Visvesvaraya Technological University (VTU) 2006 B.E Electrical and Electronics Engineering 6th SEM ELECTRICAL DRAWING AND CAD - exam paper
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Sixth Semester B.E. Degree Examination, July 2006 Electrical and Electronics Engineering Electrical Drawing and CAD
Time: 3 hrs.] [Max. Marks:ICO
Note: 1. Answer any FOUR questions from PART-A and any ONE question from PART-B.
2. Assume any missing data.
1 Draw the single line diagram of a 33 KV / 11 KV substation with following equipments:
a. One 33 KV incoming line connected to 33 KV bus bar.
b. Two 3 winding transformers of ratings 5 MVA and 3 MVA with 33-KV / 11 KV each terminating at bus bar - 1 and bus bar - 2 respectively.
c. Two 11 KV OBCs.
d. Three 33 KV SOS units.
e. Four 11 KV outgoing feeders from bus bar 1 and 2 respectively. Provide lightning arrestors, isolators, circuit breakers, CTs and PTs wherever necessary. (20 Marks)
2 Draw a neat developed winding diagram for a PC machine with following details: Number of slots = 13; number of poles = 4; number of commutator segments 13: winding type simple double layer wave. Show the position of poles and mark, the position of brushes. Also draw the sequence diagram. (20 Marks)
3 Draw the developed winding diagram for an AC motor with following data: Number of slots = 12; number of poles = 4; number of phases = 3; winding type double layer, full pitched lap with star connection. (20 Marks)
4 Draw the following views of a 3 phase, 250 KVA, 11 KV / 400 V transformer core type.
a) Front elevation full section and b) Plan full in section.
Dimensions of various parts are given below:
Core: Cross section of the core = 3 step core.
Diameter of circumcircle = 24 cm.
Distance between adjacent centers of yoke = 42.5 cm.
Yoke: Yoke height = 25 cm.
LT Winding: Outside diameter of LT coil = 28.3 cm; Inside diameter of LT coil
- 25 cm; Height of LT winding = 43.5 cm.
Number of turns per phase =12.
HT Winding: Outside diameter of HT Coil =41.5 cm; Inside diameter of HT coil = 34.3 cm; Height of HT Winding = 43.5 cm.
Number of turns per phase =572.
Total height of transformer =100 cm. (20 Marks)
5 Draw the half sectional end view of a DC generator with the following dimensions:
Diameter of*Jie shaft = 5 cm; Outside diameter of armature = 36 cm; Axial length of armature = 25 cm; Armature winding over hang on each side 7.5 cm; Number of radial codling ducts = 2; Diameter of commutator = 23 cm; Axial length of commutator =11.5 cm; Number of poles = 4; Pole height = 16 cm; Pole width = 12 cm; Pole arc - 0.65; Pole pitch = 90: Number of inter poles = 4; Inter pole uimensions = 4cm X 15cm; Thickness of Yoke = 3.5 cm; Depth of slot = 2.5 cm. Show few slots on the armature. (20 Marks)
6 Choosing a suitable scale; draw the half sectional end view and half sectional longitudinal view of a 10 Hp, 3 phase. 50 Hz, 4 pole squirrel cage induction motor having the following dimensions:
Stator: Internal diameter =. 18 cm; Outside diameter = 32 cm; Gross length of stator core = 13.5 cm: Number of slots 36; Slot width = 0.77 cm; slot depth =
3.4 cm; Air gap length = 0.1 cm; The stator has ventilating duct of 1.3 cm width. Rotor: Number of slots = 31; Rotor bars = 0.51cm X 1.52cm; End ring area =
1.69 sq.cm: Shaft diameter = 5.1 cm; Overall height of the motor = 47.5 cm.
(20 Marks)
7 a. Write an Auto CAD program to draw 5 rows of five 10 mm circles each. All
circles are shaped 20 mm from center to center. Use Array Command.
(10 Marks)
b. Write the Auto CAD program to draw a semicircle of radius 50 mm and complete the circle using mirror command. (10 Marks)
8 Draw proportionate preparatoiy sketch and explain step by step procedure to draw the front elevation full in section of a single phase 220 V/ 110V, 5 KVA transformer using Auto CAD. The detailed dimensions art* as follows:
Core: Cross section One step core
Diameter of circumcirde = 7.5 cm
Distance between core centers = 15 cm
Yoke: Yoke height = 8 cm LT Winding: Outside diameter of coil = 9 cm Inside diameter coil = 8 cm Height of the coil = 23 cm Number of turns / limb = 50 HT Winding: Outside diameter of the coil = 13.5 cm Inside diameter of the coil =11.1 cm Height of the coil = 23 cm Number of turns / limb =100
Total height of transformer = 40 cm. (20 Marks)
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Earning: Approval pending. |