Multiplus 12/3000/120-12 - firmvare 260052 VE BUS
CCGX running venus 3.52 VE BUS and VE direct
BMV-712
MPPT smart 150/35 (430v solar a 24v) VEDIRECT
MPPT smart 75/15 (200v solar at 12v) VEDIRECT
Agrofet 100A
Alternator 130A
400ah lithium batteries (local non communicating BMS)
I’m trying to have my multiplus assisting when ac1 input voltage is low.
Input is 198 v and when I turn on aircondition the multi raises the voltage to 230. When aircon is running it stops assisting - voltage drops and aircon stops
The Multiplus can only match the incoming voltage, it can not boost the incoming voltage because the ac input and output are connected in the unit. It can only boost the current flowing. If it tried to boost the voltage while connected to ac then it would export energy to the grid. Assist only works to add extra current if the Multiplus reaches the input current limit. So what is probably happening is you turn the ac on, the ac draws current from the grid, the voltage drops below the voltage cut out. What you need to do is set the ac input current limit to a low value so that your input voltage does not fall below the 185V input voltage cut out. You may find that the start up surge of the ac is still an issue.
Just for clarification I will explain my observation in the new GX interface
When aircon is not running AC in and AC out shows 197v in both places.
When turning on the aircon AC in stays at 197v but the AC out jumps to 230v and the aircon runs for some 40-50 seconds - then AC out falls back to 197 and aircon displays the code for low voltage.
What happens during the period where AC out I reading 230?
Kind regards
Lasse
| pwfarnell Victron Expert 16 August |
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The Multiplus can only match the incoming voltage, it can not boost the incoming voltage because the ac input and output are connected in the unit. It can only boost the current flowing. If it tried to boost the voltage while connected to ac then it would export energy to the grid. Assist only works to add extra current if the Multiplus reaches the input current limit. So what is probably happening is you turn the ac on, the ac draws current from the grid, the voltage drops below the voltage cut out. What you need to do is set the ac input current limit to a low value so that your input voltage does not fall below the 185V input voltage cut out. You may find that the start up surge of the ac is still an issue.
You have voltage drop in the cables to your ac hook up point which is why it is low.
The air conditioner starts up and tries to draw from the grid.
The grid voltage drops below the Multiplus low cut off value, the Multiplus disconnects the grid and swaps to inverting in island mode so it goes to the 230V target.
The AC unit completes its start up.
As the grid no longer has the AC unit power the grid voltage recovers to 198V, which is above the Multiplus cut off voltage, so the Multiplus synchronises to the grid voltage of 198V to reconnect, tripping the ac.
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