I want to use a Meanwell PCB mounted power supply on my next project.


The spec sheet says that it has an inrush current of 20A/115VAC (I'm in the US so this is these are the numbers applicable to me).

Now, the device seems to have a great deal of protection, however, it doesn't say anything about a thermal shutoff; rather just that the device output is derated.

I wanted to incorporate a re-settable thermal fuse like: https://www.digikey.com/product-detail/en/F20A070053600060/317-1321-ND/1287335/?itemSeq=305616349

Such that the fuse is in series with the LINE/HOT side of the AC input to the PSU.

The thermostat is rated at 1.6A/250VAC. Under normal operation, the PSU is only drawing 0.6A/115VAC so this thermostat should be more than enough. However I am worried about the in-rush current blowing it. Should I be? If so, how would I go about mitigating it? I have read that an NTC is the way to go to limit in-rush current.

I'm not a professional electrical engineer, just a hobbyist so please keep that in mind when answering.

  • \$\begingroup\$ It wont hurt, but may not prevent abusive damage. or rapid cycling of thermal relay. It can handle it's own inrush \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Oct 6 '19 at 20:24
  • \$\begingroup\$ @SunnyskyguyEE75 could you point me to the section of the datasheet that shows that? \$\endgroup\$ – Alex Oct 8 '19 at 0:12
  • \$\begingroup\$ I dont know what conditions might cause overheating before overcurrent protection but if the thermal fuse cuts out and cycles on/off , then you get a relaxation oscillation of possible fault condition. It may be ok too. Or redundant. \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Oct 8 '19 at 5:34

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