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Transcript
```University of Hail
Electrical Engineering Department
Second Semester (092) / 2009 - 2010
Major # 1
Instructor: Dr. Ramzi A. Abdul - Halem
Course : Electric Energy Engineering (EE 206)
Date
: Saturday, April, 3rd, 2010
Period : 60 minutes
Student Name:
Student ID # :
Question 1
/ 25
Question 2
/ 25
Question 3
/ 25
Question 3
/ 25
Total Mark
/ 100
Good Luck
EE206 Electric Energy Engineering
Major 1
Q1: (25) Points
1. An electrical power supply has a voltage source V = 100 / 0 o V delivers power to
two parallel loads of impedances z
2
= 3 – j4 Ω, and z
3
= 5 + j5 Ω , through a
feeder of impedance z1 = 8 – j6 Ω. Determine (a) the current drown by each
impedance and (b) the complex power taken by each impedance.
2
EE206 Electric Energy Engineering
Major 1
Q2: (25) Points
A toroid has a circular cross section as shown in Fig. 1. It is made from cast steel with a
relative permeability of 2500. Its outer diameter is 24 cm, and its inner diameter is 16 cm.
the magnetic flux density in the core is 1.25 tesla measured at the mean diameter of the
toroid.
(a) Find the current that must be supplied to the coil, which consists of 250 turns.
(b) Determine the magnetic flux in the core
Figure 1
N = 250 turns
3
EE206 Electric Energy Engineering
Q3: (25) Points
Major 1
1. A 25-KVA, 2300/230-V, single-phase transformer has a high-voltage winding with a
resistance of 1.5 Ω and a leakage reactance of 2.4 Ω. The low-voltage winding has a
resistance of 0.015 Ω and a leakage reactance of 0.024Ω. the core loss is 175 W. Find the
following:
(a) Equivalent impedances referred to the high-voltage winding.
(b) Voltage regulation for full load at 230 V and 0.866 power factor lagging
(c) The efficiency of the transformed under the condition of part (b)
4
EE206 Electric Energy Engineering
Q4: (25) Points
Major 1
2. Three single-phase, 20/2.4-KV, ideal transformers are connected to form a three-phase, 10MVA, 34.5/2.4-KV transformer bank. The transformer bank supplies a load of 6 MW at 2.4 KV
and 0.85 power factor lagging. (Draw the schematic diagram of the required transformer)
a. Determine the line and phase currents at the primary and secondary sides of the
transformer.
b. Determine the line-to-line and line-to-neutral voltage at the primary and secondary
sides of the transformer.
5
```