Figure-01: Procedure of Vector Group Test of Transformer
Let's have a YNd11 transformer,
(a) Connect neutral point of star connected winding with earth.
(b) Join 1U of HV and 2W of LV together.
(c) Apply 415 V, three phase supply to HV terminals.
(d) Measure voltages between terminals 2U-1N, 2V-1N, 2W-IN, that means voltages between each LV terminal and HV neutral.
(e) Also measure voltages between terminals 2V-1V, 2W-1W and 2V-1W. For YNd11 transformer, we will find,
2U-IN >2V-IN > 2W-IN
2V-1W>2V-1V or 2W-1W.
The vector group test of transformer for other group can also be done in similar way.
Related Question
View All
Maximum Power Transfer Theorem :
In electrical engineering, the maximum power transfer theorem states that, to obtain maximum external power from a power source with internal resistance, the resistance of the load must equal the resistance of the source as viewed from its output terminals.
Let Impedance of,
Xc near the terminal X is Z1=-j10
10 ohm resistance, Z2=10
3 ohm resistance, Z3=3
XL, Z4 =j14
Xc near to source, Z5=-j10
Now,
Zth=[Z5 || (Z3 +Z4) ] + Z2 +Z1
= [ -j10 || (3+j4)] + 100- j10
= 112 - j36
For t<0, the switch is closed.
Capacitor acts as open to DC.
Voltage across the capacitor,
v(0-)= {(12||4)×V}÷{(12||4)+6} = 8VFor t=0, the switch is opened,Voltage across the Capacitor cannot change instantaneously,So, v(0-)= v(0) = 8VAt t>0, The capacitor is discharging.Rth = (12||4) = 3 ohmC= 1/6 FTime constant, Π = Rth×C = 0.5 So, v(t) = v(0)e-t/Π = 8e-t/0.5 =8e-2t V (Ans.)
The initial energy stored in the Capacitor,
W=(1/2)CVo2
= 0.5×0.167×82
= 5.333J (Ans)
১ ক্লিকে প্রশ্ন, শীট, সাজেশন ও
অনলাইন পরীক্ষা তৈরির সফটওয়্যার!
শুধু প্রশ্ন সিলেক্ট করুন — প্রশ্নপত্র অটোমেটিক তৈরি!
Related Question
Complete Exam
Preparation
Learn, practice, analyse and improve
