
Originally Posted by
GCE
We all complain about Municipalities with regards to the state of the electrical networks but as contractors we should be looking to work with them and not against them.
They have there challenges , some self made or assisted by politics and Eskom, probably one of the main reasons.
I think most of us know that our Electricity Departments have some fantastic and highly qualified Electrical engineers employed by the municipalities who unfortunately keep having their hands tied behind there backs and then being sent out to fight the fight.
We had an interesting meeting with one of our outlying Municipalities last week and the basic topic was to work together and help each other out in overcoming some of the challenges .
We all know that PV, Inverters and battery back up systems are being installed at speed due to load shedding .We also know that all sorts of experts have suddenly appeared in the PV market, some with very little electrical knowledge .
What a lot of people don't realize is the amount of havoc that is being caused to electrical networks with all the PV/Backup installs.
We have the famous Earth Neutral bridge argument - By installing that bridge permanently there is a knock effect for network protection.
We have the transformers being lightly loaded during the day due to PV taking the loads and the voltages on those transformers increasing due to light load and then at night the voltages decreasing when load starts coming back on.
After a bout of load shedding the return loads being experienced by Municipalities is increasing rapidly and this is a place that as contractors we can assist municipalities
The battery back up systems start recharging the batteries within 60sec of grid return and impose massive loads not experienced previously. If you look at the average house sitting with base loads no higher than 2 Kw and now they have a 5Kw battery system installed with a 5Kw recharge current , we are suddenly sitting with a 7Kw base load directly after grid return.
You start looking at 10Kw and above then the increase in sudden base load is even worse.
As contractors we could reduce the increased load when setting up inverters by restricting grid charging currents to 10Amps .On a 5Kw system this would mean a 0.5C charging current which a large majority of battery manufactures are stipulating in there warranty documents anyway and should actually be happening.
Installers are looking at the battery discharge specifications as 1C and are assuming that recharge current is also 1C , which most are capable of. Have a look at the warranty documents and you may find a different scenario.
We could also delay the return to grid by longer then the regulated 60 seconds, on some inverters.
What other ways can we as Electrical Contractors assist Electricity departments ?
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