Visvesvaraya Technological University (VTU) 2006 B.E Electrical and Electronics Engineering 6th SEM ELECTRICAL DRAWING AND CAD - Question 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: 100
Note: 1. Answer any FOUR questions from. PART-A and any ONE question from PART-B.
2. Assume any missing data.
PART-A
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 / 1 I 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 PT's wherever necessary, (20 Marks)
\ 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)
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)
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,.he 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 cooling ducts = 2; Diameter of commutator = 23 cm; Axial length of commutator =11.5 cm; Number of poles = 4; Pole height = ]6 cm; Pole width -
12 cm; Pole arc = 0.65; Pole pitch = 90; Number of inter poles = 4; Inter pole dimensions 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 siator has ventilating duct ofl.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 preparatory 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 ar-j 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 tums / 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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