TB Bushfire Defect Prioritisation

Transcription

1 Purpose TB-0183 Bushfire Defect Prioritisation The purpose of this technical bulletin is to inform staff and/or contractors of the requirements for the prioritisation of bushfire defects identified during the pre-summer bushfire inspection (PSBI). Background In accordance with MMI0001, a pre-summer bushfire inspection is carried out annually on assets located in bushfire prone areas. Currently, MMI0001 provides some guidance to prioritisation of defects. Requests have been made to provide a standalone PSBI defect prioritisation list with further clarification of bushfire defects. Actions The bushfire defect list (appended) shall be used to prioritise defects identified in the PSBI. All defects shall be assigned a 1 month priority unless it poses an immediate safety or fire risk (in which case it shall be assigned a 48 hour priority). Note that regional staff can modify the prioritisation of a defect after reviewing the defect photos and reassessing the risk of the defect. It is emphasised that all bushfire defects must be rectified before the start of the bushfire season (October 1), irrespective of the above. Contact: Andrew Tang Phone: Date: 17 March 2015 Authorised by: Jude Perera, Manager Primary Systems & Barry Lowe, Manager OLI/GLI 51 Huntingwood Drive, Huntingwood NSW 2148 Telephone: Fax: (02) Postal Address: PO Box 811 Seven Hills NSW Page 1 of 1

2 Bushfire Defect Prioritisation Bushfire defects must be prioritised appropriately to ensure that they are rectified before the start of the bushfire season (October 1). All defects listed below shall be assigned a 1 month priority unless it poses an immediate safety or fire risk (in which case it shall be assigned a 48 Hr priority). Note that regional staff can modify the prioritisation of a defect after reviewing the defect photos and reassessing the risk of the defect. For vegetation defects, refer to the Vegetation Management Common Requirements. Pole (all types) defects Vertical Alignment Any pole lean or bend, where the vehicle or electrical clearance has been compromised introducing a bushfire risk. Evidence of pole foundation failure or imminent pole failure. Foreign Objects Birds nests electrical clearances compromised. Timber pole defects Pole cap Loose pole cap (that can potentially fall onto mains). NOT A PSBI DEFECT: Missing pole cap, or lose pole cap that cannot potentially fall onto mains. Sapwood Sapwood is in contact with conductors Sapwood is loose, has the potential to fall onto mains (or compromises clearances) NOT A PSBI DEFECT: Sapwood is loose, but does not compromise clearances.

3 Knot holes Knot hole(s) with significant rot damage and the visual inspection indicates that the pole may fail. Possible indicators are fruiting bodies and rot. Follow up pole-top inspection required to determine the serviceability of the pole. Pole hardware defects Crossarm Significant decay with holes that can be seen through or major splitting that compromises mechanical strength. Failure is imminent. Crossarm deterioration. The top condition of the crossarm is difficult to determine from ground level, but it is likely that the deterioration seen from ground level warrants replacement. Crossarm has rotated and insulator is under strain, for: A single brace construction, where the brace is buckled, loose or missing. A two brace crossarm construction, where both braces are buckled, loose or missing. Crossarm has not moved, for: A single brace crossarm where the brace is buckled, loose or missing. A two brace crossarm, where both braces are buckled, loose or missing A two brace crossarm, where one brace is buckled, loose or missing. LV porcelain insulator Failed insulator/tie and conductor is resting on crossarm. LV ties are loose Major cracks NOT A DEFECT: Minor to moderate cracks or chips, which is unlikely to compromise conductor security. Leaning insulator, compromising electrical clearance. NOT A DEFECT: Minor insulator lean that is not compromising electrical clearance, nut is still fastened and no elongation of the bolt/pin hole. HV and transmission porcelain insulator Failed insulator/tie and conductor is resting on crossarm.

4 HV ties are loose Major cracks. Minor to moderate cracks or chips. Leaning insulator, compromising electrical clearance. NOT A DEFECT: Minor insulator lean that is not compromising electrical clearance, nut is still fastened and no elongation of the bolt/pin hole Polymer insulator Polymer insulator with complete shed reduction. Polymer insulator with 20% or greater reduction in electrical creepage distance due to shed damage. NOT A DEFECT: Polymer insulator with less than 20% reduction in electrical creepage distance due to shed damage. Polymer insulator with electrical tracking. Polymer insulator with exposed fibreglass rod. Polymer insulator with sheath damage. NOT A DEFECT: Polymer insulator with mould, fungus or insect activity. Nuts, bolts and pins Kingbolt nut is missing (urgent if there is a gap between the crossarm and the pole). Pin insulator with missing nut. Nut is loose and the thread of the bolt cannot be seen past the nut. Nut is loose and there is minimal amount of thread remaining past the nut. NOT A DEFECT: Nut is loose, but there is significant thread remaining and the security of the hardware has not been compromised. Insufficient thread remaining past the nut due incorrect installation. Cables Loose or heavily rusted fittings. Earthing Frayed or broken earth wire for regulator, pole substation, SWER or air break switch.

5 Multiple stolen overhead earth wires stolen on the same feeder. Frayed or broken earth wire for UGOH, recloser, load break switch or overhead earth wire. Contact with earth wire is possible. NOT A DEFECT: Major batten damage, but contact with earth wire is unlikely. NOT A DEFECT: Minor batten damage, and human contact with earth wire is unlikely Surge Diverter Brown porcelain surge diverter. Loose earth or line connection. Earth lead hanging down from base of the surge diverted, indicating unit failure. Cracked, chipped or evidence of electrical tracking refer to insulator defects under pole mains and hardware defects. Stay pole,ground stay and stay wire Stay wire has slipped, slackened or crushed the pole, and the alignment of the pole indicates that failure could be imminent. Stay wire has slipped, slackened or crushed the pole, and the pole foundation is not compromised. NOT A PSBI DEFECT: Stay insulator damaged / incorrectly installed NOT A PSBI DEFECT: Missing cattle guard in rural area. Stay pole defects treat as per Wood Pole defects Conductor defects Insulated mains HV ABC and CCT insulation has degraded and bare conductor can be seen. HV ABC and CCT insulation showing signs of degradation. LV mains (including service and consumer mains) insulation has degraded and bare conductor can be seen. Bare mains Broken, frayed, bird caged or split conductors.

6 Rusted steel conductor with flaking and/or rust. Incorrectly fitted helical termination that is free to move under wind conditions. Foreign objects (see SWM 6.014) Foreign objects on mains which is compromising public safety (for example, object is in reach of people or can interfere with traffic). Foreign objects on mains which are compromising electrical clearance between one (1) conductor and a timber crossarm and/or pole. Foreign objects on mains which is compromising electrical clearance between phases. Examples include kites, sneakers, fence wire and animals. NOT A DEFECT: Objects on mains which: a) Pose no public safety risk b) Does not compromise electrical clearance. For example, shoes on mains. Electrocuted/deceased animals on mains. Vibration damper Missing or incorrectly fitted (required for spans greater than 300m). Low voltage spreaders Low voltage spreader missing. Low voltage spreader with splintering. Pole substation defects Cracked, chipped or evidence of electrical tracking on bushing treat as per insulator defects under Pole and Hardware defects. Shroud missing or deteriorated. Tank Major oil leak, signs that a significant amount of oil has been lost (for example, oil on ground, or a dead patch of grass).

7 Active oil leak, indicated by a shiny appearance of the leak. Pitting, flaking or major corrosion. NOT A DEFECT: Surface rust. Jib-arm and box-arm Split or deteriorated treat as set out by the crossarm defects under Pole and Hardware defects. Dropout fuse Dropout fuse assembly is broken. Dropout fuse has spark arrestor. Air Break Switch/Underslung isolating links Insulators Cracked, chipped or evidence of electrical tracking on insulators refer to insulator defects under Pole and Hardware defects. Bonds/Connections Loose connection. Broken strand with minimal impact on electrical properties. The bond is not under tension so failure is less likely. Air break switch specific defects Visual or audible arcing is present. Contacts are not aligned correctly (arcing, burnt). Incorrect position of arcing horn. Isolating link specific defects Isolating link not attached correctly and is free to move.

8 Load break switches Bushings Cracked, chipped or evidence of electrical tracking on bushing treat as per insulator defects under Pole and Hardware defects. Load break with low gas Red low gas interlock disc is visible through view port.