Whether you are new to the industry or are well seasoned and want to review some of the basic information that you learned in the past, these courses and lessons will clearly outline what you are looking for. “Power Systems Electric” is On-Line training that bridges the gaps between textbook theories and practical power systems experience. As a retired electrical engineer who has gone through the experience of developing a career in electrical power systems, I know how frustrating it can be to try and find the answers, so I put together these courses that I feel would have been a major help to me in my development. I have also taken suggestions from students of what they would like to see in addition to these courses which I have given live in person.

Basic Electrical Learning

For those new to the industry, there is a beginner’s group of courses that cover the “Fundamentals of Electricity ” including DC and AC Circuit Analysis. These lessons examine such basics as Ohm’s Law, Series, and Parallel Circuits. The first, and perhaps most important, relationship between current, voltage, and impedance, “Ohm’s Law”, and its relevance to Series and Parallel Circuits. Subsequently, this will lead to the development of Kirchhoff’s Laws as they help to further analyze Network Analysis & Metering Circuits.

Conductors and Insulators are investigated along with their connected components, Capacitors, Inductors, and how they are influenced by Electromagnetism.

Alternating Current (AC – an electric current that periodically reverses direction) is the form in which electric power is delivered to businesses and residences, and it is the form of electrical energy that consumers typically use when they plug kitchen appliances, televisions, fans, and electric lamps into a wall socket.

The abbreviations AC and DC are often used to mean simply alternating and direct, as they are applied to current or voltage.

These AC courses deal specifically with sinusoidal waveforms and will provide the student with the basic understanding of working with circuits involving Alternating Current, which includes sinusoidal waveforms, vectors & phasors, reactance & impedance of R,L,C circuits, as they relate to the basic laws and theorems of electricity. This includes working with AC Power, Power Factor, Resonance, Complex Numbers, Reactance, and Impedance

Advanced Electrical Learning

These Courses involve subjects such as “Short Circuit Analysis for HV Three-Phase Systems ” which introduces the student to the basic concepts of fault studies on a high voltage three-phase system. System modeling is then used in order to aid in this process, with the ability to move between asymmetrical and symmetrical systems. With hey Searle and extensive study of “Per Phase” & “Per Unit” methodologies system faults are analyzed with the use of symmetrical components.

“A Per-Unit System ” is the expression of system quantities as fractions of a defined base unit quantity. Calculations are simplified because quantities expressed as per unit do not change when they are referred from one side of a transformer to the other.

In these courses, you will learn exactly what Per Unit Analysis is, the main advantages of using it, how manufacturers of equipment use and rate their products, and the technique of converting to and from the Per Unit system.

Several examples of working with Per Unit are demonstrated in this crisp clear presentation. When you finish you will have a though understanding of this subject.

It is important for all power engineers and technicians to be familiar with the concept of Per Unit as it is being used and referred to every day in power flow, short circuit evaluation, and motor starting studies.

The method of “Symmetrical Components ” is used to simplify asymmetrical three-phase voltages and current analysis by converting the unbalanced system into two sets of balanced phasors and a set of single-phase phasors, or symmetrical components. These sets of phasors are called the positive, negative, and zero sequence components.

An understanding of this method is essential for the understanding of fault analysis and modern-day protection schemes. These courses will provide you with the knowledge to comprehend the concept and how it is applied.

Supplemental Electrical Lessons

In all power electrical analyses, the student will encounter special Trigonometric and Mathematical identities and equations. This site contains special supplemental lessons that zero in on those identities and equations. For example, there are lessons that take you from the “Fundamentals of Trigonometry ” to the more sophisticated requirements in electrical engineering. As you work and study in electrical engineering you are going to run into proofs and equations that are based on trigonometry. A good example of this is when studying AC current, voltage, and impedance calculations, phasors or vectors are used and combined mathematically. Further adventures into complex power will also require a knowledge of trig functions and identities. As a student of this course, you will be introduced to these or at least re-introduced to these that may have been long since forgotten.
In mathematics, “The Derivative of a Function ” of a real variable measures the sensitivity to change of the function value (output value) with respect to a change in its argument (input value). Derivatives are a fundamental tool of calculus. For example, the derivative of the position of a moving object with respect to time is the object’s velocity: this measures how quickly the position of the object changes when time advances.

Specialized Electrical Lessons

Specialized lessons include the “Protection & Control(P & C)” principles of high voltage stations. HV Bus Differential Protection is studied along with restrictions due to CT saturation & mismatch and its solution, “Restraint Differential Protection”.

High Voltage Circuit Breakers are examined as to the various Types (Oil, Vacuum, Air Blast, SF6), their Controls as well as 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.

Other lessons include the study of “Transformers ” including core construction along with losses, cooling, and mitigation techniques. Three-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.

Lastly, there is a special section dedicated to “Single and Three-Phase Metering “, including old analog and new digital kilowatt-hour meters.

Conclusion

Regardless of whether or not you are new to the industrial power system, you’ll find what you’re looking for on this site in the way of training. In order to review or select any of these courses, left-click on any of the blue highlighted hyperlinked words of this posting or on “14 Courses Available” from the top menu of the landing page. All of the courses have a free introduction

As a bonus and in the way of a thank you, for your interest in PSPT’s WEB (and Blog) page, I’m making available my 50-page “Electrical Power” crib sheets. These were prepared for use with my courses that are available on this site. There is one section associated with each course and is extremely valuable while viewing the course, as well as a recall of the pertinent formulas and information after the fact. The contained information is also useful during any technical career as a quick reference from time to time. Simply click here or on the picture to the right to be taken to where you can download this item.

August 28, 2024

Blog #28 - Y - Y or Star Star Connected Power Transformers

August 28, 2024/ Graham VanBrunt

Star - Star (or sometimes called Y – Y) Connected transformers can deliver two voltage levels (phase to phase or phase to neutral) on both the primary and secondary. Also the terminal bushings can be gradient insulated and hence are less expensive to manufacture...with this type of connection...One terminal of the Primary terminals is connected to the system (Lines, Busses etc.). The other terminals are connected together and form a primary neutral. Similarly on the secondary, one terminal is connected to the LV system (Lines, Busses etc.). The other terminals are connected together and form a secondary neutral.

The high voltage H1 terminals are connected to individual phase conductors and the high voltage H2 terminals are connected together to form the neutral. The low voltage X1 terminals are connected to individual phase conductors and the low voltage X2 terminals are connected together to form the neutral. The transformer having its H1 terminal connected to the R phase is referred to as the red phase transformer. Likewise the transformer with the H1 terminal connected to the W phase is referred to as the white phase transformer (in this case I have coloured it green as white on white doesn't show up too well) and the transformer with its H1 terminal connected to the B phase is referred to as the blue phase transformer.

The vectors or phasors look like this…

Red phase both primary and secondary are in phase (disregarding the magnitudes). The White phase both primary and secondary are in phase (disregarding the magnitudes). The Blue phase both primary and secondary are in phase (disregarding the magnitudes). The H2 & X2 terminals form the neutral for both primary and secondary respectively. They are not necessarily connected together. The phasors are 120 degrees apart and rotating counter-clockwise.

Transformers for star connections with solidly grounded neutrals may be made with only one terminal brought out in a bushing and the winding insulation graded so that less insulation is used towards the grounded end of the winding. This results in considerable saving in cost of transformers.

In this blog, I want to introduce you to three vendors that I am promoting and will be promoting for the next little while. They happen to be three of the most popular power supply vendors on the market today. I will be providing links to their sites which if you use, you will be able to take advantage of a reduction in their cost price and as well…I will receive a small commission for promoting them but rest assured they are quality products. So stay tuned next three slides will provide the information that you are looking for.

First off is EcoFlow… I have introduced you to this vendor earlier and it is still one of the vendors that are on the top of my list. They have an exciting line of various power supplies which you can view and recognize a price reduction by going to this website…https://bit.ly/3MjaFTV… Remember that the address is case sensitive.

Next on the list is Anker… their range of products are similar but they also cater to the smaller output devices that are very portable. Again you can take advantage of some small sales by going to this WEB address…https://shrsl.com/4nisu

And finally there is Bluetti who also cater to the smaller output devices as well as having the larger standby power supplies… You can view their full range of products and again take it vantage of price reductions by going to this WEB address…https://shrsl.com/4nisy

My free “electrical crib sheets”…https://bit.ly/3VJle8z

See the full range of ANKER products…https://bit.ly/3YFQpmO

Directly access my Stan Store courses…https://stan.store/GVB