• Cy Cates

To: EEs and I & E Folks: Short Quiz, What to do?


Lock-ups and failures in PLCs, VFDs, CNCs, and HMIs are all problems caused by power issues. Picture a situation where your facility is experiencing these problems. Power quality issues require a power study to determine the cause, because without data, you are merely guessing at the solution.

Now that you understand that a power study is needed, how would you conduct that study?

1. In researching the problem, you discover that the equipment in question is powered by a delta power transformer, which is typically un-grounded, and have line voltages that are especially stable.

2. You suspect harmonic noise, voltage spikes, and voltage waveform distortion are associated with the cause of the problems.

Quiz - Pick one. As you see it, there are four choices. Would you monitor/measure:

A) Line voltage for voltage imbalance, voltage spikes, and voltage harmonic noise?

B) Line current for current imbalance and current harmonics?

C) Line voltage and line current with a Volt-Ohm-Milliamp meter?

D) Phase voltage for voltage imbalance, voltage spikes, and voltage harmonic noise?

Answer with Explanation below

A) Line voltage for voltage imbalance, voltage spikes, and voltage harmonic noise?

Incorrect. Voltage imbalance and wave distortion are rarely detected in line voltages.

B) Line current for current imbalance and current harmonics?

Incorrect. Current wave distortion and harmonics are rarely detected in line current.

C) Line voltage and line current with a Volt-Ohm-Milliamp meter?

Incorrect. Measuring voltage and current will not reveal voltage distortion, nor will it show harmonics.

D) Phase voltage for voltage imbalance, voltage spikes, and voltage harmonic noise?

Correct! Even though electrical loads are phase voltage referenced, they are still powered by the line. This means that noise and distortion are always found in the phase-to-ground voltages. The nominal voltage range is +10 to -15% of the phase-to-ground voltage.

Upon choosing option D for your power study, and as would typically be expected, the test data reveals voltage imbalance, harmonic noise, and voltage spikes.

Bonus Question: Now that you’ve identified the source of your equipment lockup problems, how will you solve it?

Just like the question found in the quiz, there is only one correct answer. There exists only one product, patented, tested, and proven, to permanently solve these issues while also providing several additional benefits to your power system. This product is the Phaseback Voltage Stabilizing Ground Reference (VSGR) from Applied Energy. To learn more about how Phaseback, visit the website: www.phaseback.com, Bill Hinton with Applied Energy.

Please comment if you agree or disagree, and share if you are so inclined. Give me a call if you would like a quote on Transformers or AFPT, Arc Flash Preventing Transformers.

cy cates 832 647 4606 cycates@cycates.com

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