Sonsivri

Hi,

Is it possible to use two 240vac input 12v output smps adapter supplies in series with 400vac input
with outputs also in series to get the 24v.

Regards

The details depend on the particular converter design, but you will not be able to put the inputs in series for 400Vac.
Many AC-DC converters that are SMPS, work by rectifying line to first create a DC voltage and then a switching arrangement - the input is not just a mains transformer.

The outputs, yes but your question was for both so I believe the answer is NO.

If the supplies have isolated (floating) outputs then you can connect them both to 240 VAC as usual and connect the outputs in series to get 24 V. If you're not sure about your supplies then upload the data sheet.

@max,

No, you can't use those 230VAC input supplies with 400VAC input. Input rectifier section most probably is designed for 270VAC worst case with Rectifier rating 600VDC and capacitor with voltage rating of 400/450VDC.

Agree with @UncleBog that if the outputs are isolated you can connect the outputs in series to get 24VDC.

regards,
sam_des

There are some recommendations for serial connections of SMPS outputs. Inputs also can be connected in series if the SMPS can operate with DC input voltage. In this case should be added external rectifier and capacitive divider, almost the same as it used in the half-bridge converter and also voltage balancing circuit. I have tested this solution ten years ago to design SMPS with the 660V DC input. But later I made a different design because of some instability in operation.