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Unread 04-04-2012, 15:48
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Al Skierkiewicz Al Skierkiewicz is offline
Broadcast Eng/Chief Robot Inspector
AKA: Big Al WFFA 2005
FRC #0111 (WildStang)
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Re: Intermittent connection on field only

The Victor FETs are rated at around 40 amps each with three in parallel for each leg of the bridge for about 120 amps. This figure is continuous with peaks above that but must be derated as junction temperature goes up. Remember that neither controller has any heatsink for the power devices. The 40 amp circuit breaker can withstand up to 240 amps for short durations but will likely first trip between 100 and 120 amps. The trip point is reduced for each successive trip as the breaker heats up internally. When the breaker trips repeatedly, it buzzes and gets HOT!
The stated trip for the Jag is greater than 90 amps for just under 1 second, with 100 amps stated as the maximum current through the device. Following an over current trip, the Jag will wait about 3.5 seconds before re-enable. While the series resistance for the FET is lower than the one used in the Jag, there are only two per leg.
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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.