MITSA INTERNATIONAL

Live Line Specialty Tools & Maintenance

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.

Live Line Training in Jordan

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Between 2006 and 2012 we conducted multiple live line training programs in the county of Jordan.  During this period, we have trained linemen and engineers in safe working practices for Live Line Maintenance at LV (220/380V), MV (11/33 kV) and EHV (400 kV).

Our satisfied customers in Jordan include:

NEPCO (National Electric Power Company) – 28 linemen and engineers

IDECO (Irbid District Electric Company) – Over 60 linemen and engineers

EDCO (Electricity Distribution Company) – Over 60 linemen and engineers

Safe Hot Line Washing Requirements Part 1 – Conductivity and/or Resistivity

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For an efficient and safe washing of insulators, the water must have a minimum of 2540 ohm-cm or 100 ohm-in resistivity or a maximum of 400 micro-siemens conductivity. An additional note to this is that resistivity of water decreases as water temperature increases. Hence, it is important that the resistivity/conductivity of water be measured constantly. Normally, washer packages include “Constant resistivity monitors”, which notify the operator if water conductivity rises above a pre-set level. These monitors can be installed to automatically turn off the washer is this limit is reached. Portable meters are also available and can test the resistivity or conductivity of the water before filling up the tank.

 

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.

For more information on our services click here.

What composes an insulator washer system?

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All insualtor washer systems are composed of the following basic items: a water tank, a water pump, a water hose and reel, a wash gun, a fuel tank and a power source. Several of these components do vary, for example the smallest mobile washing unit has 950 liter water tank. Water tanks can be as large as 15,000 liters (if the chassis can support the weight).   All of the tanks are constructed of stainless steel and can be supplied with up to three hose reels with either 3/4″ or 1″  diameter hose. Nozzle sizes available vary with both 1/4 and 5/16 available. Although 1/4 is the standard nozzle size, 5/16 is far more effective in windy conditions. The fuel tank is typically about has 30 US gallon (113.562 Liters) capacity, and the independent power source can be either gasoline or diesel. The components can be installed on either a skid or a trailer.

Aerial Application for Skid Mounted Washer System

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A washer system mounted on a skid, may be placed on a chassis with an aerial platform or with a remote controlled hydraulically operated nozzle and mounted on a telescoping boom. This nozzle has the ability to move both vertically and horizontally, giving it a very good range of motion. The main use for this type of washer is on EHV (extra high voltage) transmission lines. Generally these washers have controls at the base of the boom. With washers on an aerial platform, control stations are provided at the base of the boom along with one on the platform to allow the user to wash manually.