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
ken white wrote:
Unless the 2 thermistors are exactly the same, a matched set, one of them will absorb more energy than the other and very little performance gain, if any, will be achieved - my guess is the tolerance is +- 20%.
If they are matched, the thermal time constant will be reduced and twice the current will flow sooner, which defeats the whole purpose of trying to limit the inrush...
The surge limiter is sized to absorb the in-rush created by by the energy stored in the capacitor, which is equal to C times the voltage across the capacitor squared divided by 2.
The energy is in Joules, which is the specification I stated...
Yep.
"Inrush current limiters must not be
connected in parallel. If connected in parallel, the NTC thermistor with the smallest rated resistance consumes almost the entire current in the circuit and the resulting overload could destroy the component." (from Epcos)
