Question

You work as an engineer in the control department of a transformer manufacturer. A transformer with
the following nameplate data is manufactured after long 6 months. For the final delivery, you need to
determine the electrical resistances and electrical reactances. Nameplate data: A single phase, 150MVA,
300/100kV transformer.
(a) What type of tests you would apply to the transformer to calculate such data?
(b) Short-circuit test results are: 40 kV, 600 kW losses. Which two data you can calculate from this
test, then calculate them.
(c) Open-circuit test results are: 24 A, 12kW power losses. Which two data you can calculate from
this test, then calculate them.

Answer 1

Name plate details : 150 mUA. 300/100 KUA. ca). To calculate the electrical senstance and reactances of the transformer we can peform the following test: 1) Short wrcuit Test's - The LV side of the transformer is shorted and supply to tv side is giren and allowed to arculate the freei load short circuit current. This test gives feel load copper losses. calculate the total from this test we can reustemce and tractemce referred to HU side. 2) Open circuit testi The tv side of the tramtomer is kept open and Lr supply is given to the transformer. This test ques total core losses, from this test we can calculate the magnetising component xm and working le component Re (Renstemce). scanner

↑ Isc Roi Xol ib) SC Tests Vsc = 40 KV Wsc = 600kW, loc u Isc = VA rating HV Volterge = 150X10 300x103 = 500A Zona eve you to 2 = 801 Ws - 600X10 LE 2:42 i se (500) Xo = √2017 (201) = 49,962 Toc (6) OCTest Vy10DKV Xm Voc=100kv Joc=24A Woc = 12kW . Woc 12X10 cos do Vocx IDC 100x 103 x 24 cosdo=0.005 Eics scanned with co - 89.71 Be Cam Scanner

Sindo i sin (89.91) = 0,9999 Roz Va To,cos do looxio² 24 X 00005 = 833.33 km Voc xon 100x10 24x0.9999 .. locsindo = 4170.84.22 bom se tent we calcule Rol = 2.un Xol = 79.965 From Oc Testi Ro = 833 33k. Xm = 4170 84 s. Scanned with CamScanner