Certificate in Circuit Breakers, Switchgear and Power Transformers – Safe operation and Maintenance

 

 

 

 

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.

 

 

 

 

 

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

Practical Exercise

 

 

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

Practical Exercise

 

 

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

Practical Exercise

 

 

 

Symmetrical and asymmetrical breaking

Make and break operations

Understanding test oscillograms

Case study - Specification for a 132 KV Switchboard

Practical Exercise

 

 

General safety precautions and the use of personal protective equipment

Principles of safety rules

Principles of personal authorisation

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

Practical Exercise

 

 

 

Case Studies

- Sprecher and Schuh

- Schneider

- ABB

- Siemens

Practical Exercise

 

 

 

Principles of time and condition based asset management

Asset registers

Asset management systems

Practical Exercise

 

 

 

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

Practical Exercise

 

 

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

Practical Exercise

 

 

 

How to install, operate and work with high voltage power transformers safely

Earthing of HV transformers

Practical Exercise

 

 

 

Electrical values and their definition in a power transformer - voltage, current, number of turns,  impedance and their interrelation

Practical Exercise

 

 

 

Thermal performance, loading, paralleling, tap-changing, connections and vector groups

Practical Exercise

 

 

 

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)

Practical Exercise

 

 

 

Design criteria

Specifications

Practical Exercise

 

 

 

Design criteria

Specifications

Practical Exercise

 

 

 

Design criteria

Specifications

Practical Exercise

 

 

 

Design criteria

Specifications

Practical Exercise

 

 

 

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

Practical Exercise

 

 

 

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

- Polarisation index test

- Step voltage test

- Hi-pot test

Practical Exercise

 

 

 

Techniques to improve life expectancy

Practical Exercise