Switchgear (and circuit breakers) and transformers are critical components in electrical distribution systems and their operation significantly affects the overall performance of the system. This course will discuss the application, installation, maintenance and testing issues relating to medium and high voltage switchgear, circuit breakers and transformers. Low voltage switchgear will also be covered and you will receive a thorough grounding in switchgear theory and standards. You will gain a solid understanding of the issues associated with the proper application, installation and maintenance of these critical items of equipment with an overriding emphasis on safety. The emphasis is on medium voltage (referred today as high voltage) switchgear which represents most of the switchgear installed on electrical distribution systems. The focus is on air blast, oil, SF6 and vacuum circuit breakers.

Case studies covering the main manufacturers' equipment will illustrate the important practical principles. Other power system protection components will be discussed as well to ensure that switchgear is understood in the correct context. Installation of high voltage distribution and transmission equipment has increased significantly over the years due to ongoing global demand for power. As a result, the need to ensure reliability of operation of power systems is paramount. Power transformers are among the most important and most expensive components of power systems. Their failure can impose extraordinarily high costs on plants, factories and utilities of all descriptions. It is critical that all personnel operating and working with such equipment have a sound knowledge of their operational requirements and maintenance.

This practical course provides knowledge on both the theory and operation of Power Transformers. The course will develop and enhance an understanding of what is involved in the maintenance of these essential components of the power systems, through the tips and tricks learnt and developed by some of the world's pre-eminent electrical engineers.

YOU WILL LEARN HOW TO:

  • Describe the fundamentals of operating switchgear and circuit breakers
  • Select appropriate type and rating of circuit breakers and switchgear
  • Understand the operation of switchgear components (CTs, VTs, relays and cable terminations)
  • Describe the principles of operation of power transformers
  • Identify and apply the different transformer types
  • Set up simple transformer protection schemes
  • Detail power transformer testing procedures
  • Manage power transformer breakdowns to minimise disruption
  • Detail safe working procedures in switch rooms, indoor and outdoor substations
  • Draw up simple operational policies for safety rules
  • Detail practical maintenance strategies for switchgear and transformers 

Course Outline

MODULE 1: INTRODUCTION TO SWITCHGEAR AND TRANSFORMERS

  • Single line diagrams
  • Active and passive network components
  • Circuit breaker utilisation
  • Alternative forms of MV switchgear – ring main units and load breaking/fault making switches
  • Fuse switches
  • HV fuses in combination with, and as alternatives to circuit breakers
  • Auto-reclosers and auto-reclose operation

MODULE 2: APPLICATION OF SWITCHGEAR

  • Principles of current interruption
  • Plain break circuit breakers
  • Bulk and small oil volume circuit breakers
  • Turbulator (explosion pot)
  • Operating mechanisms
  • Transfer earth circuit breakers
  • Air break and air blast switchgear
  • SF6 and vacuum
  • Switchgear in association with isconnectors
  • Fixed and withdraw-able designs
  • Switchgear standards
  • Factors affecting switchgear selection

MODULE 3: SPECIFICATION OF SWITCHGEAR

  • Switchgear ratings - highest system and impulse withstand voltages, load and short circuit currents
  • Simple and complex protection systems
  • Switchgear ancillaries, measurement CTs, VTs and relays
  • Cable terminations
  • Indoor and outdoor operation
  • Substation and switch room layouts and design
  • SHORT CIRCUIT TESTING
  • Symmetrical and asymmetrical breaking
  • Make and break operations
  • Understanding test oscillograms
  • Case study - Specification for a 132 KV Switchboard

MODULE 4: SAFETY POLICIES

  • General safety precautions and the use of personal protective equipment
  • Principles of safety rules
  • Principles of personal authorization
  • Operative training for safe operation of switchgear
  • Isolation in a circuit breaker context
  • Safety documentation
  • Operational and safety locking, caution and danger notices
  • Work safety in a substation environment
  • Safety interlocks
  • Substation alarms
  • Individual study tasks and presentation - safety policies in my company and how they might be  improved

MODULE 5: OPERATION OF MODERN SWITCHGEAR

  • Case Studies
  • Sprecher and Schuh
  • Schneider
  • ABB
  • Siemens
  • ASSETS MANAGEMENT IN A SWITCHGEAR CONTEXT
  • Principles of time and condition based asset management
  • Asset registers
  • Asset management systems

MODULE 6: DIAGNOSTICS, TESTING AND MAINTENANCE

  • Switchgear inspection methodologies
  • Partial discharge measurement and survey
  • Timing tests
  • Thermovision
  • Mechanisms of deterioration
  • Principles of circuit breaker maintenance
  • Maintaining oil circuit breakers
  • Contact maintenance and contact wipe
  • Oil testing
  • Maintaining vacuum circuit breakers
  • Maintaining SF6 circuit breakers
  • SOPs and DINs
  • Switchgear defects and defect control Systems

MODULE 7: TRANSFORMERS' MAIN FUNCTIONS AND CLASSIFICATION

  • Construction (shell type and core type)
  • Classification and type in relation to insulation, windings, core, cooling systems, voltage level, sizing, tank and breathing action
  • Transformer parts
  • POWER TRANSFORMERS AND SAFETY
  • How to install, operate and work with high voltage power transformers safely
  • Earthing of HV transformers

MODULE 8: TRANSFORMER THEORY

  • Electrical values and their definition in a power transformer - voltage, current, number of turns,  impedance and their interrelation
  • OPERATION OF POWER TRANSFORMERS IN A POWER SYSTEM
  • Thermal performance, loading, paralleling, tap-changing, connections and vector groups

MODULE 9: POWER TRANSFORMER PROTECTION

  • Surge protection
  • Protective relaying (differential, over-current and earth fault)
  • Buchholz relay and pressure relief relay
  • Thermal devices and instruments (oil temperature alarm and trip, winding temperature alarm and trip)

MODULE 10: AUTO-TRANSFORMERS, GENERATOR TRANSFORMERS, UNIT TRANSFORMERS AND STATION TRANSFORMERS

  • Design criteria
  • Specifications

MODULE 11: OIL QUALITY

  • Oil contents: water, acidity and dissolved gas
  • Oil tests: dielectric breakdown, moisture, resistivity, interfacial tension, specific gravity, power factor and furan analysis
  • Recovery voltage measurement test

MODULE 12: POWER TRANSFORMER ELECTRICAL TESTS

  • AC Tests:
  • Power factor tests (insulation, oil, and bushings)
  • Single phase excitation current test
  • Transformer turns ratio test
  • DC Tests:
  •  Insulation resistance test
  • Dielectric absorption test
  • Polarization index test
  • Step voltage test
  • Hi-pot test
  • PREVENTATIVE MAINTENANCE ON POWER TRANSFORMERS
  • Techniques to improve life expectancy


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Boredom can be a real danger, however, we use an interactive approach to our e-Learning – with live sessions instead of recordings.  The webinar software allows everyone to interact and involves participants in group work; including hands-on exercises with simulation software and remote laboratories where possible.  You can communicate with text messages, or live VoIP speech, or can even draw on the whiteboard during the sessions.

 

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