1) Data of a 500KVA, 3300/400 V, 50 Hz ,single phase transformer is given below. S.C test: 1250 W, 100 V –secondary short circuited with full load current in it O.C test : 1000 W –with normal primary voltage. Compute the full load regulation and efficiency at a power factor of 0.8(lag).
2)(a) Deduce an equivalent circuit of single phase two winding transformer.
(b) Maximum efficiency of single phase 250kVA,2000/250 V transformer occurs at 80% of full load and is equal to 97.5% at 0.8 pf. Find out the efficiency and regulation on full load at 0.8pf lagging if the impedance of the transformer is 9 percent
3) Describe about tap changing of transformers in detail.
4) prepare down the basic feature of electromagnetic energy conversion devices.
5) Describe why does energy storage in the magnetic material occurs mainly in air gap?
6) What do you mean by multiply excited magnetic field system?
7) prepare down the relation between energy and co-energy for linear system.
8) prepare down the suitable exs for each of single and multiple excited system.
9) prepare down the applications of singly and doubly fedmagnetic systems.
10) Describe why the field in rotating machines must be quasi-static in nature?
11) prepare down the causes for irrecoverable energy loss when flux in magnetic circuit undergoes a cycle.
12) describe why relationship between current and coil flux linkages of electromechanical energy conversion devices are linear
13) In which direction does force act with respect to magnetic field?