1
Example
1:- A (40 KVA, 50 Hz) single phase transformer has (400) turns on the
primary windings and (100) turns on the secondary windings, the supply voltage is
(2000 V) on the primary. Determine the followings:-
1- The secondary voltage when the transformer is operating as open circuit.
2- The full load current of the both sides (primary and secondary).
3- The maximum value of the flux (ɸ
max
).
4-
Example 2
:-
A single phase transformer has (1.1 Volt /turn) . when the primary
winding is supplied by (220 V, 50 Hz) the secondary winding voltage is (550 V).
Determine the followings:-
1- The number of the primary and secondary windings.
2- The cross section area of the iron core if the flux density is (B= 1.2 Tesla).
Example 3
:-
A (200 KVA) single phase transformer (V
1
=6600 V & V
2
= 400 V), the
number of the secondary windings is (N
2
= 80 turn). If the transformer is operating at
(50 Hz), then determine the followings:-
1- The number of the primary windings (N
1
).
2- The maximum value of the flux (ɸ
max
).
3- If the transformer is operating at (25 Hz), and the flux increased by (10%) of its
value then determine the followings:-
a- The new value of the primary voltage (V
1
).
b- The new value of the transformer power in (KVA), assuming the values of the
primary and secondary (I
1
& I
2
) remains constant.
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Example 4:
-
A single phase transformer (V
1
=300 V & V
2
= 3300 V), at the no load
the current is (I
o
= 0.6 A) and the power is (P
o
=60 W) when the supply voltage is
connected to the low voltage side and the high voltage side us open circuited , then
determine the followings:-
1- The power factor at no load (PF).
2- The tow components of the no load current.