SW 4024 Trouble Qualifying AC with Autotransformer On
MrM1 Registered Users Posts: 475 ✭✭✭
Last year, after going to great lengths to balance my loads in my panel, I still was not have great success with the Conext SW 4024 AC Support mode. I had the chance to install an Outback Autotransformer (for free) and the results where a bit better. AC Support mode worked pretty well. Loads balanced. Example: 120v 1050 Watt Water heater element on L1. Without Autotransformer: L1 = 8.9 amps / L2 = 0 amps. With AT: L1 = 5.5 amps / L2 = 3.4 amps (just tested again today).
I also have wanted to put the AC in from grid to the SW on a timer, so that during the day I could run totally off grid and at night grid I could run the loads off the SW's AC support mode. A few days ago I installed a 120v Timer that controlled a 240v 40amp contactor. So far so good. Works as expected.
On the 2nd day the system was running off grid, and at the set time, the timer turned the AC in from grid on ... and i notice my lights flash on/off 2 or 3 times over a few seconds. I did not like that. So this morning I am checking everything.
Here is what I noticed:
- The issue is not the timer or the new contactor. Working fine. Test both with L1/L2 voltage and not with L1/L2 voltage to insure contactor was closing.
But here is the Problem. With no loads on the SW (except self consumption)
- With the Autotransformer switched OFF (it has it's own breaker), I apply Grid AC and the SW Qualifies AC in no problem in the 10 seconds as set in the SW and the physical sound of the transfer is very smooth, a single click of a contactor inside the SW. The SW's AC support mode is on, and I then turn the the water heater load on but it is not balanced at all.
- BUT when the Autotransformer is ON, And I apply Grid AC with no loads on the SW, the SW goes to 10 seconds and there is a load click inside the SW, (I assume the AC in contactor) but it is still trying to Qualify the AC. The SW waits another 10 seconds and tries again. Click, sometimes it Qualifies, sometimes the SW is still trying to Qualify. Waits another 10 seconds and tries again. AC Qualifies.
- The AC is there, I can see a reading off it in the Combox on L1 and L2 it is just not qualified. And each time the SW tries to qualify the AC it just makes a load click.
- Once the AC finally qualifies, the SW reports AC Good and everything works as expected.
I tested this 3 times today. With the Autotransformer on and no loads on the SW, Sometimes the SW Qualifies the AC the first time, sometimes the second attempt, and the last time I tried it, the SW took 3 attempts before the AC would Qualify. Each attempt with the sound of a load click coming from within the SW which I assume is the AC in Contactor as I watched and waited.
My assumption is this is hard on the SW. Why would this be happening with the Autotransformer on and no loads, but not with the AT off? I also assume if there were loads, it would be even more difficult and harder on the Contactor inside the SW.
Ideas on how to correct this. Or should I just leave the AT off if using the timer and when powering on Grid AC in? But if yes, again why is this happening (so that I can understand).
REC TwinPeak 2 285W 3S-3P 2.6kW-STC / 1.9kW-NMOT Array / MN Solar Classic 150 / 2017 Conext SW 4024 Inverter latest firmware / OB PSX-240 Autotransfomer for load balancing / Trojan L16H-AC 435Ah bank 4S connected to Inverter with 7' of 4/0 cable / 24 volt system / Grid-Assist or Backup Solar Generator System Powering 3200Whs Daily / System went Online Oct 2017 / System, Pics and Discussion
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