HOTLINE TECHNIQUE



ADOPTATION OF HOT LINE TECHNIQUE FOR MAINTENANCE OF EHT LINES AND STATIONS

In the modern age, Power bas become a major essential commodity after air, food, clothing and shelter, which play a major role for development of country. Hence, maintenance of Transmission line plays an important role in achieving minimum interruption, which results in not only revenue earnings for the organization, but also for major industrial growth and development of the country at large. Thus ensuring Power system stability and stable power supply, which calls for preventive maintenance of transmission lines(EHT lines) and Sub-stations.



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HOT LINE TECHNIQUE:

The Technique adopted to maintain transmission lines, by working on it when it is live is known as Hot Line Technique. This technique is also used to maintain the ODS of Sub-stations. The advantages of working in Hot Line technique over the convectional method.

  • It minimizes the interruptions.
  • No loss of revenue.
  • Maintenance can be carried out in its actual load conditions.
  • Maintaining the system stability.

METHODS OF HOT LINE WORKING::


  • 1.Hot Stick Method
  • 2.Bare hand technique
  • 3.Combination Method

HOT STICK METHOD: In this method the line men will be at ground potential and works with epoxy glass Hot Sticks and always safe clearance is maintained between mechanic and live potential. The Hot sticks used in this technique generally 12feet long and is made up of epoxy glass fibre having a insulation strength of 100 KV per foot and these are moisture resistant. The other hardware used along with Hot sticks is made up of high strength light weight alluminium alloy.
BARE HAND TECHNIQUE: This technique is based on the principle of Faradays cage theory. According to the theory no potential difference exists within a metal cage that has been charged to the same potential of conductor with respect to ground. There are no electrical charges and electric field inside with respect to ground. With no potential difference there will not be any flow of current.
COMBINATION METHOD: In this method both Hot stick and bare hand method are clubbed together for carrying out the Hot Line Works to overcome the constraints in the tower top arrangement.


WORKS WHICH CAN BE TAKEN UP USING HOT LINE TECHNIQUES:




  • Testing of insulators in Tangent/Anchor Tower. This is the only method with which the insulators in service can be tested.
  • Replacement of faulty string/disc insulators.
  • Tightening of P.G clamps, Fixing/Tightening of Vibration dampers.
  • Thermovision Scanning of joints for high temperature and tightening the same, if found loose.
  • By passing the arcing/red hot bolts in P.G clamps, T.clamps, etc using bypass jumpers.
  • Measurement of EHT clearances in load conditions.


EMERGENCY RESTORATION SYSTEM


The transmission tower cannot be designed to withstand natural calamities like storms, earthquake etc. due to resources and economy.
Breakdown of transmission line attended with conventional method required time of 6 to 8 weeks, which is time consuming. To overcome this problem is the use of emergency restoration system .


ADVANTAGES OF ERS; :


Light in weight, Foundation not required, less inventory, standardized and modular design, critical towers can be by passed very easily.



COMPONENTS OF ERS :


Foundationplate, Gimbaljoint, Column section, Guyplates, Insulators and hardware, Anchoring systems, Gin pole and Box sections.

DEPLOYMENT OF ERS:


  • Route alignment.
  • Computarised calculations.
  • Errecting structure.
  • Anchoring method.
  • Stringing of conductor.

STRUCTURE ERRECTION:


Four types of methods usually adapted for structure erection are,
  • Gin pole method.
  • By light duty crane.
  • Winch line method.
  • Helicopter method.


Anchoring systems:


Anchoring is very important for erection of stable ERS structure. Type of anchoring are,
  • Cross plate Anchor.
  • Screw or Marsh Anchor.
  • Dead weight Anchor.


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