How about using a current limiter like here https://sedtronic.eu/img/cms/pics/NTC/ntc.png?Hi,
eventually a relay module that makes sense. (from the schematic)
* Power supply capacitor, drive transistor (instead of useless optocouplers), control LEDs, protection diode across coil, Overvoltage protection across contacts.
This all makes sense..
sadly it has not sufficient "switch current" rating for your application.
--> Choose a relay with higher switching current specification.
Klaus
I also asked about using it at DC side. In my case 12VDC 5A(or a bit more).Hi,
eventually a relay module that makes sense. (from the schematic)
* Power supply capacitor, drive transistor (instead of useless optocouplers), control LEDs, protection diode across coil, Overvoltage protection across contacts.
This all makes sense..
sadly it has not sufficient "switch current" rating for your application.
--> Choose a relay with higher switching current specification.
Klaus
I think it´s the same problem as with AC side: The nominal current is not the problem...but the inrush current. And switching a capacitor at 12V DC means a huge current peak.I also asked about using it at DC side. In my case 12VDC 5A(or a bit more).
Thank you can you recommend a current limiter fir AC or DC side? I would be very glad since I dont know how to size it or what component to use.Hi,
A current limiter seems to be a good idea.
I think it´s the same problem as with AC side: The nominal current is not the problem...but the inrush current. And switching a capacitor at 12V DC means a huge current peak.
Klaus
Thank you can you recommend a current limiter for AC or DC side? I would be very glad since I dont know how to size it or what component to use.Hi,
A current limiter seems to be a good idea.
I think it´s the same problem as with AC side: The nominal current is not the problem...but the inrush current. And switching a capacitor at 12V DC means a huge current peak.
Klaus
Datasheet I provided already states inrush current of 60A. Why to contact them. But can you recommend a current limiter for AC or DC side? I would be very glad since I dont know how to size it or what component to use.The relay is speced at a max of 5A @ 30 VDC. I would switch the DC side
if you don't mind leaving the SMPS on all the time, which would be a sad
waste of energy.
If you do the DC side, I would assume the SMPS caps all charged, so only
transient current you need to tackle would be load caps, and their respective
sizes.
When you choose a component generally speaking always crank in some margin.
So a 10A relay module might be a better choice, in general, reliability, safety.....
Note you could always use a dual relay, and switch in and out a current limiter
if doing AC side. But not all supplies startup without a "stiff" source, eg. one without
series R. So you should contact supply manufacturer support engineering and explain
your issue to see if their supply would behave.
Regards, Dana.
I´d use the application notes provided by the limiter manufacturersThank you can you recommend a current limiter fir AC or DC side? I would be very glad since I dont know how to size it or what component to use.
Thank you can you recommend a current limiter fir AC or DC side? I would be very glad since I dont know how to size it or what component to use.
--- Updated ---
Thank you can you recommend a current limiter for AC or DC side? I would be very glad since I dont know how to size it or what component to use.
--- Updated ---
Datasheet I provided already states inrush current of 60A. Why to contact them. But can you recommend a current limiter for AC or DC side? I would be very glad since I dont know how to size it or what component to use.
In my case what can be an issue? It will be at line side of the SMPS.I'd be a little careful using a current limiter. The PS might need that big surge to 'get going'.
Cautionary tale: A coworker was testing a board with a switching regulator on it. He didn't want to supply full input voltage initially, so he slowly ramped it up. He kept blowing fuses because at low input voltage it draws more current...
It´s true that an SMPS draws more ccurrent on lower input voltage. This may become problematic with fuses, polyfuses or PTCs.I'd be a little careful using a current limiter. The PS might need that big surge to 'get going'.
All true, but my point was that limiting the inrush current might cause the PS to misbehave. I would think that the mfr. would have limited the inrush if they thought it was ok...Hi,
It´s true that an SMPS draws more ccurrent on lower input voltage. This may become problematic with fuses, polyfuses or PTCs.
But an inrush current limiter is an NTC. It gets more low ohmic with higher temperature.
Klaus
You have to contact the manufacturer of the SMPS and ask if there are are
any limitations/minimums of input current, ramp rate of input V, for it to start
up properly. If that info is not in their spec sheet/manual.
Regards, Dana.
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