Hi everyone. I have 2 Axpert ( Mercer) MKS II 5 Kva inverters in parallel with a 15KWh Freedomwon LiPO4 on a standalone Solar installation, which has been running fine but every now and again the inverters have been self switching to 60 Hz output despite 50Hz being the default. I'm on firmware edition 71.80. Any ideas? I'm still waiting for a response from Mustek. Thanks , Joseph

Sounds like your EEPROMs are glitching, or the power to the EEPROMs.

I'm guessing that these are getting a bit old by now, so maybe some capacitors have dried out. Perhaps seek out the capacitor replacement section of BritishRacingGreen's Repair Journey thread.

As a point of interest, do they both switch together, or does one switch and trip out due to the different frequency?

71.80 is old; 71.86 is nearly a year less old (still almost 3 years old now). There is a slim chance it might help.

hi Coulomb,  thanks for your response. One runs as master and one as slave, they reset together, but don't trip, I only noticed as my washing machine pump wouldn't pump efficiently and my microwave was sounding a bit odd, and when I checked realised the frequency was amiss, odd that its straying from the default. I only fitted the second inverter in May last year and that came with 71.80, I had to update the older one from 71.50. It run fine until about 2 months ago, and has run 3 weeks or so in between its glitches.

in the light of what you say re age, i'll double check to make sure the newer one is set as master, if the older one was and glitched it would rest the newer one to the wrong setting