AS/NZS 4777.1 [1] specifies the electrical and general safety installation requirements for inverter energy systems (IES) up to or equal to 200kVA, which injects electric power into an electrical installation connected to the grid at low voltage. The standard also covers guidelines for voltage rise due to power injections from power inverters. In clause 3.3.3, it is stated that the voltage rise from the point of supply to inverter a.c. terminals must not exceed 2% of the nominal voltage from the grid's point of supply.
Voltage Rise reports are often required to comply with utility requirements and approvals. Parallel inverters are sometimes installed in a facility. Calculating the voltage rise for each inverter might be tedious in these cases. How do we create a voltage rise report when there are parallel inverters?
Answer: Create a Voltage Rise Report using the inverter that is the furthest from the point of supply (i.e. longest cable run)
As we will show you next, this can be done using ELEK Cable Pro Web like a regular Voltage Rise Report.
Example - Installation of three (3) Parallel Inverters
Consider an installation where a Consumer Mains is connected to three (3) parallel inverters with the same ratings but differing cable lengths (40 m, 50 m, and 60 m). The cable sizing calculation must be performed for each of the circuit's sections. For this example, we have the Consumer Mains, and the three (3) Final Subcircuits are the cables connected to the a.c. Terminals of the three inverters.
When exporting a Voltage Rise Report, select the appropriate cable sizing calculation for each section of the circuit run. In this example, there is only a service main (Consumer Mains) and a final subcircuit. The final subcircuit with the longest cable length must be selected since this will calculate the installation's highest voltage rise (worst-case scenario).
Once you export the report, you will get the PDF output. Since you have selected the inverter with the longest cable run, the Voltage Rise report will show the worst voltage rise the installation will experience.
References:
[1] AS/NZS 4777.1:2016 - Grid connection of energy systems via inverters, Part 1: Installation requirements
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