Where Transformers Sit and What They Do

This course is for electrical technicians, supervisors and engineers who operate, maintain or are responsible for power and distribution transformers. It assumes you know basic three-phase principles. It moves from roles and ratings, through construction, loading and protection, to tap changers, testing, commissioning and managing a transformer over its whole life.

A typical oilfield or process site has dozens of transformers. They look similar from the outside, but they do different jobs, and each job brings its own operating and maintenance concerns. Recognising the job is the first step in judging any reading or alarm.

Why the role matters

Case 1. A drive transformer runs hotter than a distribution transformer of the same rating and load current. A technician suspects a cooling fault. The real cause is harmonic heating: the drive transformer was specified for it and is running normally. Knowing the role prevented an unnecessary outage.

Case 2. An earthing transformer's neutral resistor is found disconnected during an inspection. The system had been running unearthed for months without anyone noticing, because the earthing transformer carries almost no current in normal service. A second earth fault would have caused a phase-to-phase fault. Earthing transformers need inspection even though they appear to do nothing.