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

Three phase voltage phasor diagram showing P-P is P-N times the square root of three

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

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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

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Understanding the Great Leading vs. Lagging Power Debate

How to Perform an In-Service Protective Relay Meter Test

1-Simplified_three-phase_power_system_in-service_protective_relay_meter_test_Scenario_1

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

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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

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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

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How to Understand and Determine Phase Rotation in a Power System