ESCOM BY G.KALINDE SUBSTATIONS ENGINEER

Transcription

1 ESCOM BY G.KALINDE SUBSTATIONS ENGINEER

2 Balance Shareholder and Customer Interests Balance Short and Long Term Serviceability Understand trade-offs between Value and Risk Apply Asset Management Tools Build Asset Management Teams and Cultures Develop Investment and Operational Strategies

3 Impact of Change in Governance Profit Versus Service Approach Work Assets Harder Limit Maintenance Costs Changes to the resources available Changes to the Operational Accounting Procedures How to get the most bang for the least bucks

4 The Business environment has become tougher and the shareholder/customer conflict more evident. There is an enormous difference in the cost as opposed to the value of electricity. The value to the customer of un-served energy is many times its cost to the utility Customers are becoming more demanding in regard to the quality of supply. Cost of the loss of revenue is not always addressed

5 Transmission Coupling Transformers Redundancy usually built in to the network Manage the redundancy Loading rarely reaches rating plate levels Lightning and environmental surges prevalent Older designs often had more empirical margins

6 Generator and Industrial Transformers Redundant units rarely installed and commissioned Thermal loading regimes more onerous Consequential cost of a lost unit often higher Furnace transformers are subject to severe fault conditions and specially designed and customised

7 The Asset Management Approach varies from the Traditional Service at any cost approach so all the possible value must be extracted from the development and application of software tools and the development of an Assets Management Culture

8 Generally Accepted Municipal Accounting Practice often governs the accounting treatment of Assets An Asset is recognised as such if:- It is used for the production or supply of goods and services If it is to be used for more than one accounting period It has a useful life defined as: The period of time over which it is to be used is finite The number of similar units (of production) is expected

9 The carrying value in the books of account is generally the cost of acquisition or construction including: Site preparation costs Installation costs Professional fees Interest during construction is omitted in municipalities The carrying amount is reduced each year by the depreciation to allow for the reduction in value of the asset as it produces The residual value is the amount expected to be recovered when the asset is retired (may be positive of negative) Fair value is the amount which an asset could be exchanged between knowledgeable, willing parties in an arms length transaction

10 Some other issues: Impairment Revaluations Refurbishments and Maintenance The value of the transformers on a representative distribution utility is: 5% if the value of low volt systems is included in the asset base 13% if excluded The risk is to consequential rather than direct loss It South Africa Municipal Systems may be governed by GAMAP

11 Commissio ning Net Asset Cost 100% Transformer Life Cycle 75% 100% Planning and Engineering Maintenance Installation Retirement Revenue Earning

12 Draw your attention to the sensitivity of the value of the asset s life Any Life extension beyond that planned is a significant windfall for the utility Any failure by the transformer has massive risk implications Whilst transformer design and manufacture is a very mature industry, the estimation of remnant life is not yet definitive. System electrical and physical environmental conditions play an important role in the life cycle of a unit

13 A Number of Asset Management tools exist to attend to the various stages in the life of an item of plant. The management of the transformers life is the most significant and beneficial Others in this series of workshops have dealt with the benefits of: Corrective maintenance Time based maintenance Condition based maintenance Reliability centered maintenance Select a strategy which supports the asset you have in service and is appropriate to the units in your care

14 Component Risk Detection Rate Winding & Core 35% 70% OLTC 40% 75% Bushings 14% 80% Tank 6% n.a. Auxiliary 5% 100% ABB Statistics reported to Cigré

15 Insulation Systems Dissolved gas analysis On-line Off-line Furan analysis Paper samples need to be taken Degree of polymerization Power factor Etc.

16 Mechanical Systems Sweep frequency response analysis Core to earth resistance Oil leaks Electrical Systems Ratio Resistance Benchmarking Information Footprints Electric Utility Benchmarking Association

17 HV Voltage No of Units Failure Rate 123 kv % 245 kv % 400 kv % Average 245 & 400 kv % German experience reported to Cigré

18 HV Winding kV kv kV Numb er of Units Total Failures Failure s Forced Outages % Failure s 39 0 * 0 * % Source - Cigré

19 Age of the units (years) Winding Highest Voltage kv kv kv Numb er Rate Numb er Rate Numb er Rate % % % > % % % > % % %

20 HV Winding With OLTC Without OLTC kv 35<M<57 * kv 46<M<76 29<M< kv 30<M<150 45<M<120 M = Mean Down Time (Days)

21 Tan D Aged Oil, 0.5% Moisture Good Oil 1.3% Moisture PF = Measured DR 0.7% Moisture Frequency, Hz

22 The cost of the loss of revenue is complex since the revenue depends upon the possibility of supplying the customer from another route or generation source. The cost of the interruption to the client can, however, be some 200 times the cost of the energy as was bourne out during the breakdowns in Auckland and North America

23 Admittance Defect Unit Frequency

24 In terms of the whole network, asset values for transformers are relatively inexpensive whilst the risk and impact of failure are considerable. Money spent on the proper asset management of this asset class is important Cohesive strategies must be developed to integrate other Asset classes Software and hardware tools are constantly being developed Information gathering and archiving are vital

25 END OF PAPER THANK YOU