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Unread 05-09-2010, 23:30
Unsung FIRST Hero
Al Skierkiewicz Al Skierkiewicz is offline
Broadcast Eng/Chief Robot Inspector
AKA: Big Al WFFA 2005
FRC #0111 (WildStang)
Team Role: Engineer
 
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Re: reverse-voltage protection

Marshall,
I would be willing to bet that the majority of dead controllers due to wiring errors are for the input and output to be reversed. Remember that the HEX power FETs that are used have a diode across the source drain leads that is a fall out of the manufacturing process. The series diode would still need to handle 129 amps, the stall current of the current CIM motors. Schottky diodes have a lower forward voltage drop but are too expensive and large to be included in the controller design. We use the smaller Anderson connectors for all/most of our motor connections. The 45 amp version handles the CIM motors just fine. There is not enough heating in a two minute match to damage these connectors provided that the correct crimper is used to terminate the wire.
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Good Luck All. Learn something new, everyday!
Al
WB9UVJ
www.wildstang.org
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Storming the Tower since 1996.