Installation | Grid Line Impedance
Doc. No. 982056, Version 01, SelectSun 40K
|
27
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)
To avoid these disadvantageous conditions, twisted lines should be used for power supply if possible. If
laying of twisted lines is not possible, the following requirements must be met for single cores:
•
Lay single cores next to each other.
•
It is not allowed to lay single cores in closed, magnetically conducting materials (e.g., sheet steel
pipe).
•
If laid in open cable ducts, single cores should be laid such that the spacings between them are as
small as possible.
4.12 DC Connection of the Solar Generator
DANGER
Danger to life due to high voltages from active PV strings
Before connecting the PV strings, connect the inverter to the power supply
and additional ground connection.
The connection of the PV strings must always be carried out de-energized.
Note:
To avoid unnecessary loss of energy yield, the sum total of the resistive and
inductive voltage drop on the power supply line at nominal load should not
exceed 1 % of the line voltage.
Minimum spacing
between single cores!
