Documents/Reports

• Suspension clamps are used at all suspension points to support the earth wire. The clamps shall conform to IS:2486 and shall give adequate are of support to the earth wire. The groove of the clamp should be smooth finished in uniform circular or oval shape so that there shall not be any displacement in configuration of the earth wire strands nor shall these be unduly stressed in final assembly.
• The following types of suspension clamp are in use :-
  • Conventional type :-
    This type of suspension clamp shall hang from U-bolt which is fixed vertically downwards in the ground wire peak of suspension tower. The U-bolt is part of the tower and is fixed in the direction of the run of line.
    
    

    

  • Seated Type :-
    This type of suspension clamp is fixed with the help of 4 nos 16 diax40mm bolts on the base provided at the ground wire peak of suspension tower.
    
    

    

• Technical Particulars of Suspension Clamps
  1. Dimensional details :

Table 17-I

• The compression type tension clamp is used at all the tension towers to hold 7/3.67mm and 7/3.25 mm GS earth wire. The assembly is connected to 22/20.5mm dia hole in 8mm thick horizontal strain plates of the tower body by means of D-Shackle. The jumper terminal attachment plate is welded with dead and at an angle of 300 C from the vertical plane. The jumper terminal is fixed with attachment plate by means of bolts & nuts. The compression tube and jumper tube give adequate area of support without any slip to the earth wire under normal working tension and vibration conditions.
  
  

  

• Technical Particulars

Table 17-II

• These joints are used for jointing two length of 7/3.67mm and 7/3.25mm GS earth wire. These are made of mild steel rods such that it does not crack or fail during compression. It shall be easily compressible with 100 ton hydraulic compressor.
  
  

  

• Technical Particulars :
  

  1. Table 17-III

     Suitable for earth wire size	Dimensions (mm)
     	Before compression			After compression
     	Length	Internal Dia	External Dia	Length	Corner to Corner	Face to Face
     7/3.67mm	230	11.5	21	250	20	17.5
     7/3.25mm	203	10.3	18	220	17.4	15.1

  2. Indian Standard to which Mid Span joints shall conform IS:2121
  3. Material of construction-mild steel (hot dip galvanized)
  4. The ultimate breaking strength and slip strength of the joint after compression Not less than 90% of UTS of earthwire.
• UTS of earth wire
• 7/3.67mm -7030Kg
• 7/3.25mm -5510 Kg

Vibration dampers suitable for 7/3.67mm earth wire are provided at all tension and suspension points of each earth wire in each span (at least one at each end of each earth wire span up to span of 450 meter) to damp out the vibration up to a residual limit of 150 micro strains. The dampers shall effectively damp out the vibration of earth wire for full frequency range experienced in the earth wire for spans from 200 to 450 meters and wind velocity up to 30 Kms per hour.

• Technical Particulars :

Table 17-IV

Distances of damper are to be measured from centre line of suspension clamp or mouth of dead end assembly up to centre of damper clamp.