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Current Network Condition. Characterised by aged, under designed and technically obsolete infrastructure Old-fashioned oil insulated switchgear – unreliable tripping times Inadequate (sometimes embarrassingly primitive) monitoring and protection systems Result - High number of outages
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Current Network Condition • Characterised by aged, under designed and technically obsolete infrastructure • Old-fashioned oil insulated switchgear – unreliable tripping times • Inadequate (sometimes embarrassingly primitive) monitoring and protection systems • Result - High number of outages • Plant maximum life cycle exceeded • SHER non-compliant • No system integration
Initiatives to Reduce Outages • Network Master Plan • Eskom (PTM) Engineering Studies • Detail Audits by OEM’s • Rotek Engineering • Siemens • ABB • Alstom • Hawker Siddley • Internal Audit • Focus on planned maintenance
NETWORK MASTERPLAN • PSW Consulting Engineers were appointed to assist in the preparation of Short, Medium and Long term Transmission and Distribution plans for the Midrand Area of supply. • NET Group Consulting Engineers were appointed to assist in the preparation of Short, Medium and Long term Transmission Plans for the entire Network excluding the Midrand Area of supply. They were also appointed to assist in preparing Distribution plans for three focus areas where loading and network problems were being experienced in the Siemert Road, Randburg and Roodepoort Areas. • Eskom (PTM) were also appointed to do pre-engineering studies at Fordsburg, Prospect, Delta, Kelvin and Orlando substations
Findings PSW Midrand Report • The infrastructure in Midrand supply area is relatively new with an average age of between 15 & 20 years. There are certain areas however which are appreciably older and will require upgrading and refurbishment in the Short term • The infrastructure needs to be extended to meet projected future load growth
Substation Transformers Overview • Detailed audit undertaken by Rotek and CP’s Test Branch • Significant number (52) of high risk transformers identified in terms of standard assessment parameters (moisture, DP, gases, acidity etc.) • Age profile of transformers indicates urgent need for refurbishment / replacement programme • Programme designed to eliminate backlog by 2010 (or sooner) thereby greatly improving reliability • Refurbishment programme to continue to reduce life cycles and conditions to acceptable levels
30 year life cycle Sample Transformers Age Profile
Transformer Refurbishment 5 Year Plan Note: Total Trfr = 250; Refurbished and maintained = 45; 52 to be addressed
MV Switchgear Overview • Detailed audit undertaken by OEM’s e.g. Rotek, Siemens • Significant number of high risk switchboards identified in terms of standard assessment parameters, particularly oil insulated units • Age profile of transformers indicates urgent need for refurbishment / replacement programme for switches >25 years • Programme designed to eliminate backlog by 2010 (or sooner) thereby greatly improving reliability • Refurbishment programme to continue to reduce life cycles and conditions to acceptable levels
Manufacturers recommend replacement > 25 years Age Profile All MV Switches
Protection Audits by OEM’s and Eskom • Audits on secondary plant equipment focusing mainly on protection were conducted by: • ABB • Siemens • Eskom PTM • Alstom • And Internal Staff
Findings • Main protection is prone to malfunction • Backup protection in most cases is out of specification • 70% of protection relays > 20 years old, no spares available • The suite of electro mechanical relays per line should be replaced with new electronic relays catering for the complete set of protection requirements, including disturbance recording. • Protection Schemes - 40 % of the Overcurrent and Earth Fault protection relays’ tripping characteristics had an error margin of approximately 60%. • Repairing and refurbishing of electro-mechanical relays is not a cost effective solution
Additional CAPEX Refurbishment Requirements Minimum required to clear backlog in 5 Years
Upgrade Programme and Assumptions • City Power has begun an intensive upgrade programme in order to achieve the following • Reduced average age of equipment – thru’ maintenance • Replacement of obsolete equipment – maintenance not feasible • Upgrade of overloaded networks in order to compensate for natural and anticipated load growth • Removal of equipment which is unsafe to operate • Achieve standardisation across all areas in order to reduce downtime and have more available emergency stock • Eradication of makeshift solutions • Ensure higher plant availability
Some Key projects for 2005/06 • Replacement and upgrade of substation transformers (17transformers ordered to be installed at: Westfield, Cydna, Hursthill, Rosebank, Roosevelt, Grand Central, Bryanston, Allandale, Brynorth, Randburg, Olivedale and Fairlands) • Protection upgrade at Kelvin and Prospect major intake points • Replacement of obsolete feeder boards • New substation at Bryanston to cater for pending re-zoning application • Continuous upgrade and refurbishment of MV and LV infrastructure
Key priorities for 2005/06… • Reconfigure 275 KV using Dead Tank Circuit Breakers and Pantograph Isolators to address outages at Fordsburg, Prospect and for Delta to be able to handle the surplus load • Installing prepayment meters in the identified areas in the South of Johannesburg • Increase continued partnership with OEM’s to help address critical network problems • Increase our focus on planned maintenance • The defective meters that have been identified and they will be replaced • Increase in the reduction of illegal connections in identified areas • A major focus will be dedicated to street lighting
2004/5 OLD JOHANNESBURG AREAS ALL AREAS
2004/5 Alexandra Area of Supply, incl electrification projects
