Iac Transformer AC AC AC IC IB IA VAN VBN VCN Supply Iab Ibc Ica Load VAB VBC VCA Iac Vca Vbc Vab N 7 Wye-delta connected transformer
  8. 8. Xtr_s Van Vs_an VAN IA Ia Vp_AN Xtr_p Rtr_p Rtr_s Xm Rc Tspe Y-∆ 8 Single-phase equivalent circuit of a wye-delta transformer.
  9. 9. Delta / Wye connection 9 A B C n a b c VBC IaIA Ib Ic VAB VCA Vca Vab Vbc Van Vbn Vcn IC IB ICA IAB IBC
  10. 10. Delta / Delta connection 10 A B C a b c VAB Ia Iba Iac IA IAB ICA Vab
  11. 11.  ratio of the # of turns in the secondary coil to the # of turns in the primary coil 11 P S N N TR =  numerical factor indicating relative change in PD across a transformer TR > 1 = V (step up) TR < 1 = V (step down)
  12. 12.  ∆ in V is directly proportional to the ratio of the # of turns in the secondary to the # of turns in the primary  Formula: 12 N N V V S P S P = NS secondary coil turns NP primary coil turns VS secondary voltage VP primary voltage direct relationship
  13. 13.  Current in a transformer will be inversely proportional to the TR of the transformer  formula: 13 N N I I S P P S = V V I I S P P S = IP primary coil current IS secondary coil current  I vs. V = inverse relationship
  14. 14.  Based on TURNS RATIO 14 2. step-down turns ratio < 1 VS < VP IS > IP 1. step-up turns ratio > 1 VS > VP IS < IP
  15. 15. 1. air core --inside area of coil is empty -- inefficient induction 15 2. open core -- ferromagnetic material inside coils -- ↑B = ↑induction
  16. 16. 3. closed core -- ferromagnetic ends connected -- ↑Β = ↑ induction 16 4. shell -- lazy square eight -- overlap of coils on same ferromagnetic core

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