Power Line Quality

Dec 10, 2011 5 Replies
R

I have some questions regarding how to test/determine the minimum power line quality required for a design that has two inductive loads.



BACKGROUND: ===========



- 115V 20A rated



- Device will introduce two inductive load starts at 3-10min apart. Thus, when the second inductive load starts there is already ~7-8A steady state on the line.



- Each device can have a peak inrush of up to 80A (motor starting)



QUESTIONS: ==========



- How can I verify the worst case power line conditions required for this product? What I mean is...I believe NEC will state there can't be more than a 3% voltage drop. Is that only for steady state?



- What about the peaks a line can provide? I suspect many lines at typical distances/impedances will start to current limit and voltage will sag with



80A of inrush current.

Thanks!


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R

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This type of question has come up on the IEEE sponsored EMC group: The answers you get will apply nationally, and internationally.

=3D =3D =3D the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to

All emc-pstc postings are archived and searchable on the web at

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Graphics (in well-used formats), large files, etc. can be posted to that URL.

Website:

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List rules:
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=3D =3D =3D

Can you post there? or have someone forward your email question for you?

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R

I have sent an email to that address. I don't know what the rules are for it to be properly moderated but I will also search the web archive you mention above. Thank you.

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L

ine

Close to my pool pump, at 16A.

on

than

Probably steady state average.

ical

h

I sampled the power line when the pump was running. It looks more like saw tooth than sine wave.

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H

race condition between duration of inrush current and circuit breaker, check circuit breaker characteristics, thy can to 10X for a short lenght of time.

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T

There are breakers designed for motor starting loads. Look for HMI type. Stands for "high magnetic".

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