Visvesvaraya Technological University (VTU) 2006 B.E Electrical and Electronics Engineering 6th SEM ELECTRICAL DRAWING AND CAD - exam paper

USN							1 1 1 j ;
NEW SCHEME

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.

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 / 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)

PART-B

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)

Attachment: visvesvaraya-technological-university--vtu--2006-b-e-electrical-and-electronics-engineering-41878-1.jpg visvesvaraya-technological-university--vtu--2006-b-e-electrical-and-electronics-engineering-41878-2.jpg

Earning:   Approval pending.