EN
76
8.6 Measuring the isolation resistance of the
PV generator
WARNING –
B
The operator must always use the personal
protective equipment (PPE) required by the laws of the
country of destination and whatever is provided by their
employer.
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 suitable sized switch).
WARNING –
B
Use of unappropriate sized switch could
cause risk of fire or electric arc! Use only 1500V rated switch!
+
_
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
+
_
If the measured isolation resistance (Riso) is less than 50kΩ, the
inverter may not connect to the grid because of low isolation of the
PV generator to ground.
ATTENTION –
A
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.
