## The Complete Guide to the Square Root of Three in Power Calculations

Zach Stone, P.E. contacted me after I (Chris Werstiuk writing right now) posted my recent “Understanding the Great Leading vs. Lagging Power Debate” post because I had incorrectly defined Apparent Power. Thanks to his keen eye and knowledge on the subject, no-one who purchased The Relay Testing Handbook: Generator Relay

The Complete Guide to the Square Root of Three in Power Calculations

## Understanding the Great Leading vs. Lagging Power Debate

I once watched two engineers/technicians argue for two hours about what power definitions should be displayed on a HMI interface. One of them argued that VARs were being EXPORTED during lagging conditions, so a lagging current should be shown as POSITIVE VARS and Power Factor! The other argued that VARs

Understanding the Great Leading vs. Lagging Power Debate

## Use Sequence Components To Make Sure Your Relay Isn’t Disabled By Incorrect Phase Rotation

Did you know that a relay connected to, or set with, the incorrect phase rotation can disable its higher level functions? Did you know that the wrong phase rotation can make your relay testing worthless? Did you know you can quickly and easily tell whether the phase rotation is correct

Use Sequence Components To Make Sure Your Relay Isn’t Disabled By Incorrect Phase Rotation

## How to Perform an In-Service Protective Relay Meter Test

In-service protective relay meter tests are THE MOST important tests that should be performed on every digital relay. All of your offline relay testing is meaningless if: The CT/PT ratios are incorrect. The relay isn’t connected to its input signals (CTs/PTs). The relay is looking in the wrong direction. The

How to Perform an In-Service Protective Relay Meter Test

## Why Does My Open-Delta Connected Phasor Diagram Look Weird?

Meter tests on protected relays connected to open-delta connected PTs can be very confusing. I know I spent a LOT of time trying to figure out the values reported by my first open-delta connected relay during my first simple meter test.  The voltage and current phasors were completely out of

Why Does My Open-Delta Connected Phasor Diagram Look Weird?

## How to Understand and Determine Phase Rotation in a Power System

Understanding phase rotation is vital when connecting two systems together because the results can be catastrophic if someone doesn’t understand how to interpret phase rotation drawings. You would think something as important as phase rotation would have consistent terms across the entire industry. Unfortunately, you’d be wrong. Let’s start with

How to Understand and Determine Phase Rotation in a Power System