Function
Function
isoPV1685xxx_D00007_05_M_XXEN/02.2020
10
3.3.2 μSD card
The integrated μSD card is used as data logger for storing all relevant events.
The following measured values, statuses and alarms are stored during operation:
•
Insulation resistance and leakage capacitance
•
System voltage, partial voltages to earth, supply voltages
•
Temperature locating current injector (isoPV1685P only)
•
Temperature coupling L+, L–
•
Insulation fault
•
Connection faults and device errors
Following each start-up, a new log file is generated. If the current file size exceeds 10
MByte during operation, a new file is generated. The file name contains the time and date
of the creation time. The typical time that is needed until the maximum file size is reached
is approximately 2 days. Hence, a μSD card with a memory space of 2 GByte can record
data for approx. 400 days.
When the maximum data limit is reached on your card, the oldest file in each case will be
overwritten. The history memory that is also copied to the μSD card contains all alarms in
csv. format.
3.3.3 Insulation monitoring
For insulation monitoring, a pulsating AC measuring voltage is superimposed onto the IT
system. The measuring pulse consists of positive and negative rectangular impulses of
the same amplitude. The period duration depends on the system leakage capacitances in
each case and the insulation resistances of the system to be monitored.
Pulse sequence of the measuring voltage for insulation fault monitoring
An insulation fault between the IT system and earth closes the measuring circuit.
When the insulation resistance between the PV system and earth falls below the set re-
sponse values
R
an1
and
R
an2
(1 = prewarning, 2 = alarm), the associated alarm relay K1 (11,
12, 14) switches. Detected insulation faults are signalled to other bus devices via the BMS
bus and the CAN bus. In addition, the alarm LEDs Alarm 1 or Alarm 2 light up.
U
m
t
3.3.4 Insulation fault location (isoPV1685P)
For insulation fault location, a suitable locating current is superimposed onto the faulty
PV system with which EDS... insulation fault locators can locate insulation faults. The
isoPV1685P provides an internal locating current injector with
I
L
≤
DC 50 mA.
Pulse sequence of the internal locating current injector for insulation fault location
When permanently installed insulation fault locators (with master capability) such as the
EDS440 are used, control and synchronisation of the locating current injector is carried
out by one of the insulation fault locators in BMS master mode. For this purpose, the
isoPV1685P has to communicate with the insulation fault locator via the BMS bus.
3.3.5 Assignment of the alarm relays K1, K2, K3
Relay assignment
K1 switches when the value falls below the alarm response value
R
an1
(insulation resist-
ance).
K2 switches when the value falls below the alarm response value
R
an2
(insulation resist-
ance).
K3 switches in the event of a device error or a connection fault.
3.3.6 Measured value transmission to the control inputs of the inverter
All recorded measured values, operating messages and alarms are made available via the
CAN bus and the BMS bus.
During the insulation fault location process, the function of insulation re-
sistance measurement is deactivated and the coupling is disconnected
from the mains.
2 s
4 s
2 s
4 s
I
L
t