SAIEE Training Academy JHB | Substation Design & Equipment Selection

SAIEE Training Academy JHB | Substation Design & Equipment Selection
The workshop not only provides theory and examples but also practical insights from projects and technology management...
Event Name: SAIEE Training Academy JHB | Substation Design & Equipment Selection
Event Date: 10 September 2019
Starting Date: 10 Sep 08:00
Ending Date: 12 Sep 16:00
Event Type: CPD Course
Event Theme: Substation Design & Equipment Selection
Venue: SAIEE House, 18A Gill Street, Observatory, Johannesburg
Province: Gauteng
Cost: Please contact Roberto Benites for more info on this course
RSVP From: 17 May 2019
RSVP to: 09 September 2019
Event Contact: Roberto Benites
To RSVP: Click here

CPD Details
Activity Number: SAIEE-1865-V
Activity Title Substation Design & Equipment Selection
Activity Type Category 1
Provider SAIEE
Credits 3

SAIEE Training Academy JHB | Substation Design & Equipment Selection


SAIEE-1865-V, 3 CPD credits : Category 1


Electrical Substations play a disproportionately large role in the overall power system reliability.

Designers must balance technical performance with cost, whilst still considering maintainability and availability to keep the overall lifecycle cost low.

The design complexity is compounded by a multiplicity of switching configurations, and evolving switchgear technologies.

The workshop not only provides theory and examples but also practical insights from projects and technology management.

The material aims to demystify some of the confusion and contradictions by explaining why certain selections are made and the criteria they depend upon.


The course will cover the following contents:

A. Substation Electrical Configurations and Reliability

1. Substation Design Criteria

2. Different substation types: Transformation vs. Switching, Transmission vs. Distribution vs. Collector substation

3. Substation definitions according to Cigré: Components, Bays, Switchgear, Substation

4. Substation Components and Arrangements

5. Sub-transmission (132kV) substation example: Line Bay, Transformer Bay

6. Substation availability and reliability

7. Line bay topology for various levels of reliability

8. Maintenance requirements: Redundancy, Access, Disconnection and Earthing

9. Importance of Disconnectors

10. Maintenance requirements for different types of switchgear

11. Improving substation performance and reducing maintenance

12. Manual disconnection devices

13. Maintenance access

14. Basic substation electrical configurations e.g. Double vs. Single busbar

15. Sectionalised single busbar

16. AIS Bus section arrangement facilitating maintenance

17. Main and transfer busbar with bus-coupler

18. Ring or meshed busbar

19. Circuit-breaker-and-a-half

20. Double breaker

21. Relative cost and performance comparison

22. Standby and Mobile transformers for reliability and availability

23. MV switchgear layouts

24. Double vs. Single busbar

B. Substation clearances and spacings for AIS

1. Basic electrical clearances definition: Earth, Phase and Isolation (Disconnection)

2. Derivation of the clearances

3. Earthing philosophy and Temporary Overvoltage (TOV) effect on clearances

4. AIS vs. GIS clearances

5. Working or section clearances for maintenance

6. Derivation of vertical and horizontal safety clearances

7. Safety barrier

8. Earthing switches vs. portable conductors

9. Standardized electrical and safety clearances

10. Derivation of design spacings

11. Standardised design dimensions

12. Substation vertical profile (height)

13. Tension busbar conductor spacing

14. Rigid busbar spacing

15. Disconnector influence on transverse bay and bus dimensions

16. Standard bay spacings

17. Access for maintenance vehicles

18. Longitudinal spacing between equipment

19. Height of equipment connections

C Insulation coordination

1. Definition and basic principles of coordination

2. Standards and Practical approach

3. Overvoltage stresses

4. Transient overvoltages and wave-shape and tolerances for testing: Lightning, Switching

5. Origin of switching impulses

6. Temporary overvoltages, origins and effects

7. Statistical nature of overvoltages and insulation withstand

8. Insulation level vs. surge protection margin

9. U50 (CFO) vs. Insulation level (U90)

10. Insulation media classes and withstand characteristics

11. Large vs. small air gaps

12. Voltage classes MV, HV, EHV

13. CFO vs. air gap for Lightning and switching

14. Length of insulator and air gap clearances for overhead lines

15. Effect of relative air density (RAD) on withstand

16. Altitude and de-rating of insulation

17. Standards and correction for altitude

D. Overvoltage (Surge) Protection

1. Various protective devices and their protective characteristics (e.g. Spark gaps , gapped and gapless arresters)

2. Spark gaps or arcing horns

3. Spark gaps applications, coordination of spark gaps in system

4. Spark gaps risks and disadvantages

5. Use on line and modification for HV and EHV applications

6. Adjustable gaps

7. Protection of insulators

8. Reduction in CFO and performance of Overhead lInes with spark gaps

9. Modern gapless surge arresters

10. Construction and Voltage-current characteristic

11. Electrical selection of arresters

12. Protective margin

13. Residual voltage

14. Maximum continuous operating voltage (MCOV)

15. Rated voltage

16. Energy capability and line discharge class

17. Temporary Overvoltage (TOV) capability and MCOV

18. Arrester protective distance

19. Environmental and mechanical selection

20. Housing material and pollution performance

21. Explosion risk and reinforcement of arresters

22. Use of arresters for support

23. Assembly of arresters and grading rings

24. Substation arrester applications and installations

E. Electrical Ratings and Insulation Levels

1. Definition of IEC voltage classes

2. Standard IEC voltages

3. Rated voltage: Nominal and maximum system voltages

4. Rated frequency

5. Rated continuous current

6. Rated short-time current withstand

7. Rated peak current withstand

8. Arcing distance in AIS

9. Lightning impulse withstand

10. Switching impulse withstand

11. Power frequency withstand

12. Standardised insulation levels

F. Pollution Performance and Insulation Materials

1. Insulation creepage distances

2. IEC standard pollution severity classes

3. Specifying creepages: Specific and Universal creepage

4. Rationalisation of creepages based on environment and cost

5. Measuring creepage

6. Insulation materials and pollution performance

7. Properties of common insulation materials

a. Toughened glass

b. Porcelain

c. Composite polymeric

8. Hydrophobicity and effect on leakage current

9. Vandalism

10. Insulator cleaning

11. Coatings and shed extenders

G. Substation Busbar Design and Post Insulators

1. Considerations for bus design: Steady state, corona, short circuit

2. Tension (flexible) busbars: Features, advantages and disadvantages

a. Maintaining clearances

b. Substation profile etc.

3. Rigid busbar: Features, advantages and disadvantages

a. Flexible and rigid connections to bay equipment

b. Various indoor and outdoor examples

4. Tubular bus profiles and dimensions

5. Mechanical rigidity and deflection

6. Support of busbars on post insulators and disconnectors

7. Post insulator cantilever loads e.g. Short circuit forces and wind

8. Catering for thermal expansion

9. Aeolian vibration: Implications and mitigation

H. Flexible Conductors and Connectors

1. Flexible conductor: Properties, materials, types

2. Insulated conductors and connectors for vermin fault mitigation

3. Other mitigations for faults due to animals

4. Connectors: Properties, materials etc.

5. Connector types: Compression vs. bolted

6. Galvanic corrosion and joint compound

7. Development of hot connections

8. Bay stringing to cater for expansion

I. Power Transformers

1. Standards, definition and function

2. Transformer design challenges

3. The ideal transformer and ampere turns balance

4. Leakage flux and its implications (losses etc.)

5. Transformer types for power transmission and distribution

6. Double wound transformers

7. Auto-transformers

8. Core type transformers

9. 5 limb transformer

10. Shell type transformer advantages

11. Main components and function e.g. core, windings, paper, oil

12. Insulation types and materials

13. Insulation levels

14. Graded insulation

15. Temperature rise

16. Cellulose insulation and aging (degree of polymerisation DP)

17. Transformer conservator

18. Oil breathers and desiccants

19. Online monitoring and dissolved gas analysis

20. Dry type transformers: Applications, advantages, cost

21. Gas insulated transformers

22. Impedance and fault current

23. Vector groups

24. Parallel operation of transformers

25. Cooling methods and ratings

26. Losses and life-cycle cost evaluation

27. Load and No-load losses

28. Hysteresis losses, noise and core materials

29. Core construction (laminations and step lapping)

30. Continuously transposed conductor

J. Circuit Breakers

1. Standards, definition and function

2. Design challenges and evolving technology

3. Basic types: Live vs. dead tank

4. Dead tank features and advantages

5. Implications of cold operating temperatures: dielectric gas proportions

6. Single and three pole operation

7. Point on wave or controlled switching

8. Interrupting medium

9. Advantages of SF6

10. Advantages of vacuum interrupters

11. Contacts: Main and sacrificial contacts

12. Breaking chambers

13. Interrupter ratings and operating times

14. Grading capacitors and insertion resistors

15. Operating mechanisms

16. Disconnecting circuit breaker (DCB)

17. Specifying breakers

18. Ratings for 132kV

K. Disconnectors (Isolators) and Earth Switches

1. Standards and disconnector function

2. Disconnector types, features and advantages

a. Side beak

b. Centre break

c. Centre rotate

d. Vertical break

e. Knee type

f. Pantograph

3. Substation layout and disconnectors

4. User specifiable dimensions

5. Switching capabilities of isolators

6. Load contacts

7. Sacrificial / commutating contacts

8. Ganged and single pole operation

9. Manual and Motorised operation

10. Motor drives

11. Auxiliary contacts

12. Earthing switches

13. Integral earthing switches on disconnectors

14. Philosophy of Portable earth conductors vs. switches

15. Induction and trapped charge at Extra High Voltage levels

16. Maintenance

17. Specification for disconnectors

L. Metalclad switchgear for MV distribution

1. Standards

2. General features

3. Safety – Internal arc rating and detection

4. Comparison between SF6 vs. vacuum for MV application

5. AIS features and disadvantages (safety, environmental etc.)

6. Fixed pattern (GIS) advantages

a. Lifecycle cost

b. Performance

c. Safety

7. Emergency and mobile switchgear

M. Gas Insulated Switchgear

1. Definition and Major Components

2. GIS Construction

3. Network Integration and Connections e.g. Cables, AIS

4. Complete GIS Substations

5. Outdoor applications

6. Mobile GIS substations

N. Mixed Technology Switchgear

1. Different types of compact and combined switchgear

2. Compact AIS Modules

3. Development and Philosophy of Hybrid (Mixed Technology) Switchgear

4. Specifications and Equipment Rating Plates

5. Bay configurations

6. Functional components

7. Space savings with Hybrid switchgear

8. Further Hybrid examples

9. Maintenance philosophy

10. Comparison between technologies: Advantages and Disadvantages

11. Life-cycle costing comparison of the various technologies



· Engineers and Technicians in Plant, Project and Design, Power systems, Instrumentation & Control, Maintenance and Consulting

  • Engineering Managers
  • Safety Professionals

· Field & Service Technicians and Electricians

COST : Non-Member R10,600, SAIEE Member R7,500 (incl. teas, lunches and course material)

*Note: If proof of payment is received before commencement of the course, the following rates will apply:

Non-member R9,540 ; SAIEE member R6,750.



10-12 September 2019 : JHB

Registration : 08:00 – 08:30

Workshop : 08:30 - 16:30 (est.)




Gavin Strelec is a registered Professional Engineer since 2003, with 18 years of related experience in the Electricity Utility Industry with Eskom in South Africa. He has gained considerable experience in Substation Design as a Project Engineer, and subsequently design standards and equipment specifications as a Substation Technology Specialist concentrating on medium and high voltage switchgear up to 132kV. For several years he was acting as Eskom national specialist for several substation equipment commodities, eventually appointed as a Chief Engineer in Distribution Technology. He presently holds the position of Chief Engineer in Eskom's Research Department. He has recently obtained his MSc with distinction in Lightning Performance of HVDC Transmission lines.

He has been performing training seminars since August 2008 mainly on Substation Design but also Earthing and Overhead Line Design. He has presented in excess of 40 courses in various parts of South Africa, as well as the Democratic Republic of Congo, Ghana, Kenya and Uganda. His courses are always well received achieving high ratings from participating delegates. He uses many photographs and diagrams to communicate the principles and his presentation style is dynamic and engaging.




011 487 9042

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