We are currently evaluating a system with hot swappable power supplies and
PCBs and here is what we have found needs to be checked:
o Earthing pin makes first and breaks last
o Primary and secondary power connectors are rated for make/break
application
o Access to hazardous voltages and energy hazards
o Capacity of paralleled outputs may exceed energy hazard limits (we
are adding PTCs on the backplane for each PCB which are also hot swappable)
Richard Woods
----------
From: Richardson, William G [SMTP:[email protected]]
Sent: Wednesday, June 20, 2001 5:50 PM
To: 'Dan Teninty'
Cc: '[email protected]'
Subject: RE: Hot Swappable Power Supplies ?
There must be a bleeder resistor (across the X caps) to make the AC
input
pins safe to touch once the supply is removed from the cabinet.
If there are exposed voltage or energy hazards with the supply
removed,
there must be a restriction such that only trained personnel are
instructed
to do this OR a tool must be used to remove the supply.
-----Original Message-----
From: Dan Teninty [mailto:[email protected]]
Sent: Wednesday, June 20, 2001 4:16 PM
To: Emc-Pstc@Majordomo. Ieee. Org
Subject: Hot Swappable Power Supplies ?
Do any of my esteemed colleagues know of any specific requirements
in 60950
(UL/CSA or EN) relating specifically to hot swappable power
supplies? A
search in the PDF version of UL/CSA 60950 reveals nothing specific
when
searching for "hot", "swap", or "power supply". A visual search of
the TOC
also reveals nothing specific.
2.6.5.4 deals with :
Parts that can be removed by an operator
Protective earthing connections shall make earlier and break later
than the
supply connections
in each of the following:
- the connector of a part that can be removed by an OPERATOR;
- a plug on a power supply cord;
- an appliance coupler.
Compliance is checked by inspection.
This is the most I could find that was related, and then it is
referring to
the AC side.
Thought I would triple check with the collective brain trust to be
sure.
Appreciate any pointers to passages that I missed.
Thanks,
Daniel E. Teninty, P.E.
Managing Partner
DTEC Associates LLC
Streamlining the Compliance Process
5406 S. Glendora Drive
Spokane, WA 99223
(509) 443-0215
(509) 443-0181 fax
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