5 Feb
2009
5 Feb
'09
1:44 p.m.
On Thursday 05 February 2009, Dennis Boone wrote:
Peripherals,
on the other hand, will vary. If it's got a couple
hefty disks with it, it might draw a lot more. A couple large SMD
disks can blow a 15a breaker if you spin them all up at once.
IIRC, an RA81 disk has an inrush spec of 80 amps for a time period
measured in seconds. From measuring the start-up current of an RA82, I
don't quite believe
that, unless it's 80 amps for less than 1/2 second or
so... which it
could be. I think I measured a maximum of 30-40A off of the RA82, but
that was with a digital (clamp-on) current meter, so it's possible or
likely that it spiked higher than that.
In any case, you can have a fairly high inrush current on a fairly small
circuit breaker before it'll trip; just look at the specs for a circuit
breaker sometime. Square D for example has these in their online PDF
catalog stuff. And, this makes sense because the breaker is designed
to trip based on how much the wiring is heating up... 20A ( * 80%)
continuous load will warm up the wire a lot more than an 80A inrush for
a second or two.
Pat
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