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PV-ISOTEST
EN - 18
6.2. M
– MEASUREMENT OF INSULATION ON PV MODULES/STRINGS/FIELDS
The purpose of this function is measuring the insulation resistance of the active conductors
of PV modules, strings and fields according to the prescriptions of IEC/EN62446-1 and
IECEN61557-2 guidelines,
with no need to use an external switch to short-circuit the
positive and negative terminals
.
CAUTION
The insulation measurement can be performed on a single module, on a
string or on a system consisting of several strings connected in parallel
If the module/string/system has a pole connected to ground, this connection
must be temporarily disconnected
In compliance with IEC/EN62446-1, the test voltage Vtest must be
≥
rated
voltage of the system
The
IEC/EN62446-1 g
uideline sets 1M
as the minimum insulation
resistance limit value for systems with rated voltage higher than 120V
Disconnect the string/system from the inverter and any dischargers
It is advisable to carry out the insulation measurement upstream of any
blocking diodes
In general, the instrument measures insulation in the following modes:
DUAL
mode
the instrument measures insulation in a sequence between the positive
pole (+) and the PE reference and between the negative pole (-) and the PE reference
of PV modules, strings and fields.
TMR
mode
the instrument measures continuously (with a max duration of 999s)
between terminal “N” and PE reference, displaying the minimum resistance value
obtained at the end of the selected time. In this way, the instrument also calculates the
DAR (Dielectric Absorption Ratio) and PI (Polarization Index) parameters
if the duration
of the test is adequate for the calculation of the above parameters.
6.2.1. Measuring insulation – DUAL mode
1. Position the cursor onto
M
by using the arrow keys
(
,
) and confirm with
ENTER
. The display shows the
screen to the side. By using the arrow keys (
,
) again,
select the “
DUAL
” measuring mode, in position “MODE”.
M
15/10 – 18:04
( + )
( - )
V t e s t
- - -
- - - V
R i n s
- - -
- - - M
R p
- - -
M
V P N
V P E
V N E
0 V
0 V
0 V
DUAL 1500V 1.00M
MODE
Vtest. Lim.
2. Use the arrow keys
or
and select the position
“
Vtest
” to set the test voltage.
3. Use the arrow keys (
,
) to select one of the following
test voltages (Vnom):
250, 500, 1000, 1500VDC
.
Please
note that in compliance with IEC/EN62446-1 the test
voltage Vtest must be
≥
rated voltage of the system
M
15/10 – 18:04
( + )
( - )
V t e s t
- - -
- - - V
R i n s
- - -
- - - M
R p
- - -
M
V P N
V P E
V N E
0 V
0 V
0 V
DUAL 1500V 1.00M
MODE
Vtest.
Lim.