class: center, middle # EE-361 # MT1-RECITATION ## Ozan Keysan [ozan.keysan.me](http://ozan.keysan.me) Office: C-113
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Tel: 210 7586 --- # Group Recitation -- - # Make groups of 3 people -- - # Go to www.socrative.com -- - # Student login -> EE361 -- - # Wait for the questions --- ## Don't try to write it up everything! ## You can [download the solutions](../files/ee361_MT1_recitation_2016.pdf) --- #Q1- ## A 10 MVA 13.8/79.7 kV step-up transformer has a total leakage reactance of \\(X=1.9 \Omega\\) referred to primary side (LV) side. Neglect all transformer losses and the parallel branch. If the transformer is supplying rated MVA at rated voltage at 0.8 pf lagging: -- ## a) Find the referred secondary rated current to primary side (I2') -- ## b) Find the actual value of the load current --- #Q1- ### A 10 MVA 13.8/79.7 kV step-up transformer has a total leakage reactance of \\(X=1.9 \Omega\\) referred to primary side (LV) side. Neglect all transformer losses and the parallel branch. If the transformer is supplying rated MVA at rated voltage at 0.8 pf lagging: -- ## c) Find the primary voltage magnitude. -- ## d) Voltage regulation under these operating conditions. -- ## b) Now find the regulation for a leading 0.8 pf. at rated MVA. --- #Q2- ### The magnetic circuit shown in the figure is excited by a PM, whose characteristics is given in the Figure below: --
-- ### The maximum energy product operation point is \\(B_m=0.23 T\\), \\(H_m=-144 kA/m\\). Find the length of the magnet to produce max. energy product. --- #Q2- ### The maximum energy product operation point is \\(B_m=0.23 T\\), \\(H_m=-144 kA/m\\). Find the length of the magnet to produce max. energy product. ### \\(A_g=A_m=A_s= 10 cm^2\\) ### \\(l_s= 100 cm\\) ### \\(l_g= 1 cm\\) ### \\(\mu_r=500\\) --- #Q3- ## A 16.67 kVA, 7200/120 V, 60 Hz transformer has the following equivalent circuit parameters. ### \\(R_c = 311 k\Omega\\) \\(\quad X_m = 54.8 k\Omega\\) ### \\(r_1 = 18.7 \Omega\\) \\(\quad X_1 = 77.8 \Omega\\) ### \\(r_2 = 0.00519 \Omega\\) \\(\quad X_2 = 0.0216\Omega\\) --- #Q3- ## The adjusted voltage applied to the primary terminals is adjusted so that the secondary side voltage is 120 V, then the load power is 16.67 kVA at the unity pf. --- ## Find the primary current and the required primary terminal voltage by use of: -- ## a) The simplified equivalent circuit with only the containing the primary and secondary leakage reactances. -- ## b) The simplified equivalent circuit with the exciting branch moved to the primary terminals -- ## c) Complete equivalent circuit. --- ## Find copper and core losses, and the transformer efficiency under these conditions by using the complete equivalent circuit. --- ## Other Exercises #Q4- ## A 10 kVA, 220/110V, 50 Hz single phase transformer delivers rated power (operates at full-load) to its load at rated secondary voltage at 0.8 pf lagging. Calculate: -- ### a) Primary voltage magnitude using given approximate equivalent circuit -- ### b) Phase difference between primary and secondary voltage -- ### c) Efficiency --- # Q4- -- ## For the same transformer, assume the number of turns in the primary side is 44. What should be the dimensions of a square core such that, the flux density in the transformer is 1.5 T at no-load? --- # Q5- -- ## Assume you have a 50 kVA, 2400/240 V transformer. -- ## Short-circuit test is applied with the instruments on the high voltage side, and the following measurements are taken: -- ## V1 = 48 V, Isc=20.8 A, Psc = 617 W -- ## a) Calculate the primary and secondary side resistances and reactances using the primary side referred circuit. --- # Q5 -- ## b) Now the open-circuit test is applied from the high-voltage side and following measurements are taken: -- ## V1=2400V, Ioc=0.541 A, Poc=186 W -- ## Calculate the core loss resistance and the magnetizing reactance. --> --- # Next Question? --- ## You can download this presentation from: [keysan.me/ee361](http://keysan.me/ee361)