HT instruments PVCHECK - Manual (Page 41)

PVCHECK
EN - 39
6.4. MEASUREMENT OF INSULATION ON PV MODULES/STRINGS/FIELDS (M
)
6.4.1. Foreword
The purpose of this function is to measure the insulation resistance of the active
conductors of a module, string, of a whole PV field and of possible unearthed metal
masses according to the prescriptions IEC/EN62446 guideline. In general, the instrument
measures insulation in the following modes:
 FIELD mode  used for measuring insulation resistance of a PV field (photovoltaic
generator) consisting in one or more strings connected in parallel. The instrument
performs the measurement on the Positive and Negative poles of the PV field.
 TIMER mode  the instrument measures continuously (with a max duration of 300s)
on terminal “P” only, displaying the minimum resistance value obtained at the end of
the selected time. It may be used for measuring the insulation resistance of more
unearthed metal masses.
 STRING mode  used for measuring insulation only on single PV modules or strings,
automatically creating an internal short-circuit between the Positive and Negative poles,
with no need to use an external switch to short-circuit the positive and negative
terminals and measuring between this short-circuit point and the installation earthing.
6.4.2. Measuring insulation – FIELD mode
1. Position the cursor onto M
 by using the arrow keys
(
,) and confirm with ENTER. The display shows the
screen to the side:
2. Press the ENTER key, activate “Settings” and possibly
change the desired parameters (see § 5.4). The following
parameters are shown on the display:
 Ins. Test  selected test voltage (250, 500 or
1000VDC)
 Ri min  minimum limit threshold for insulation
measurement
 Mode  measuring mode: FIELD
 Vtest  real test voltages applied respectively
between the Positive pole and the Negative pole of
the field respect the earthing
 Ri (+)  insulation resistance measurement between
the Positive pole of the PV field and the earthing
 Ri (-)  insulation resistance measurement between
the Negative pole of the PV field and the earthing
 Rp  final value of the measurement obtained by the
parallel of Ri(+) e Ri(-) values which is compared with
the Ri min limit by the instrument
  key  access to the second page with the
measured values of VPN, VEP and VEN voltages
15/05/12 15:34:26
I n s . T e s t : 1 0 0 0 V
R i m i n : 1 . 0 M

M o d e : F i e l d
V t e s t - - - V - - - V
R i ( + ) - - - M

R i ( - ) - - - M

R p - - - M

Selection M
 
15/05/12 15:34:26

V P N - - - V
V E P - - - V
V E N - - - V
Selection M

3. Connect the instrument to the PV field being tested and to the main earth node of the
system shown in Fig. 10. In particular, connect the negative output pole of the PV field
to terminal N and the positive output pole of the PV field to terminal P.