[sdiy] Power-One HAA15-0.8-A Power Supply Questions

[J. Larry Hendry]

I will offer an opinion on fuse protection that may be considered very
conservative by some.  But, it comes from my background working in high
voltage daily.  I think the fuse is always the first order of business when
the AC enters the cabinet.  I always put my fuse ahead of the switch in the
hot line.  Yes, if you have 2 supplies on one switch and fuse, your fuse is
effectively twice the size it needs to be.  With a fast blowing fuse in the
1-2 amp range, does that make a difference?  Maybe.  If it bothers you, use
3 fuses instead of 2.  But, the fuse ahead of the power switch is the most
important in my opinion.  If I were allowed only one fuse, that is where I
would put it.  A fuse a little large in front of the switch might make not
be perfect protection for the supply.  But, if the switch fails without a
fuse because the "perfect" fuse is in on the load side of the switch in the
line to the power supply, you are now either relying on the house breaker,
or starting some kind of fire (neither of which I recommend).

I never switch neutrals.  I don't see any reason to have both conductors in
the same switch housing.  And, certainly I would never do that unless the
hot leg is fused ahead of the switch.

Larry H

----- Original Message -----
From: Scott Stites <scottnoanh at peoplepc.com>
To: <synth-diy at dropmix.xs4all.nl>
Sent: Wednesday, April 23, 2003 12:25 AM
Subject: [sdiy] Power-One HAA15-0.8-A Power Supply Questions


Hi All,

I received a couple of the Power One HAA15-0.8-A power supplies from MPJA
today.  Before I proceed, I want to double check for safety's sake -
hopefully someone here can help.

The input and output are pretty straightforward.  Having 120 VAC AC mains, I
know to jumper terminals 1&3 together, jumper terminals 2&4 together, and
hook the AC up to terminals 1&4.  There's a note on the power supply VW1 and
VW2 need to be cut for +/-15V operation (which I plan to use), and they are
already cut, so I'm assuming it was configured for +/-15V in its previous
life.

I plan to use a three prong plug AC cord and and connect earth to the
chassis of the power supply with a lug.  I plan to eventually use both
supplies.  So, it is my intent to have one power cord going into the
cabinet, then run split hot to both supplies within the cabinet, split
neutral to both supplies, and from the same point, split ground to both
supplies.  Each hot line will have a fuse in it.  Should I place the power
switch in the hot line, or should it be DPDT for hot and neutral?   Are
there any safety flaws in the plans I've described here?

Any advice is appreciated.

Thanks,
Scott