I cannot say if it is "acceptable", because I am not sure what your
particular criteria for "acceptability" is. But I can say that there is
no problem technically.
In the company I previously worked for, we designed and made telco
"rectifiers" (basically they are honking big 48V battery chargers). Each
rectifier outputted 10KH, and there were 11 of them per rack cabinet
(for a total of 110KW per cabinet). At the top of each row of cabinets
there was a pair of rather large bus bars connecting the outputs of each
cabinet in parallel. I'm not talking about a puny 400A here; average
continuous current was 10,000 A, and peak current could reach 100,000A
for a short time when clearing a fuse (in this case the batteries under
charge supplied the current peak).
The bus bars were all laminated from thinner material (1/4" thick x 6"
wide copper bars). They were peppered with obround holes (i.e. slots
with rounded ends) to make bolt alignment easier. There was no problem
at all, nor can I imagine why there should be. The only problem I can
possibly see would be if rectangular slots (with sharp corners) were
used. I could see someone complaining about this causing stress
concentration and possibly being a start for crack generation. But I
doubt that this is the problem you are referring to, since only a rank
amateur mechanical designer would use a sharp-cornered rectangular slot
for bolt clearance.
Bob Wilson
TIR Systems Ltd.
Vancouver.
-----Original Message-----
From: David Sproul [mailto:[email protected]]
Sent: June 21, 2002 2:12 AM
To: EMC-PSTC
Subject: Slotted Busbars
Dear Group,
I have a client who wishes to use open slots instead of closed holes for
the connecting bolts used in joining two 400A busbar within their
product. This decision was taken to make installation and maintenance
easier. However, their installation Manager has objected to this
without giving a reason. I have e-mailed my contacts within TUV and UL,
and after some 48 hours they have not responded.
Are there any sufficiently knowledgeable people who can tell me whether
or not this is permissible, and why.
Best regards,
David Sproul.
