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From: karn@mouton.UUCP
Newsgroups: net.space
Subject: Re: Fuses in Solar Max
Message-ID: <11@mouton.UUCP>
Date: Thu, 10-May-84 03:06:56 EDT
Article-I.D.: mouton.11
Posted: Thu May 10 03:06:56 1984
Date-Received: Sun, 13-May-84 10:25:20 EDT
References: <12249@sri-arpa.UUCP>
Organization: Bell Communications Research, Inc
Lines: 15

Fuses are common practice in spacecraft. Normally, they are sized such
that only a catastrophic failure of the associated subsystem will
blow the fuse. This prevents a failure of a (possibly replicated) subsystem
from dragging down the common power supply bus and possibly losing the
entire spacecraft.

Subsystems which could reasonably be expected to draw occasional overloads
are indeed often protected instead with resettable (by command or by timer)
"circuit breakers". But there are still many failure points in a spacecraft
which are hard to protect against without total redundancy of each
and every subsystem, which is often just not practical. You also have
to weigh the (normally high) reliability of fuses against more complex
(and hence more likely to be unreliable) auto-resetting circuit breakers.

Phil