Measuring The Insulation Resistance Of The Pv Generator - ABB UNO-DM-TL-PLUS-US Product Manual

M
easuring the insulation resistance of the PV generator.
The insulation 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
To measure the insulation resistance of the PV generator compared to
ground , the two poles of the PV generator must be short-circuited
(using a suitably sized selector).
Once the short-circuit has been made, measure the insulation resistance
(Riso) using a megohmmeter positioned between the two shorted poles
and ground (of the inverter).
MODELS - TL (without insulation transformer). If the measured insu-
lation resistance (Riso) is less than 500 MOhm, the inverter may not con-
nect to the grid because of low insulation of the PV generator to ground.
MODELS - I (with insulation transformer). If the measured insulation
resistance (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 inverter will not connect to the grid due to low insulation of the PV
generator to ground.
- 150 -
8 - Maintenance
IG
_
+
IG
_
+
Mega
Inverter