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000043EG
8 - Maintenance
M
easuring the isolation resistance of the PV generator.
To measure the isolation resistance of the PV generator compared to
ground , the two poles of the PV generator must be short-circuited
(using a suitably sized selector).
+
_
IG
Once the short-circuit has been made, measure the isolation resistance
(Riso) using a megohmmeter positioned between the two shorted poles
and ground (of the inverter).
Mega
Inverter
IG
+
_
MODELS - TL (without isolation transformer).
If the measured isola-
tion resistance (Riso) is less than 500 MOhm, the inverter may not con-
nect to the grid because of low isolation of the PV generator to ground.
MODELS - I (with isolation transformer).
If the measured isolation re-
sistance (Riso with floating input poles compared to ground or QF=1 with
grounding of one of the two inlet poles) is lower than 0.2 MOhm, the in-
verter will not connect to the grid due to low isolation of the PV generator
to ground.
The isolation resistance can be affected by the environmental conditions the PV generator is
in (E.g.: PV modules wet from damp or rain), and therefore the measurement must be made
immediately after the anomaly is detected
