iso685-x-B_D00177_07_M_XXEN/07.2019
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Function
3. Function
3.1 Features
• ISOMETER® for IT AC systems with galvanically connected rectifiers or inverters and
for IT DC systems (IT = unearthed systems)
• Automatic adaptation to the existing system leakage capacitance
• Combination of
AMP
PLUS
and other profile-specific measurement methods
• Two separately adjustable response value ranges of 1 kΩ…10 MΩ
• High-resolution graphical LC display
• Connection monitoring (monitoring of the measuring lines)
• Automatic device self test
• Graphical representation of the insulation resistance over time (isoGraph)
• History memory with real-time clock (buffer for three days) for storing 1023 alarm
messages with date and time
• Current or voltage output 0(4)…20 mA, 0…400 μA, 0…10 V, 2…10 V (galvanically
separated), which is analogous to the measured insulation value of the system
• Freely programmable digital inputs and outputs
• Remote setting via the Internet or Intranet
(Webserver/Option: COMTRAXX® gateway)
• Remote diagnosis via the Internet (made available by Bender Service only)
• isoData: Continuous uninterrupted data transmission
• RS-485/BS (Bender sensor bus) for data exchange with other Bender devices via
Modbus RTU protocol
• BCOM, Modbus TCP und web server
• ISOnet: Internal separation of the ISOMETER® from the IT system
to be monitored (e.g. if several IT systems are interconnected)
• ISOnet priority: Permanent priority of a device within the network
• ISOloop: Special function for ring systems (all systems are coupled)
3.2 Product description
3.2.1 General product description
The ISOMETER® is an insulation monitoring device for IT systems in accordance with
IEC 61557-8.
It is universally applicable in AC, 3(N)AC, AC/DC and DC systems. AC systems may include
extensive DC-supplied loads (such as rectifiers, inverters, variable-speed drives).
3.2.2 Special ISOMETER® characteristics
The ISOMETER® iso685–D–x belongs to the iso685 device family and features an integrat-
ed display. This manual applies in full to this ISOMETER®.
The ISOMETER® iso685–S–x is the sensor variant from the iso685 device family. The only
difference between this variant and the ISOMETER® isoHR685-D-B is that it does not have
a display. The ISOMETER® iso685–S–P must be used in combination with a front panel
through which it is operated. The operation of the front panel is equal to the operation of
the ISOMETER® with an integrated display, which is described in this manual.
Hereafter, the ISOMETER®s with integrated display are described. This description is sim-
ilar to the combination of ISOMETER® sensor variants and the front panel FP200. The
devices to which this manual applies will be referred to as ISOMETER®s hereafter.
3.3 Function description
The insulation monitoring device continuously monitors the entire insulation resistance
of an IT system during operation and triggers an alarm when the value falls below a pre-
set response value. To obtain a measurement the device has to be connected between
the IT system (unearthed system) and the protective earth conductor (PE). A measuring
current in the μA range is superimposed onto the system which is recorded and evalu-
ated by a microprocessor-controlled measuring circuit. The measuring time is dependent
on the selected measurement profiles, the system leakage capacitance, the insulation re-
sistance and possible system-related disturbances.
The response values and other parameters are set using a commissioning wizard as well
as via different setup menus using the device buttons and a high-resolution graphical LC
display. The selected settings are stored in a permanent fail-safe memory. Different
languages can be selected for the setup menus as well as the messages indicated on the
display. The device utilises a clock for storing fault messages and events in a history
memory with time and date stamp. The settings can be password protected to prevent
unauthorised changes.
To ensure proper functioning of connection monitoring, the device requires the setting
of the system type 3AC, AC or DC and the required use of the appropriate terminals L1/+,
L2, L3/-.
Only the sensor variant (i.e. ISOMETER® iso685–S–P) can be connected to
the front panel. Connection to the display variant (i.e ISOMETER® iso685–
D–P) is not possible.
