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INSTRUCTIONS
(1) Assume appropriate data and state your reasons
(2) Marks are given to the right of every question
(3) Draw neat diagrams wherever necessary

Solve any one question from Q.1(a) & Q.1(b)
1(a) Design & draw the developed double layer lap winding of DC armature with 24 conductors and 4 poles. Also show the direction current in the coils and brush position. Draw the sequenc diagram.
30 M
1(b) Draw the developed winding diagram for an AC machine with following details:
a) Speed = 3000rpm
b) no of slots = 24
c) Frequency = 50 Hz
d) Phase = 3 short pitch by 5/6 double layer lap and star connected.
30 M

2 Draw a single line diagram of a typical substation:
Transformers: -2, 5MV, 66/11KV, delta/delta, 3phase, 50HZ.
Auxiliary tranformer: -1, 11KV/400V, delta/star, 3phase, 50 HZ.
Incoming lines: -2, 66KV Outgoing lines: -1, 66KV outgoing lines: -5, 11KV
66KV and 11 KV buses are double bus with a bus coupler
Coupling condenser, wave trap, earthing switches, are to positioned at the incoming lines. Indicate the positions of CT, PT, isolating switches and lighting arrestors.
20 M

3 The following are the details of three phase core type Transformer. Draw to a suitable scale.
a. Elevation of the 3 transformer assembly showing one limb in section
b. Plan of Transformer assembly showing one limb in section
Core: Step construction, Core diameter = 220mm, Height of the core = 480mm, Height of the yoke = 250mm, Center to Center distance between the limbs = 350mm
LV winding:
Inside diameter = 231 mm
Winding is two layer total radial former = 13.3 mm
Radial thickness of one layer = 7.4mm
Thickness of LV former = 3mm
Number of turns/layer = 13
Total height of LV Winding = 427mm
HV winding:
Outside diameter = 340mm
Total number of coils = 12
a. Two coils of end gun metal ring each of 14mm thickness
b. Ten coils of 56 turns each,
Total height of winding = 427mm,
Average and clearance 33mm from top and 200mm from bottom of the yoke.
50 M

4 Draw to a suitable scale end and longitudinal elevation (top half in section) of a 100 KW, 500V, 1250 R.P,P 6 pole DC shunt generator. The armature is supported over the spider and the shaft is supported by means of pedestal bearing for the dimensions given below.
Armature:
Outside diameter = 75 cm.
Length = 27.8 cm
Number of slots = 86
Size of slot = 1.11 cm × 5.24 cm
Depth of iron behind the slot = 9.26 cm
Ventilating ducts = 3, each 1 cm width Air gap length below main pole = 0.5 cm.
Main Pole (laminated) :
Total height = 24 cm with shoe
Width = 17.75 cm
Length = 25.7 cm
Interpole (solid):
Breadth = 4.63 cm Length = 20 cm
Air gap length below interpole = 0.8 cm
Yoke:
Thickness of yoke = 7.5 cm
Length of yoke = 40 cm
Commutator :
Number of commutator segments = 344
Diameter = 56 cm
Segment pitch = 0.51
Length = 12.35 cm
Number of brushes per spindle = 3
Shaft:
Shaft diameter below armature = 9 cm
shaft length between bearing centers = 120 cm.
50 M

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