# AC voltage at the output of SMPS

We have 230 VAC power supply in our lab.A chemical earthing is done for this power supply. I have connected a SMPS (LRS-35-12) to it. The Output of SMPS is connected to a load of maximum 2A. I have measured the smps output voltage as 12VDC and the device (load) is working and controller is sending data also. But at the same time I have turn my multi-meter at AC voltage mode and measured the SMPS output voltage,I found it as 25VAC. (I expected it to be around 0 VAC.)

So, what could be the reason of it?

• What is "chemical earthing?" – JRE Jan 7 at 11:57
• It is basically the GI earthing( Rod earthing). Only we have added salt and charcoal around the rod to improve the earth pit resistance. – Aakash Dey Jan 7 at 12:02
• 25VAC across the SMPS outputs, or between the SMPS and earth? – JRE Jan 7 at 12:10
• I am giving the details below: Voltage between Line and neutral= 228-238VAC. Voltage between Earth and neutral= 20-25 VAC. Voltage at SMPS Output= 12VDC Voltage at SMPS Output= 25VAC – Aakash Dey Jan 7 at 12:16
• So, as we have earthing so a 20-25VAC between earth and neutral is unexpected. Also it is unexpected to have 25VAC at the SMPS output. – Aakash Dey Jan 7 at 12:23