Civil Engineer , Site Engineer JOB

Urgent Vacancy for transmission line projects

location – Near NCR AND DELHI

EXPERIENCE -0-2

SALARY – 7 LAKH

BUT BEFORE APPLYING PLEASE READ BELOW FOR INTERVIEW QUESTION BECAUSE INTERVIEW IS VERY TOUGH

IF YOU READ OUT ALL THESE QUESTION THEN YOU WILL BE SELECTED

WHAT IS PRELIMINARY WORKS ?

SELECTION OF ROUTE
1.0 CRITERIA FOR ROUTE SELECTION:
1.1 The route of a transmission line is decided from the following main considerations.
a) Shortest length, hence least capital cost.
b) Ease during construction and ease in maintenance of the line (route near roads for
easy approach & accessibility).
c) Requirement of future loads (sub stations) near the proposed route so that the line can
be easily connected.
d) Required separation distance from parallel communication lines (P&T, Railways,
etc.) for meeting the conditions of induced voltage for obtaining PTCC approval.
e) Avoiding of forest areas as well as wild life sanctuaries.
f) Cost of securing and clearing right of way (ROW).
g) Maintaining statutory distances from Airports / Helipads.

WHAT IS (PTCC):

2.1 The line route shall be so selected that the voltage induced in parallel running telegraph /
telephone / communication / signaling lines / circuits of the P&T Department/ Railways does
not exceed the prescribed permissible values under fault conditions. The PTCC approval
should be obtained before energizing the line.

WHAT ARE THE APPROVAL OF THE AVIATION AUTHORITIES:

3.1 The line route shall be at a sufficient distance from the aerodromes / airports so that clearance
from the aerodrome / airport authorities is not required or, otherwise, can be obtained easily.

4.0 CROSSING OF RAILWAY TRACKS:
4.1 The crossing of Railway tracks shall normally be outside the railway station limits.
5.0 CROSSING OF RIVERS / NALAS / ROADS:
5.1 Crossing of rivers / nalas is preferably done at points where the bed is of the smallest width
and the banks on both sides of the rivers / nalas are high. The crossing is done at points of the
river path where it is unlikely to cut the banks when it is flowing.
5.2 The route is selected such that multiple crossings of the same road are avoided.
5.3 Crossing of roads at very small angles is to be avoided.
6.0 CROSSING OF POWER LINES:
6.1 When crossing existing higher voltage power lines, the new line shall normally be below such
existing lines except in extremely limiting circumstances.
6.2 When crossing existing lower voltage power lines, the new line shall normally be above such
existing lines except in circumstances where it is not possible.
6.3 When crossing existing power lines of the same voltage, the new line may be above or below
such existing lines as per site conditions.

7.0 APPROVAL OF FOREST DEPARTMENT:
7.1 Forest area is to be avoided as far as possible.
7.2 If forest area cannot be avoided, or if the line route is uneconomical in case forest area is
avoided, then the approval of the Forest Department is required.

WHAT IS RECONNAISSANCE SURVEY?

Reconnaissance survey of the transmission line route is to be carried out for deciding upon the
most economical line route and the most economical location of towers in view of the high
cost per location.

MEASURE OF EARTH REGISTIVITY?

Measurements of earth resistivity shall be made at every 2 to 3 km along the tentative route of
the transmission line. In case soil characteristics change within 2 to 3 km, the earth resistivity
shall also be measured at intermediate locations wherever such characteristics change. The
megger reading and soil characteristics shall also be indicated in the earth resistivity results.
2.2 Earth resistivity along the route alignment shall be measured in dry weather by the four
electrode method keeping inter – electrode spacing of 50 metres.

WHAT IS PRELIMINARY SURVEY?
1.0 FIXING OF ROUTE ALIGNMENT:
1.1 The alignment of the line route is carried out by survey using a theodolite.
1.2 The following positions are fixed during this survey.
a) Fixing of angle tower positions.
b) Finalizing of crossing points of major EHV lines (66 kV and above) & details of the
lines.
c) Finalizing of crossing points of Railway Tracks & details of such points.
d) Finalizing of crossing points of major rivers & details of such points.

TOWER TYPE

For the purpose of guidance, the angles of deviation of the different types of towers are as
below:
Tower type Used as Angle of deviation
‘A’ Suspension tower upto 2 degrees
‘B’ Small angle tower upto 15 degrees
‘C’ Medium angle tower upto 30 degrees
‘D’ Large angle & dead end tower upto 60 degrees & dead end

The basic spans,

which are the design spans for towers, as adopted for the various voltage
levels are as below:
Voltage Level Basic Span
400 kV 400 metres
220 kV 350 metres
132 kV 335 metres

MOST IMPORTANT-

CALCULATION OF EXCAVATION AND CONCRETE
VOLUMES OF TOWER FOUNDATION.
(Based on typical drawing of the tower foundation shown above in this Appendix)
CALCULATION OF EXCAVATION VOLUME
Excavation Volume = 4 × {Base of pad + (2 × 0.150 m)}2 × depth of the pit
= 4 × (1.225 + 0.300)2 × 3.400
= 4 × 1.5252 × 3.400
Total Excavation Volume = 31.6285 cu.m.
CALCULATION OF CONCRETE VOLUME
Concrete Volume = Concrete volume of Pad + concrete volume of Frustum + concrete
volume of Chimney + concrete volume of Coping.
Concrete Volume of Pad = 4 × (Base of pad)2 × height of pad
= 4 × 1.2252 × 0.050
= 0.3001 cu. m.
Concrete Volume of Frustum = 4 × height of frustum × [(Base of frustum)2 + (Top
3
of frustum)2 + √{(Base of frustum)2 × (Top of frustum)2}]
= 4 × 0.475 × {1.2252 + 0.3002 +√(1.2252 × 0.3002)}
3
= 4 × 0.1583 × 1.9581
= 1.2398 cu.m.
Concrete Volume of Chimney = 4 × (width of chimney)2 × height of chimney
= 4 × 0.3002 × 3.100
= 1.116 cu.m.
Concrete volume of Coping = 4 × 0.075 × {0.3002 + 0.1002 +√(0.3002 × 0.1002)}
(as for frustum) 3
= 4 × 0.025 × 0.130
= 0.013 cu.m.
(The top of the coping has been taken as 100 mm based on the size of the stub angle)
Total Concrete Volume = 0.3001 + 1.2398 + 1.1160 + 0.0130
= 2.6689 cu.m.