Protective Relay Technician Training



RELAYS 101 Three-Day Protective Relay Technician Training

Protective Relay Technician Calculators


RELAYS 101 - the App for iPad (just a few of the 30 pages shown)

RELAYS 101 - the App for iPhone (not shown)

Relays 101 Calculator #1Relays 101 Calculator #2Relays 101 Calculator #3Relays 101 Calculator #4Relays 101 Topic Page

This application for iPad gives you much more than great calculators.

After the 6 pages of calculators there is another page dedicated to a full-sized Apparent Impedance Diagram. These seven pages will give you most, if not all, of the calculations that relay techs need to get their job done.

Calculations include:

Symmetrical Components, Phase-to-Phase Calculations, Apparent Impedance Calculations, Watts/VARs/Volt-Amps, Polar-to-Rectangular Conversions, Rectangular-to-Polar Conversions, Reactance-Resistance-Impedance, Vector-Addition & Vector-Subtraction and a page to add up to 6 Vectors (as in a bus differential situation perhaps).

Then the iPad App diverges greatly from the iPhone App. (There simply isn't room on the iPhone for all of the information that follows!)

We give you half-a-dozen visual presentation pages of "In-Depth Topics". These pages lead you step-by-step through the relay tech calculations such as Positive Sequence, Negative Sequence and Zero Sequence Component Calculations. This way you not only have the calculators but you also gain the knowledge of "How-To" arrive at the values. Other step-by-step calculation pages are: Phase-to-Phase calculations, Polar-to-Rectangular (and back) conversions and (get this!) "Decoding SEL Event Report Phasors".

But we didn't stop there - additional "In-Depth Topics" are less calculation and more diagram-oriented. We have pages of diagrams that display relationships of the vectors that relay techs need to understand. A page called "Mho Math" is all about demonstrating how the simple Trigonometry that we need can be used to work your way around a "Mho Circle". A similar page attempts to bring understanding to the "Horizontal Characteristic" that is prevalent in the Reactance Relay. Other "In-Depth" Diagrams include: "LOP" (this one shows you why you might need to create a more realistic phase-to-phase test for your microprocessor relay), "Views of a Fault" (close up looks at preset faults from the perspective of Symmetrical Components, R-X Diagrams and Phasor Diagrams), "Practice Pythagorean" and "Directional-Distance Zones (21 Relays)". 

We have our standard text topics in there as well. Topics focus on how to calculate all of the values for yourself so that you gain understanding right along with having a handy relay-tech tool.

The calculators were the first issue of this great product.

The "In-Depth" pages came out as Version 2.

Version 3 makes our product an extremely valuable addition to a relay technician apprenticeship. Version 3 brings in the "Relay Testing Simulator" Pages!

10 different pages that present generic relays connected to generic relay test sets. See our test lead connections then adjust the relays' set points. On some pages there are various tests that can be run. Other relays have but a single test. Every test has its own generic connections shown. Your job is to set the relays then adjust your test set's voltage and current and watch for when the relay trip action occurs. This is a practical application to our Relays 101 Seminar's presentation on "Relays By The Numbers". The generic relays that are presented on the various Simulator pages include: 21, 24, 27 & 59, 40, 46, 47, 50 & 67N, 81, 87T and 87B.

This is very nearly an entire relay tech apprenticeship in an application. It's an APP in an APP!

If you recall our flagship product from 20 years ago ("Relay Training Center Software" for Windows) then you will recognize that this product is far superior in that we are finally able to let the user practice what we teach. We want to educate and assist the protective relay technician community. This product has been developed exclusively for the Apple Tablet series in hopes of hitting the next generation of relay techs.

Anyone can learn how to calculate these essential protective relay testing values.

Anyone can set up a spreadsheet to accomplish the task of calculating these values.

Or simply add this tool to your relay testing tool-kit and to your apprenticeship library.

Your relay test kit needs good test equipment, good knowledge and techniques and a good calculator.

We have been helping the community with teaching the knowledge and techniques, now add our calculator to your kit too.

iPad only - Requires iOS-7



And now the iPhone version has finally been released too! Same calculator functionality - adapted to smaller screens.

We started with the iPad version, but to fit the smaller screens and still leave all of the important calculations we had to remove the phasor drawings. Then with some minor re-arranginging of the input fields we managed to fit all of the same calculator functionality on the smaller phone screen.

An important relay technician tool is now available without internet, without spreadsheets and without your Laptops.

Optimized for iPhone-5, works on iPad, iPhone and iPod Touch.

Requires iOS-7

So sorry but the "In-Depth" and "Simulator" pages are not available for the iPhone.


These links will take you to the Apple App Store to review (and if you like to also purchase and download):

RELAYS 101- for iPad

RELAYS 101 - for iPhone

Contact us here for feedback.




If you don't have an iPad or iPhone then you always have your browser.

The calculator links below are written in Javascript, are part of this website and are free to use at anytime.

RTC (sm), Relay Training Center,, the content on this website, Relays 101 (C) the seminar, RELAYS 101 and Relay Tests the iOS Apps are all owned, maintained and copyrighted by Merle E. Ashton.