On Sun, 02 May 2004 13:01:25 +0000, scada wrote:


"Darren" wrote in message
...
Hi, I have sold a guy a 600w modified sine inverter, was tested before
it was sent away, he received it but he couldnt get it to work (he wants
it
for
his fridge), so he brought it back to me. I tested it and it didnt work
so
I
gave him a new one, I tested it infront of him with a 500w jigsaw,
worked fine. I got a call from him two hours later, he said he tested it
on his drill it workd fine then he put it on his 300w fridge but it
didnt work so he tried the drill again and that didnt work either. So
now he has blown
up
two inverters.
The inverter has a overload cut off so I dont see how the fridge could
blow
up the inverters, anyone have any idea?

Thanks
Darren



Start up current for a compressor is generally 5-6 times the running
current!

That is normal for a 3-phase motor. A single phase motor can be a lot
higher under some circumstances. Larger compressors often have relief
valves that take the load off during startup, but I wouldn't expect that
on a 300W fridge!

A fault on the fridge is possible. Mind you, it is also possible that the
fridge compressor actually takes a lot more than 6xFLC to get going for
some reason.

I'd be tempted to test the fridge with a suitable sample/hold ammeter to
measure the starting current before going any further. The inverter really
needs to be specified with a suitable characteristic for motor starting.

--
Cheers...
Mick
Gave up on viruses & trojans - moved to Linux... :-)
Nascom & Gemini info at http://www.nascom.info