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A typical V-Cross Arm is as follows……

V Cross Arm

This is the actual design to be adopted for stringing of 11KV HT lines.
This pattern avoids bird faults, touching of Phase to Phase lines, foreign material falling on lines and twisting of lines.
The V–Cross Arm Pattern is not being used in Urban Areas due to clearance problem from the buildings. Instead Horizontal Side Arm is used.

Horizontal Side Arm used in Urban Areas is as follows….
Horizantal Side Cross Arm used in Urban Area

Modified V-Cross Arm (triangular formation) by raising Middle Phase…..
V-Cross Arm with Middle Raising

Merits of Providing Middle Phase Raising
> Phase to phase clearance increased from 18″ to 42”
Foreign material falling on lines will be reduced due to triangular formation
.  of line as these materials will fall to ground instead of resting on lines
.  Touching of phase to phase during gale and due to kite flying will be
.  predominantly reduced
> Touching of phase to phase due to swing caused by various faults and
.   there by twisting of lines and consequent line snapping can be reduced
> With this pattern even bird faults can be avoided as birds intends to sit on
.   the top of the middle phase
> These extension phases can be used to get adequate clearances between
.   existing LT and HT lines
>  It takes hardly 20 minutes to provide each cleat ( MPX)

In 2008, a Pilot Project was taken up at about 600 locations in CBD Azamabad City-2 area of Hyderabad Central Circle where horizontal side arms are replaced with modified to V-cross arms pattern by providing middle phase extension.

Specifications of Middle Phase Extension (MPX) are as follows….
(Pic is shown below)
*  M S angle size of 50 x 50 x 6 mm – 2.4 to 2.6 feet in length
*  M S channel size of 100 x 50 x 6 mm— 4 inches width with suitable holes
.   for 11KV GI pin and full welding to angle

Middle Phase Raising

– By Er. S S Subba Reddy
Asst. Divisional Engineer (Elec)/M & P/Siddipet

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