28
REFUsol 48K-UL
REFU Elektronik GmbH
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4.10
DC and AC Wiring Feedthrough
NOTICE
For outdoor installations, suitably rated fittings or hubs must be used
To ensure the NEMA 4 protection class, only use the DC input connectors provided
and connect them according to the connector manufacturer's mounting
instructions. Use the enclosed DC and AC small housings to connect conduit to the
inverter. To prevent any penetration of moisture and dirt, and maintain NEMA 4
protection class, use only UL listed rainproof or wet location hubs with rubber seals.
Failure to do so could void your warranty!
DC and AC Connection
Fig. 12: Small electrical housings provided for AC and DC conduit connections.
1. Drill the desired size hole in the small electrical housings provided with the inverter
2. Make sure the seal provided is used with the corresponding small electrical housings to maintain
NEMA 4 protection
3. Insert an appropriately-sized NEMA 4 conduit hub in each feedthrough opening.
4. Insert the appropriately sized wires through the hub.
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4.11
Grid Line Impedance
For better efficiency, large line cross-sections in single cables are increasingly used for power supply lines,
especially if local conditions require long supply lines.
In large-scale plants, it is recommended as a best practice to locate the inverters in close proximity to the
step-up transformer. If the inverters are located in a decentralized fashion, with long distances to the
transformer, the higher AC cable inductance can lead to increasing line impedances. This can lead to voltage
distortions and error messages with regards to:
Grid overvoltage (long cable)
Increased operating noise of the inverters (short cable)
