MITSA INTERNATIONAL

Live Line Specialty Tools & Maintenance

How can you prevent insulator Flashovers?

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There are several methods to clean insulators.

  • Hand clean- De-Energized The insulator is cleaned using a hand brush.  This is done de-energized.
  • Hand clean Energized – A cleaning brush is attached to a hotstick and the insulator is cleaned by hand.  This is typically only done for vented lightning arresters or in areas when wet/dry cleaning are not possible.
  • Wet clean –  This can be done energized or de-energized using a high pressure insulator washer.
  • Dry clean –  Can be done energized or de-energized using a dry washer.

For additional information, see our website:  https://www.mitsacy.com

Should an insulator washer truck aerial platform be insulated?

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In general, insulator washer truck aerial platforms are not insulated unless they are also used for live line maintenance. The reason why we do not insulate the platforms is because the wash guns and truck chassis should be grounded to the structure.  Adding an insulated insert is therefore unnecessary as it must be bypassed during the washing process.

For additional information, see our website:  https://www.mitsacy.com

Skid vs Trailer Mount Insulator Washing Systems

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Both the skid and trailer have their own advantages in having a mobile washing system installed on them. The basic skid package consists of all of the washer components. The water tanks size will simply depend on the load capacity of the chassis used to transport the washer. The advantage of using a skid is that it can be set on or taken off any chassis very easily with a crane, which allows the chassis to have other applications, primarily in substation applications. The washing trailer is the most utilized washer for substation work because it has a fairly good sized water tank – 6000 liters. The second most common reason why it is used is because it does not tie up the chassis for only use as a water tank. With the use of a truck or a tractor, a trailer becomes quite effective at being mobile and able to clean a substation. The trailer is also used for washing transmission lines with a chassis pulling the trailer. Often in this case the pulling chassis can be a mobile aerial lift, particularly for washing distribution network insulator, or in some cases a chassis equipped with an extra water tank.

Hot Line Washing Saftey Test – Part 3

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A third test was conducted on contaminated insulators. Firstly, they were flashed over, then washed, then flashed over again. During the process the voltage was noted when the second flashover occurred, thus establishing the effectiveness of the “washing”. An important note to add is that most of the insulators obtained full insulation ability.

The importance of having clean insulators stems in the issue of avoiding power loss due to leakage along the insulator chain. The testers had established that 1 milliampere would be the maximum acceptable limit of leakage current. Through a series of trials the optimal water pressure and distance had been found. Further, the testers also determine that special equipment had to be used in the washing. Initially fire and gardening hoses had been used, but due to the inability at being able to achieve the optimal pressure, hoses with smaller orifices, allowing greater pressure, were developed.

Do you need a Fixed or Mobile Washing System?

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In the field of live line maintenance there is a large variety of equipment used to wash insulators. Currently there are a few substation and special tower applications which possess fixed washing systems installed. However, for effective cleaning to occur there is a requirement for the insulator to be “hit” from varying angles at different lengths of time. The only achievable method of doing this with a fixed washing system requires a highly complex and sophisticated system, which ultimately is quite costly. The most effective solution to the highly complex and expensive fixed washing system is through the utilization of a mobile type washer which functions by either an operator-held or a single remote control nozzle.

Hot Line Washing Saftey Test – Part 1

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In order to assure that mixing water with electricity is a safe process, several power companies have run extensive tests on washing energized insulators. The first recorded tests were done in 1941, by Pacific Gas & Electric of California. In 1947 the same company re-conducted and documented the tests. They wanted to determine the following results:

  1. The true effectiveness of cleaning the insulators with water.
  2. Record the amount of leakage that had occurred through using different water streams.
  3. Test various nozzles sizes and shapes, different water resistivities and “new” water resistivity testers.
  4. Evaluate the economics of washing, using this method.

Why Use Hot Line Consulting Services?

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Many international utilities when first embarking on the concept of Live Line Maintenance put together a random tool list that they collect from various manufacturer’s internet website. They then publish a pubic tender for the supply of these tools. The tools are then purchased.

Do you see any problems with this approach?

Hot line tools manufacturers want to sell tools. When they publish generic tools lists they are a shotgun approach to what a utility might need. Hot Line Tools are getting more and more expensive every day. The quality and reputation of the tools varies form manufacture to manufacturer. In many cases, special tools are required. Who will specify and design these tools?

Using a qualified consultant who understand the tools and the jobs that the customer wants to do will always save money in the long run. The customer will spend less on tools and get what they need.

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