M - Measurement Of Insulation On Pv Modules/Strings/Fields; Measuring Insulation - Dual Mode - HT PV-ISOTEST User Manual

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.

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
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
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".
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.
note that in compliance with IEC/EN62446-1 the test
voltage Vtest must be ≥ rated voltage of the system
IEC/EN62446-1 guideline sets 1M as the minimum insulation
CAUTION
Please
EN - 18
PV-ISOTEST
if the duration
M 15/10 – 18:04
( + )
V t e s t - - - - - -
R i n s - - - - - -
R p - - -
V P N V P E
0 V 0 V
DUAL 1500V 1.00M
MODE Vtest. Lim.
M 15/10 – 18:04
( + )
V t e s t - - - - - -
R i n s - - - - - -
R p - - -
V P N V P E
0 V 0 V
DUAL 1500V 1.00M
MODE Vtest. Lim.
( - )
V
M 
M 
V N E
0 V
( - )
V
M 
M 
V N E
0 V