daklein
New Member
- Joined
- May 8, 2020
- Messages
- 190
Anyone encountered this error, intermittently? W351 (W352) - Disconnect from external source due to external short circuit. The slave disconnected from the grid, and tried to reconnect repeatedly.
I'm using silent mode when connected to grid, off-peak based on SOC thresholds about 88-95. The main inverter FLA battery is normally kept floating full. After a cloudy day or two, the other AC coupled lithium batteries get low enough that it will connect to grid. I happened to notice being connected to the grid, while lithium batteries were not empty yet, noticed the relay clicking, then set the SOC thresholds to stay disconnected.
I'm not sure if the voltage drop is excessive from the house main grid panel, over the feed to the SI inverters, when they're charging the battery or passing through large loads to the house off-grid panels that the SIs feed. It's #6 copper about 80 feet. I've checked all the connections a few times. Some of the voltage drop is occurring before the grid panel (with the 3.7kw water heater element), and the rest is occurring on the way to the SIs. here's a system diagram. https://photos.app.goo.gl/HAmaaRnATvQqgFY39
I could check all the connections again. I have not checker breaker resistances, maybe there's one that's not so good. It's interesting that the L1 master has a little more voltage sag consistently, but the L2 slave is what tripped.
Lines in the plots:
Yellow is utility meter kW. There's a 3.7kw water heater element fed from the grid panel directly. The load that's 7-4kw 2min long, every 15min are the SIs charging the battery, dropping out of silent mode.
Red is kW load from the SI to the off-grid panels. The well pump is shown running for 2 minutes 6:29-6:31. I think the well pump turning off triggered the issue. The well is another ~100ft of #10. 30sec later, the grid water heater element turned off.
From the zoomed in plot, the L1 grid voltage drops even more. I think this is when the slave disconnected, at 6:31, and then the master is still charging the battery by itself.
I'm using silent mode when connected to grid, off-peak based on SOC thresholds about 88-95. The main inverter FLA battery is normally kept floating full. After a cloudy day or two, the other AC coupled lithium batteries get low enough that it will connect to grid. I happened to notice being connected to the grid, while lithium batteries were not empty yet, noticed the relay clicking, then set the SOC thresholds to stay disconnected.
I'm not sure if the voltage drop is excessive from the house main grid panel, over the feed to the SI inverters, when they're charging the battery or passing through large loads to the house off-grid panels that the SIs feed. It's #6 copper about 80 feet. I've checked all the connections a few times. Some of the voltage drop is occurring before the grid panel (with the 3.7kw water heater element), and the rest is occurring on the way to the SIs. here's a system diagram. https://photos.app.goo.gl/HAmaaRnATvQqgFY39
I could check all the connections again. I have not checker breaker resistances, maybe there's one that's not so good. It's interesting that the L1 master has a little more voltage sag consistently, but the L2 slave is what tripped.
Lines in the plots:
Yellow is utility meter kW. There's a 3.7kw water heater element fed from the grid panel directly. The load that's 7-4kw 2min long, every 15min are the SIs charging the battery, dropping out of silent mode.
Red is kW load from the SI to the off-grid panels. The well pump is shown running for 2 minutes 6:29-6:31. I think the well pump turning off triggered the issue. The well is another ~100ft of #10. 30sec later, the grid water heater element turned off.
From the zoomed in plot, the L1 grid voltage drops even more. I think this is when the slave disconnected, at 6:31, and then the master is still charging the battery by itself.
