Power Line Quality

[Richard Bair]

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!

 

[Richard Bair]

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

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

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.

 

[holyhigh]

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!

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

 

[tm]

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

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