Ive noticed a strange increasing and decreasing hum on my Victron Multiplus 2 GX when the washing machine is on a wash cycle.
The reason why I find this odd is the inverters grid supply isnt attached to the same ring main or supply line.
The washing machine is on the kitchen ring main, totally separate to the upstairs and downstairs socket ring mains.
Each time the washing machine does a slow roll, the hum gets more pronounced and then fades to a normal hum when the washing machine rolls stops its rolling back and forth cycles.
Is this an indication of a very weak DNO grid supply to the house, or dirty AC?
My indicated frequency always fluctuates between 49.9 and 50.2 ish Hz… But only the washing machine makes it hum louder.
Probably. I’ve heard that Torroidal transformers produced significantly more hum when the input waveform is distorted, or has a dc content. Possibly the “slow roll” has some asymmetry to the load waveform presented to the mains, and the common impedance of the subscriber drop (incoming resistance) passes the distortion to the MP.
Thank you so much for your response and info. Much appreciated!
As said, the hum isnt massive, but significant enough to be interested.
Its strange because if I put the kettle on, there’s no additional hum, but only the washing machine does it. I have done a few AI googles and there is a lot pointing to modern inverter VSD motors in washing machines kicking out a DC pulse or some sort of reflection that causes inverter power supplies to read it and react to it… But I forgot to mention that my setup is purely a storage system with the UPS function supporting a small amount of essential systems (CCTV, Heating, lights and Low load upstairs sockets) - so the washing machine isnt pulling load from the inverter and is on a completely separate ring main.
Kettle is a resistive load, so no asymmetric component. Motor speed reducers for washing machines are cheap - often can introduce dirty waveforms with some DC - hence the hum…