[NSRCA-discussion] Arming device

[David]

I'm not trying to bring up a sore subject but this has been bugging me since it was up a while back. I am the senior electronics technician in the plasma physics department at the University of Wisconsin. About a third of what I do is make interlock circuits for the Madison Symmetric Torus. I know that the best way of keeping things safe is to remove the potential energy from a circuit to keep bad things from happening. The problem with depending on a circuit such as the emcotec type of disconnect or to just relying solely on the radio and ESC to keep things safe is failure modes. You can plan for all different failure types but to make it a circuit that isn't a lead brick being added to the plane there are compromises that have to be made. This leads to designing systems that may deal with only the most common types of failures. For example most common diodes and tantalum capacitors usually fail in a shorted mode, but not always. Many carbon resistors will decrease in résistance just prior to opening up. You get the idea, there are just so many possibilities and combinations that in my opinion the only real way to safe a power system is to disconnect the energy source. Ok, now I feel better that I said something. 

David