Hotline Washing and Maintenance
Hot Line Washing is a process of cleaning of insulators with the help of DM water /normal water, conductivity below 200 Micr0-mh0s, under live condition, without asking for shut down. Factors like salt, cement/lime, smog, vehicular emissions etc. affect insulator performance.
The method and equipment used for Hotline Washing was developed by Yashmun, and has been in use internationally for the last two and a half decades.This process entails cleaning of Insulators and Switchyards under live line conditions.
Whenever a jet of water is released in the air, the water particles split due to resistance. At a sufficient distance the jet moves in the form of small particles separated by air ,and the water path is not continuous. This forms a product similar to an aerosol, which in turn guarantees a sufficient electrical re-sensitivity, hence there is no leakage current . This is the principle behind the Yashmun method of Hotline Washing.
The high pressure jet is produced by means of a pump. Water with conductivity of 200 micromhos or less per cc is used for washing purposes up to 220 KV. Hence normal lake or river water or treated municipal water that has a conductivity of 90 to 120 micromhos can be used. In the case of 400 KV washing only by D.M water is recommended.
The specialized nozzle used is held at a distance stipulated from the live point so that no leakage current is encountered. For safety, leakage current in the water jet and nozzle is continuously monitored by means of a special detector, designed and made by Yashmun.
Electrically Operated Equipment
This is operated by a 415V, 3PH, motor. The unit consists of a motor driven high pressure pump with a starter flexible hoses and HP nozzles. All this is mounted on a trolley. A 2000 ltr water tank is placed on another trolley .The complete washing equipment is mobile and can be taken anywhere in the Switch yard or Tower location.
Truck Engine Operated Equipment
This equipment developed by Yashmun is used in instances where no power is available and is fully mobile, especially through hilly /jungle areas where Transmission lines pass. This equipment has been developed for the washing of Transmission line towers up to 400KV.In this equipment, the high pressure pump is operated by means of Power-Take-Off shaft (PTO). The Truck is provided with 5000 ltr of D.M or raw water. As the equipment is operated by means of the trucks engine there is no need for electricity.
Advantages of HLW
- No shut down/outages required
- Time and money saved as Power generation and Transmission are not disrupted while the job is done.
- Improves the di-electric strength of Insulators
- Increases the life of Insulators
- Reduces transmission loss
- Helps Switch yard/Transmission lines function smoothly.
- Avoids tripping of the line due to contamination of the insulator.
Due to the increasing complexity of transmission networks, coupled with inter regional /inter State ties, transporting of large quantum’s of power has rendered shut-downs on Transmission lines/stations almost impossible, thus rendering a need for live wire maintenance technicians. A network of 220 KV and 400KV Transmission lines form the backbone of the Transmission network. Power flow from these networks are monitored and regulated by National / Regional / State load dispatch centers.
It is obvious that a constant supply of electricity is required by consumers and for this an almost un- interrupted stable availability of Transmission lines is required. Providing redundancy in transmission lines could be a solution, which, however is a costly option. Therefore preventive maintenance, deploying live line maintenance techniques, proves the best solution.