Hello together,
My Multiplus 2 inverter in recently making some strange high frequency noises. For the master Multiplus inverter, with a single tap noise dissapeared, but for the slave Multiplus, won’t. I opened it up and noise seems to come from relayas or chopper, but i’m not sure. Actual load is ~ 120W, not charging batteries. Do you have any impression where sound is coming from? or similar cases?
You have there two frequencies overlaping.
The HF of inverter’s PWM over the final 50Hz result.
It’s either the main transformer or the filter in series with the main transformer’s primary winding.
I’ve checked once more and seems that noise is coming from white REL2 relay (looks like something loose inside). Once I’m pressing a bit on it, the high pitch noise is going off.