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
BFL13 wrote:
I have watched this and it is over my head, but it seems from previous posts by you experts that it might be possible to go through these steps for my converter. In fact some or all of it has already been posted maybe, but I am not able to pull it together.
http://dkc1.digikey.com/us/en/tod/Ametherm/NTC/NTC.html
We do know that the converter can do 103 DC amps at 15.5v DC output with 120v input (I have been using 15.2v setting on the voltage pot lately in the cold ambient temp 32F as being roughly equivalent to 14.8v at 80F)
It has 2400 uF capacitors (two 1,200- 250v).
So is there enough there to go through the linked steps for a recommended thermistor? If so would appreciate seeing the results posted, even if different people come up with different results it might get us (or at least me! ) somewhere closer to a correct answer.
Then we can compare that with the real answer next week when PowerMax gets back.
Thanks
BFL:
You've got lots of good info, but unfortunetly, not a complete set of the info needed. I wish it was that easy, however without a set of schematics and part list of the power supply trying to determine the proper value even range of values for thermistor is a crapshoot.
what is not known are what diodes are in the bridge, what if any inductors are in the input circuitry, what other protection may exist, what the specs on the power switch is, what output protection ciruitry exists, and if there is any other input protection circuitry.
If you have any numbers from the diodes and/or any inductors or transformers that would also help set a few more boundary conditions.
The input protection circuit must insure that all these devices are operated in their safe operating area during power up, during steady state, and during any output overloads that may occur. The thermistor may be expected to provide ALL the protection, or part of the protection. But without schematics hard to tell what it needs to do.
Also the schematics might also help determine what if any role the thermistor plays in satisfying UL and CSA safety requirements for input fault protection for safety certification. And it is highly likely it plays a role in UL/CSA certification.
