Quote:
Originally Posted by Richard Wallace
I am not an expert, but my team has made some tests which may shed some light. See attached summary of our set up and results for recharging a 48 cubic inch system using three FRC-legal compressors.
When recharging from ~100 to ~120 PSI, the compressor must start against load. As Mr. V pointed out above, this case is much more pertinent to actual FRC operation than the tests I reported earlier.
The initial peak surge current observed using Viair compressors is relatively short duration (<0.1 sec), but the Thomas compressor's initial peak surge current is much longer duration (~0.5 sec). Comparing the Thomas surge against typical automotive fuse curves suggests an explanation for the "conventional wisdom" Jon mentioned above. The Thomas compressor has much less margin against blowing a 20A fuse during surge, and historically that is the compressor on which our FRC "conventional wisdom" is based.
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Excelent and very useful data, thanks very much.
What people need to keep in mind is that a fuse and the type of circuit breakers that we use are thermal devices. When they reach a certain temp they will open. With a large overload it will open almost instantaneously. With a slight overload it will open but in a longer period. With intermittent medium overloads it can eventual heat to the point where it opens.
So the old Thomas compressor if it starts multiple times during a match could certainly eventually heat up the fuse to the point it opens. I'm not sure why they choose the ATM form factor instead of the ATO/ATC form factor as used for the 20/30 amp circuits on the PDP, PDB and Spike. The ATM is not that much smaller than the ATO/ATC.