question

slaute avatar image
slaute asked

Multiplus II buzzing with zero current

Hi,

I have the system described by the scheme below. The system buzzes even when almost not inverting or charging the battery like in the screenshot. The buzzing is kind of intermittent with eventual periods of about 10s quiet and then a few minutes buzzing. The load is constant (hot water reservoir heating in cheap tariff).

I understand some buzzing can happen when current is flowing, but in this example, current is consumed from the grid, and battery current is very low. Why is there buzzing in these conditions?

I'm using the 497 firmware on the Multiplus II with ESS assistant and 2.91 on Cerbo GX. The battery is one Pylontech US2000C with CAN BMS connected and DVCC set to maximum current 25A. ESS maximum inverter power to 1200W. EM112 Modbus grid meter. There is a SMA PV inverter connected to AC in, but the buzzing during the attached screenshot is at night.

88f96819-6eb0-428b-b887-63f338c661e4.jpeg

Multiplus-II
88f96819-6eb0-428b-b887-63f338c661e4.jpeg (110.4 KiB)
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

1 Answer
Rob Duthie avatar image
Rob Duthie answered ·

Hi


They can buzz due to the toroid transformer inside which can react to outside frequency coming in like hot water ripple control relays like in NZ, any sort of lines introduced signal will make the transfomer buzz no load or load, it just resonants with it. Not much you can do about it.

Regards

Rob D

NZ

2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.