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I am needing to add a time delay for a MPii to sync and accept grid power. The scenario is that some gated estates in South Africa require 15-20min delay before inverters are allowed to sync to the grid after a grid failure to stagger and limit power draw on the infrastructure.
I know this is possible and there are a couple of other threads out there but the instructions are not very clear on how to setup the assistants and in what order. We also use ESS and South Africa Grid code.
Thanks!
The quick answer is that it's not possible without some external components. The Multi will sync as soon as the grid is seen as 'healthy' enough.
What I had to do is to add a relay and timer to the input side of the Multi with a delay of 20 minutes. This essentially starts the timer as soon as the grid becomes available and after 20 minutes engages the relay to feed power to the Multi. The drawback is that you now have to factor in an additional 20 minutes grid outage time in your battery capacity calculation. EG. If loadshedding is 2H30 and you specified a battery size that just about covers that at X load then you now have to provision capacity for 2H50. If that is not a 'boarder line' case then it's all good and well.
I think you should be able to use the "programmable relay" and "general flag" assistants to do that.
AC IN will be ignored as soon as the grid fails. After grid recovery the timer will start and after 1200s it will stop ignoring the AC IN.
Just give it a try. For testing set the time to 60s or so.
So you may have to go with the external solution.
Hi friends,
Please not that after several days of investigation, i find a way to implement perfectly a time delay for grid synch thru general flag and relay assistant WITH ESS installed.
I confirm that ESS does not respect the delay set in the relay assistant but the "relay locker" is not affected by ESS; so you could define a delay for grid sync as follw:
To define the good delay, just change the last line: time for relay locker to remain on.
In this example, delay is set as 30 seconds.
These procedure has been tested in the case of switch inverter on/off and after grid power on/off.
So iwith this solution, no external installation is required.
