Limiting initial cold PTC current

Thread Starter

danl

Joined Sep 24, 2013
60
Would like to power two 12vdc PTC heaters simultaneously.
They will be in parallel and each at about 2.5ohms cold. That would be about a 10A surge. I would like to drop that. So, would putting an NTC in series ahead of the two PTCs buffer the initial surge?
The circuit would have an "on" time of maybe 10 minutes to preheat a heat sink. That cycle would not repeat for at least 15 minutes and very infrequently....maybe 5 to ten times a week.
Expecting to see current increase as NTC heats up, reducing a surge as the PTC heaters see a slowed current application.
Thank you.
 

LowQCab

Joined Nov 6, 2012
4,026
A simpler way to implement the Circuit below is to just use
a DPDT, Center-Off, Toggle-Switch,
but that would require a fully manual start-up procedure.
.
It's also easy to add an Automatic-Delay-Timer to the Circuit below.

It can also be done fully Solid-State, instead of Relays.
.
.
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Heater Staging .png
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MisterBill2

Joined Jan 23, 2018
18,176
What is wrong with the heaters drawing more current initially?If it is within their ratings, and the power source canhandle that much current???
 
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