Got a 48VDC to 120VAC (800W) pure sine wave inventer I'm using at multiple sites. The input requirements are a 25A fuse at 48vdc. I fused the input at 25A and turned the inventer on. There is NO load on the 120V output of the Inverter yet. Unit was running fine for the day and we left the site.. Now I came back and at both sites the input fuse had blown.. ??? Any ideas? Again there was no load at all on the output of the inverter. Really funny that both sites failed with no load on the AC side.

 

My guess is that those inverters expect at least some amount of load on them at all times when operating, many switching type power supplies do. With absolutely no load the output spikes can get out of hand.