Below is a Self Rescue video taken during 400 kV training with NEPCO in Jordan.
Safe Hot Line Washing Requirements Part 1 – Conductivity and/or Resistivity
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?
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?
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
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.
Hot Line Insulator Washer – using a truck at 33 kV
Washing at 33 kV from an insulator washer truck.
In this video, the insulator washer is mounted on a truck chassis. The man stands on a platform and washes the insulators as the truck drives down the road. Using this method, they can wash over 300 structures in an 8 hour day!
For additional information, see our website: https://www.mitsacy.com
Mobile Washing System background
Due to the effectiveness and safety when washing, these mobile type washing units have become quite generalized and practiced around the world. As of 1985, there were quite a few number of countries, that still till this day, use mobile washing systems. These countries are: Argentina, Barbados, Canada, Chile, Colombia, Costa Rica, Egypt, Iraq, Iran, India, Japan, Libya, Mexico, Panama, Peru, Russia, Saudi Arabia, Syria, Thailand, Taiwan, United Arab Emirates, United States, Venezuela and Yemen. In the last 30 years, many additional countries have adopted the method of using mobile washing units in the maintenance of their network. Hence, it is safe to say that mobile washers are a necessary part of a reliable and effective live line maintenance program.
Trailer Mounted Insulator Washing Systems
Trailer mounted insulators washing systems are used primarily in electrical substations where it can be towed from one location to another for washing substation equipment. In many cases it is advantageous to use a trailer mount system because it has a lower profile and can be moved into better positions for washing than a chassis mount system. Trailers can have one or two axles depending of the load of water to be carried.
How to Prevent a Flashover when using an insulator washer truck live line
In order to prevent a flashover from occurring during insulator washing, the following points must be taken into consideration:
- Insulator washing should start on the lowest phase conductor.
- Always undertake the washing so that the spray does not fall on dirty insulators, as this may cause a flashover.
- Washing should always start at the bottom of the insulator, finishing at the top of the string.
- Always wash then flush the string.
- It is extremely important to consider the direction of the wind.
For additional information, see our website: https://www.mitsacy.com
Aerial Platform specs for Hot Line insulator washer
In general an insulator washer platform needs to be able to reach a height of the highest cross arm less about six meters. For example: if an insulator cross arm is at a height of thirty meters (30m) then the platform must be able to reach a height of 30 – 6 = 24 meters.
For additional information, see our website: https://www.mitsacy.com
