4.3 out of 5
21 reviews on Udemy

Electrical 3 Phase Power Transformers Fundamentals

The basic principles of high voltage transformers, from a protection & control perspective.
Graham Van Brunt P. Eng., B.Sc.
147 students enrolled
English [Auto]
Electromagnetism, Voltage & Current Transformation, Ratios and Polarity, Potential & Current Transformers, 3 Phase Transformers Construction, Transformer Classifications, Losses & Cooling, Per Unit Equivalent Circuits, 3rd Harmonic Currents problems, Tertiary Windings, The Buchholz Relay, Oil Analysis, Transformer Connections: Y – Y, Delta - Delta, Y - Delta, Y - Zig-Zag, Transformer Over-Current Protection, Transformer Differential Protection, Relays old and new

Electromagnetic forces interact with electrically charged particles and electromagnetic fields; this course will study how these forces lead to voltage & current transformation. Ratios and polarity is also studied leading to the introduction of potential transformers & current transformers, and their use in conjunction with the relevant instruments such as ammeters, voltmeters, watt meters and energy meters.

Transformer core construction along with losses & cooling mitigation techniques. 3 phase transformer configurations are studied along with harmonic distortion, CT saturation and on-load tap-changer problems and how these problems are dealt with. Over-current and restraint differential transformer protection is developed along with a look at some examples of ” Old School relays” as well as modern IDE (intelligent Electrical Devices) relays.

Transformer Connections: (Y – Y; Delta – Delta; Y – Delta; Delta – Y & Y – Zag Zig) are examined along with Transformer Clock System Vector Nomenclature.

Oil Analysis and the Buchholz Relay are also studied.

This section contains 9 lectures including the introduction.


This lecture is a preview of the course on power transformers

The Ideal Transformer

Here the student will be introduced to the basics of an ideal transformer, first reviewing electromagnetism, electromagnetic Induction, Faraday's & Lens's Law. Transformer turns, voltage & current ratios.

The Real Transformer

Here the student will move from the ideal to the real transformer including "losses". An "Equivalent Circuit" of a Real Transformer is developed.

Instrument Transformers
a ) Three Phase Power Transformers

This lecture introduces the student to Nikola Tesla's 3 phase system power including phase relationships. The main type of transformer connection configurations (Y & Delta) are presented then the Y-Y; Delta- Delta, Y-Delta; Delta-y & Y-Zig Zag transformers are studied. Per Phase and Per Unit equivalent circuits are introduced for each type of configuration.

b) Transformer Clock System Vector Nomenclature

Three phase Transformer Clock System Vector Nomenclature is described along with multiple examples of transformer configuration and connections.

Transformer Construction and Cooling

Power transformer construction is looked at including "core" and "shell" types. The various types of cooling are described along with the EEE Standard C57.12.00-2000 - four-letter designation.

Transformer Protection

The various types of transformer protection are introduced here including including fuses, instantaneous and timed over-current protection, differential & percent differential protection. Difficulties that tend to handicap the conventional transformer differential protection and some solutions... 

- Magnetizing inrush current during initial energization

- CT's mismatch and saturation

- Transformation ratio changes due to Tap changers

Transformer Relays

This chapter will look at some of the various types of relays out there from the "old school" relay, the (ASEA) Brown Boveri D21SE Two Winding Transformer Differential  Relay (which is still in use) as well as transformer management relays, the GE Multilin SR745; the Siemens 7UT51 and the MiCOM P632. The Buchholz Gas Relay is also reviewed along with Dissolved Gas Analysis (DGA).

You can view and review the lecture materials indefinitely, like an on-demand channel.
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4.3 out of 5
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6 hours on-demand video
Certificate of Completion


AulaGEO is a Ge-engineering specialized academy.

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