Function
Function
isoHR685W-x-I-B_D00261_05_M_XXEN/12.2021
10
The insulation monitoring device iso685… is able to measure the insulation resistance re-
liably and precisely in all common IT systems (unearthed systems). Due to various appli-
cations, system types, operating conditions, application of variable-speed drives, high
system leakage capacitances etc., the measurement technique must be able to meet var-
ying requirements in order to ensure an optimised response time and relative uncertain-
ty. Therefore different measuring profiles can be selected with which the device can
optimally adjusted.
If the preset response value falls below the value of Alarm 1 and/or Alarm 2, the associat-
ed alarm relays switch, the LEDs ALARM 1 or ALARM 2 light and the measured value is
shown on the LC display (in case of insulation faults in DC systems, a trend graph for the
faulty conductor L+/L- is displayed). If the fault memory is activated, the fault message
will be stored. Pressing the RESET button resets the insulation fault message, provided
that the current insulation resistance displayed at the time of resetting is at least 25 %
above the actual response value.
As additional Information, the quality of the measuring signal and the time required to
update the measured value are shown on the display. A poor signal quality (1-2 bars) may
be an indication that the wrong measurement profile has been selected.
The ISOMETER® has an internal system isolating switch, which makes it possible to oper-
ate several ISOMETER®s in coupled IT systems. For this purpose, the ISOMETER®s are con-
nected via an Ethernet bus. The integrated ISOnet function ensures that only one
ISOMETER® is actively measuring at a time, while the other devices are completely isolat-
ed from the system and waiting in standby mode for measuring permission.
The ISOMETER® is able to synchronise itself with other ISOMETER®s. This makes it possible
to monitor capacitive coupled IT systems without interfering with each other.
3.4 Interfaces
• Communication protocol Modbus TCP
• Communication protocol Modbus RTU
• BCOM for communication of Bender devices via Ethernet
• BS bus for communication of Bender devices (RS-485)
• isoData for recording and managing measured values
• Integrated web server for reading out measured values and setting parameters
3.5 Self test
After switching on the supply voltage, the ISOMETER® automatically and continuously
checks all internal measuring functions, the components of the process control such as
the data and parameter memory, as well as the connections to the IT system and earth.
The self test can also be activated manually by means of the test button to check the func-
tions of the relays (depending on the configuration) or it can be selected via the "Control"
menu (refer to
„Control“
).
If the relays are checked during the self-test, they switch for 2 seconds.
The progress of the manual self test is shown on the LC display by a bar graph. Depending
on the conditions in the IT system being monitored, the self test is completed after 15...20
seconds. The device then returns to the standard mode (measurement mode) and the ac-
tual measured value will be displayed after the measuring time has expired. The display
shows the message
Initial measurement
until the first valid value is measured (refer to
„Initial measurement“
).
If a fault is detected during the self test, the respective LEDs of the device light (refer to
„Alarm messages“
). In addition, the respective message will be indicated on the display
and a previously programmed output will provide the respective signal.
√
33 %
Test successful
Test unsuccessful
Test not available
(e.g. incorrect device settings).
Test is being carried out.
Measurement
technique
Coupling
Connection
TEST
