EDS470 - Bender

Installation and wir ing
Coordination with the
insulation monitoring
device
A prerequisite for operating the EDS470 system is a central insulation monitoring
device. If an insulation fault falls below the set response value of alarm 2 of the
insulation monitoring device, this device activates the insulation fault location
system EDS470. Depending on the type of the system, either the test device
PGH471 is directly activated or the control and indicating device PRC470 is
activated. Apart from system start by means of the insulation monitoring device it
also can be started manually.
When choosing the insulation monitoring device, the condition of the entire
installation must be considered. It is highly recommendable to use a device of
the series IRDH265-4/365-4 or IR475LY. By means of this device DC, AC and
3AC systems can be monitored. Due to the AMP measuring principle, mixed
systems or systems with variable-speed drives are also safely monitored.
During insulation fault location, the insulation monitoring device is set to
internal test mode because an active measurement is not possible because of the
test current generated by the PGH471.
Depending on the device which is used, it may be sensible for the measurement
input of the insulation monitoring device on the coupling side to be
disconnected from the system for the duration of the insulation fault location.
This will avoid influencing the response sensitivity. This applies to insulation
monitoring devices with an internal DC resistance < 120 kΩ, e.g. IRDH265-3 and
IRDH365-3 with 28 kΩ.
Reason: for safety reasons, the test current of the EDS470 system is restricted to
25 mA resp. 10 mA. If the insulation monitoring device remains connected
during insulation fault location, part of the test current flows to earth via the
internal resistance of the device. Thereby the sensitivity of the system is reduced.
The degree of the influence depends on the internal DC resistance R i
of the
insulation monitoring device and the value of the insulation fault.
The use of an insulation monitoring device with an R i
of 28 kΩ in a 3AC 400 V
system has no influence on the maximum sensitivity of the system. However, if
several insulation faults occur, the measurement current which is available from
the test device will also be split up on the insulation fault monitoring device,
thus reducing the possibility of detecting several faults.
The following insulation monitoring devices are to be recommended:
Nominal A-ISOMETER Special features Decoupling
system voltage
necessary
AC ≥ 230V IRDH265/365-4 High capacitances up to 500µF, no
3AC ≥ 230V response range system interferences,
DC ≥ 110V 10…990 kΩ converters, serial interface, display
AC 24-230V IRDH265/365-3 High capacitances up to 500µF, yes
3AC 24-230V Response range system interferences,
DC 24-110V 2…200 kΩ converters, serial interface, display
AC 24-230V IR475LY Capacitances up to 20µF, no
3AC 24-230V Response range type of casing
DC 24-110V
2…200 kΩ
34
TGH 1243E/02.2000