Function
Function
iso685-D-P_D00170_00_M_XXDE/06.2016
12
3.1.2 Features EDS44…
• Insulation fault location in AC, 3AC and DC IT systems
(AC 24…690 V, DC 24…500 V)
• Up to 12 measuring current transformers of the W…, WR…, WS… measuring cur-
rent transformer series can be connected
• Response sensitivity insulation fault location:
EDS440 2…10 mA
EDS441 0.2…1 mA
• Response sensitivity residual current measurement:
EDS440 100 mA…10 A
EDS441 100 mA…1 A
• Communication of the components via BS bus (RS-485) or BB bus
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 and IEC 61557-9. It is universally applicable in AC, 3(N)AC, AC/DC and DC sys-
tems. AC systems may include extensive DC-supplied loads (such as rectifiers, inverters,
variable-speed drives).
3.2.2 Special characteristics of ISOMETER® iso685-S-P with front panel
The ISOMETER® iso685-D-P and iso685W-D-P are devices of the iso685 device family with
integrated display. This manual applies in full to these ISOMETER®s.
The ISOMETER® iso685-S-P and iso685W-S-P are sensor variants of the iso685 device fam-
ily without display. The only difference between these variants and the ISOMETER®s
iso685-D-P and iso685W-D-P is that they do not feature a display. The ISOMETER®s
iso685-S-P and iso685W-S-P must be used in combination with a front panel because the
devices are operated via the front panel. The operation of the front panel is equal to the
operation of the ISOMETER®s with integrated display, which is described in this manual.
Only the sensor variant (ISOMETER® iso685-S-P or
iso685W-S-P
) can be
connected to the front panel. Connection to the display variant
(ISOMETER® iso685-D-P or iso685W-D-P) is not possible.
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 de-
vices 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 evaluat-
ed by a microcontrolled measuring circuit. The measuring time depends on the selected
measurement profiles, the system leakage capacitance, the insulation resistance and
possible system-related disturbances.
The response values and other parameters are set using a commissioning wizard or via
different setup menus using the device buttons and a high-resolution graphic LC display.
The selected settings are stored in a permanent fail-safe memory. Different languages
can be selected for the setup menus and the messages indicated on the display. The de-
vice utilises a clock for storing fault messages and events in a history memory with time
and date stamp. The settings can be protected against unauthorised modifications by a
password. To ensure proper functioning of the connection monitoring, the system type
3AC, AC or DC must be set and the appropriate terminals L1/+, L2, L3/- must be
connected.
