Converter In-Rush Thermistors etc, UPDATE -4
UPDATE on 17 Nov, Update 2 on 22 Nov, Update 3 on 16 Jan 14, Update 4 on 19 Oct 14. --------------- In a recent thread there was mention of how you can wreck your gizmo (in my case a converter) ...
Forum Discussion
Salvo wrote:
It appears the part is failing at start-up. The part is exploding! I don't see any advantage going in series. I think you want to keep the resistance as low as possible. I've shown you only need 0.6 ohm.
The lower the resistance, the higher the current. Power dissipated is I**2R, so initially the power dissipated increases with decreased resistance. A higher resistance will slow down the process - spreading out the energy dissipated over time. A series connection will increase the resistance and each device will only carry half the load.
That said, I'm inclined to agree that 2 ohms is OK, but in general, when specifying an NTC thermistor, you calculate a minimum resistance, then choose one that has more resistance than that minimum. It's seldom that you have to worry about a resistance that's too high, and if you do, it's not because the thermistor will fail, it's because of timing issues - the capacitors don't charge quickly enough.
If it's blowing up on startup, decreasing the resistance isn't the direction to go.
