Chemistry Sec. B & C

TUTORIAL NO.1

Qu.1) In a 50 KVA transformer, the Iron loss is 500W & full-load copper loss is

          800W. Find the efficiency at full-load and half full-load at 0.8 P.F. lagging.

Qu.2) A 600 KVA, 1- phase transformer has an efficiency of 92% both at full-

          load and  half-full load at unity P.F. determine its efficiency at 60% of full-

          load at 0.8 P.F. lag.

Qu.3) A 10 KVA single-phase transformer for 2000/400 V at no load, has  

          R1 = 5.5Ω, X1 = 12 Ω, R2 = 0.2 Ω, X2 = 0.45 Ω, determine. Value of

          secondary voltage at full-load, 0.8 P.F. lagging when primary applied

          voltage is 2000 volt.

TUTORIAL NO.2

Qu.1) A 40 KVA transformer has a core loss 400 W at full-load, copper loss is

          800 W. If the power factor of load is 0.9 lagging. Calculate

(a)  full load efficiency    

(b)  percentage of full load at which maximum efficiency occurs.

Qu.2) In a 50 KVA, 11 KV/400 V transformers the Iron and Cu losses are 500 W   

          & 600 W. Calculate efficiency on unity factor at full load. Find load for

          maximum efficiency & Iron and copper losses corresponding to this load.

Qu.3) A T/F rated 200V/50 V, 10 KVA has core loss of 100 watts. What is the

          max. Efficiency of T/F at 0.8 P.F. Lagging. Assume full load Cu loss as

          200 W. At what load this max. Efficiency is obtained?