Over voltage protection

I am using 12VDC switching supplies in my products. All switchings supplies available in market have input voltage range 100-240V AC.

On UPS backup, switching supply damages due to faulty over voltage generated by UPS. ( it do not happens with all UPS).

I want to protect swithching supply.

Use a MOV (Metal Oxide Varistor) which will clamp the voltage spikes.

UPS's generally have very stable outputs, any ripple or noise caused by line switching would usually be taken care of by the input filters to your switching supply. Make sure the load you present to your switching supply is greater than the minimum required at all times.

rgds