Removal from Insulators
Ash that falls dry on dry surfaces is easily cleaned by air blasting or brushing. Ash that falls wet or is wetted before cleaning is not easily removed without high pressure water or hand cleaning. To prevent widespread power outages ash should be removed from electrical supply facilities as soon as possible and from the most sensitive areas first.
The washing of insulators should start from the bottom up to minimize the chance of wet reworked ash forming a sufficient cover to induce flashover. If possible de-ionized water should be used. Suggested methods for the protection of electricity supplies include:
- Immediately after an ashfall, dust, sweep, and blow ash from electrical equipment at substations.
- Shut down all electrical systems (by throwing the main circuit breakers) before any attempt is made to clean or service them.
- Remove dry ash immediately from the most sensitive systems by blowing it off using air pressure of 30 psi or less, to avoid a sandblasting effect. Be careful not to blow the ash to other places that should be kept clean. Vacuum ash when possible and change filter bags often.
- Clean electrical components such as small motors and light bulbs, as they will generate excess heat when blanketed with dust. The excess heat can cause fires and short term operating life.
- Avoid saturating electrical components when hosing dust off. Many of these systems can handle rain and moisture, but not the effect of water jets from hoses.
- Check for trees heavily loaded with ash near power lines.
- Check and keep insulators clean. Ash that has hardened may require special cleaning methods such as hand cleaning or water jetting.
Protect backup and auxiliary units to avoid starting problems when they are activated.
- Maintain protection and cleaning programs continuously until the threat of windblown ash is over.