# home work

## Quiz by Ali

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38 questions
• Q1
Three phase voltage in Bahrain is
240V
415 V
NONE OF THEM
220 V
30s
• Q2
Single phase voltage in Bahrain is
240V
NONE OF THEM
415 A
415 V
30s
• Q3
………….. , ………….. two types of rotor in S.G
Non Salient pole rotor cylindrical Rotor
Both (a) and (b)
Salient pole rotor
None of them
30s
• Q4
The meaning of balanced load is
VPH1 = VPH2 = VPH 3
VL= VPH
None of them
Rph1 = Rph2 = Rph3
30s
• Q5
The main advantages of using AC over DC for power generation
possibility to use transformer
possibility to use generator
possibility to use motor
possibility to use diode
30s
• Q6
The current that passes through the neutral in balance load is:
5V
0A
3A
0 v
30s
• Q7
In Delta connections, the line voltage is 415Vand the phase current is 15A. What is the line current ?
IL= 1.73*15 = 25.9 A
None of them
VPH = 415 V
I ph= 15 A
30s
• Q8
For the three phase balanced star connected system shown in VL= 380 V, Rph = 20 Ω What is the Phase voltage
219.6 V
380V
19A
19V
30s
• Q9
For the three phase balanced star connected system shown in Vph= 220 V, Rph = 20 Ω What is the Phase current
19A
IPH = Vph /Rph=220/20=11A
19V
219.6 V
30s
• Q10
The Reactive power is……………..
The real power dissipated in AC system((useful power )
The voltage between 2 lines
30s
• Q11
The meaning of connection of three-phase transformer ( Dy1)
Primary connected delta, secondary connected star and angle=-30◦
Primary connected delta, secondary connected star and angle=180◦
Primary connected delta ,secondary connected delta and angle=0
Primary connected delta ,secondary connected star and angle=+30◦
30s
• Q12
the Formula of Active power in three phase system
√3 VL IL sin⁡θ
3 VL IL cos⁡θ
both a & b
√3 VL IL cos⁡θ
30s
• Q13
What types of the figures show 3 phase transformer, Name it?
Step up TRANSFORMER
three single- phase transformers
Step down TRANSFORMER
SINGLE 3-PHASE TRANSFORMER
30s
• Q14
Which type of transformer shown in the figure ?
three single- phase transformers
Step up TRANSFORMER
SINGLE 3-PHASE TRANSFORMER
Step down TRANSFORMER
30s
• Q15
the main advantage of three single phase transformer is
MORE EFFICIENT
every unit in the bank could be replaced individually
SMALLER
CHEAPER
30s

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