Electrical Black Book

Electrical Black Book

Electrical Black Book (Coming soon)

To compute the efficiency of a transformer, the input power to and the output power from the transformer must be known. The input power is equal to the product of the voltage applied to the primary and the current in the primary. The output power is equal to the product of the voltage across the secondary and the current in the secondary. The difference between the input power and the output power represents a power loss. You can calculate the percentage of efficiency of a transformer by using the standard efficiency formula shown below:



Losses in the transformer arise from:

Winding resistance :

Current flowing through the windings causes resistive heating of the conductors. At higher frequencies, skin effect and proximity effect create additional winding resistance and losses.

Hysteresis losses :

Each time the magnetic field is reversed, a small amount of energy is lost due to hysteresis within the core. For a given core material, the loss is proportional to the frequency, and is a function of the peak flux density to which it is subjected.[18]

Eddy currents :

Ferromagnetic materials are also good conductors, and a solid core made from such a material also constitutes a single short-circuited turn throughout its entire length. Eddy currents therefore circulate within the core in a plane normal to the flux, and are responsible for resistive heating of the core material. The eddy current loss is a complex function of the square of supply frequency and inverse square of the material thickness.[18]

Magnetostriction :

Magnetic flux in a ferromagnetic material, such as the core, causes it to physically expand and contract slightly with each cycle of the magnetic field, an effect known as magnetostriction. This produces the buzzing sound commonly associated with transformers,[6] and in turn causes losses due to frictional heating in susceptible cores.

Mechanical losses :

In addition to magnetostriction, the alternating magnetic field causes fluctuating electromagnetic forces between the primary and secondary windings. These incite vibrations within nearby metalwork, adding to the buzzing noise, and consuming a small amount of power.[19]

Stray losses :

Leakage inductance is by itself loss less, since energy supplied to its magnetic fields is returned to the supply with the next half-cycle. However, any leakage flux that intercepts nearby conductive materials such as the transformer’s support structure will give rise to eddy currents and be converted to heat.

Three-phase transformer

A three-phase transformer is made of three sets of primary and secondary windings, each set wound around one leg of an iron core assembly.

Connecting Single-Phase Transformers into a Three-Phase Bank:

Power may be  supplied through a three-phase circuit containing transformers in which a set of three single  phase transformers is used. Using three single phase transformer becomes difficult to handle  especially because of size, weight and is less economical to use. When used this way, this arrangement is called a transformer bank.

When a considerable amount of power is involved in the transformation of three phase  power, it is more economical to use a three phase transformer. The unique arrangement of the windings and core saves a lot of iron, losses, space and money.

There are two configurations for three phase power:

1) Delta : In this three conductors are connected end to end in a triangle or delta shape.

2) Wye  : All the conductors radiate from the center, it means they are connected at one common point. The Wye  connected winding is often called a ” Star Connection “. It has four leads, three phase leads and one neutral lead, so it is possible to provide two voltages.

Possible uses of transformer combinations as follows:

  • Delta to Delta – use: industrial applications
  • Delta to Wye – use : most common; commercial and industrial
  • Wye to Delta – use : high voltage transmissions
  • Wye to Wye – use : rare, don’t use causes harmonics and balancing problems.

69 Responses

  1. is the electrical black book available for sale?


  2. Hi,

    Has this yet been published? If so where can it be ordered?



  3. Is this book available yet?? I am really interested in it

  4. Is there a book for instrumentation?

    • At this stage no instrumentation black book has been planed however, thank you for suggesting it. Hopefully it will become a reality in the not so distant future.

  5. Is this book for sale yet?

  6. Where to buy “ELECTRICAL BLACK BOOK”. in Canada.
    I live to Montreal, and how much?


  8. just wondering if the electrical black book has been released yet, if not do you know when?

  9. Hi! Could you please give us an idea of when to expect the release of the Electrical Black Book? Thanks!

    • Hi Aaron, The Electrical Black Book will be released in May through Reid Supply. Please check back in another month for updates.

  10. I heard there was also a HVAC black book going to be released – any info on when?

  11. Hi guys good news “Electrical Black Book” is out!!!!!!!!!!!!!!!!!!

  12. How long until we can expect an international or australasian version?

  13. Hi,

    Where can I buy this book in Canada? I think Reid Supply will ship to Canada, but if there is a Canadian supplier I’ll use them, it will be faster.


  14. Hi

    Just wandering how the Australian version is going and if it is available yet?


  15. can i please get uupdate on how the australian version is goin???

  16. Gday,
    Just wanting to know whether the Australian Electrical Black Book has been released and where it can be purchased from?

  17. Gday,
    Just wondering whether the Electrical Black Book Australian version has been released yet? And where it can be bought from?

  18. Where can i buy the Australian version of the electrical black book ?

  19. Has the Australian version been released?

  20. update on how the australian version is going? is it avaialable and where from? thanks.

    • Dear Matt, We are having some updated information regarding Australian standard and hope to have the book release in early 2013.

  21. do we have a date for the release of the australian version? this is a long time coming

    • Hello, the final Australian Edition proofs are being completed currently and we hope to have it to market within the next two months. We have noted your contact email and will let you know when it becomes available.

  22. can i be notified when the book will be released

  23. Hello
    Can you please emale me when the Australian version of the Electrical Black Book is available.
    Thank you

  24. Also another user chomping at the bit to get hold of the Electrical
    black book in Australia, please email me, tim@thinkots.com

  25. Please inform me when the Australian book is redy for release.


  26. any updates for the australian version of black book?

    • Hi Matthew, We have noted your email address and will email you when released. Thank you for your patience!

  27. Hi, could you please inform me when the Australian Version is available. Thank You

  28. I’m also interested in an Australian version. Looks like its a popular request.

    • We will let you know when it has been released!

      • Been a long long wait I know rules an regs are constantly changing but im surprised at the lengthy time to publish the first edition! Considering the interest theres a bit of money in this book

  29. Another keen Australian waiting for this release, 3 years and counting.

  30. Can I Buy This Book from thiseAD

  31. Can I pre pay for the Australian electrical pocket book I need 3 copies ASAP
    Great product

  32. Thank you for your interest! We have noted your e mail and will keep you informed.

  33. have used the other two countless times. They are great! Any news on when the Australian electrical version will be available? I have noticed that it has been a couple of years now…

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