Transformer Operational Principles, Selection and Troubleshooting

Introduction

Power and distribution transformers are among the most important and most expensive components of power systems, their failure can be very costly and dangerous for other major equipment and personnel alike besides imposing extraordinarily high costs on the electrical installation. The utilization of oil-filled and dry-type transformers is increasingly visible due to their outstanding characteristics. The design and operation of any transformer must fulfill certain requirements in order to withstand the electric, thermal, and mechanical stresses during its service life. Tests and maintenance of transformers according to the relevant standards are intended to ensure that a transformer passing them will give trouble-free service for many years under the conditions it is likely to experience after its installation.

The course will discuss:

• The design and construction details
• Selection methodology for dry type and oil-filled transformers
• Maintenance and commissioning procedures
• Troubleshooting checklists and failure analysis techniques
• Testing, diagnostics, and monitoring technologies

Objectives

Upon the successful completion of the workshop, each participant will be able to:-

• Describe the various classifications and types of transformer
• Appreciate the importance of transformer maintenance
• Analyze the various transformer test results
• Classify the transformer cooling methods
• Recognize the merits of transformer designs
• Understand the principles of operation and construction of the various types of transformer
• Identify the different components in the transformers
• Appreciate the testing and maintenance procedures for transformers
• Be familiar with construction of the transformer, transformer winding connections and cooling systems
• Recognize the effects of transformer off-load and on-load tap changers
• Comprehend site acceptance tests for newly installed transformers

Training Methodology

This is an interactive course. There will be open question and answer sessions, regular group exercises and activities, videos, case studies, and presentations on best practice. Participants will have the opportunity to share with the facilitator and other participants on what works well and not so well for them, as well as work on issues from their own organizations. The online course is conducted online using MS-Teams/ClickMeeting.

Who Should Attend?

This course is intended for technicians and maintenance staff that will be able to comprehend the types, construction, operations, function of transformers. This will enable them to carry out effective maintenance activities. This course is suitable for a wide range of professionals but will greatly benefit those who are working as Electrical Engineers, Maintenance Technicians, Electrical Supervisors, Engineering Professionals, and Managers of the electrical engineering department.

Course Outline

Day 1: Introduction, General Principles, and Classification

• General classification and types of transformer
• Transformer windings, the interconnection of windings and tertiary windings
• Parallel operation of transformers and paralleling requirements
• Standards for transformers, types, and requirements
• Transformer tapings and connections
• Ability to withstand short circuit, impedance Percentage, and Sound Level
• Case studies

Day 2: Transformer Constructional Details

• Transformer oil, characteristics, oil oxidation, and breakdown voltage
• Effect of oil expansion, breathing action, Buchholz relay, explosion vents
• Instrument transformers
• Transformers for Industrial Applications
• Internal and external cooling of transformers
• Construction and details of transformer Cooling systems

Day 3: Transformer Features and Thermal Performance

• Thermal performance and cyclic rating of transformers
• Transformer electromagnetic forces radial and axial
• Transformer winding and core construction
• Transformer tanks, radiators and tank Losses
• Sound and noise levels in transformers
• Gas-insulated transformers

Day 4: Transformer Operation and Maintenance

• Distribution voltage adjustment, off-load and on-load tap changing
• Earth fault and over-current protection of distribution transformers
• Transformer components maintenance
• Condition-based maintenance for transformers
• Guidelines on how to care for your distribution transformer
• Remote monitoring of transformers

Day 5: Transformer Testing and Troubleshooting

• Troubleshooting transformer faults
• Site acceptance tests
• Transformer routine tests
• Measurement of winding resistance and voltage ratio
• Insulation resistance tests
• Manufacturer and transformer type tests