iso685-D-P_D00170_00_M_XXDE/06.2016
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Special functions for coupled IT systems
13. Special functions for coupled IT systems
13.1 Particularities when monitoring coupled IT systems
When using ISOMETER®s in IT systems, make sure that only one active ISOMETER® is con-
nected in each interconnected system. If several ISOMETER®s are to be connected to the
IT system, ensure that only one ISOMETER® is active in the IT system via system isolation
using the digital input or Ethernet (ISOnet function).
If IT systems are interconnected via coupling switches, make sure that ISOMETER®s not
currently used are disconnected from the IT system and deactivated.
IT systems coupled via diodes or capacitances may also influence the insulation monitor-
ing process so that a central control of the different ISOMETER®s is required.
13.2 System isolation via digital input with two coupled systems
In order to deactivate the ISOMETER® via one of the digital inputs,
the cou-
pling switch must have a free contact.
If IT systems are interconnected via coupling switches, one ISOMETER® al-
ways remains inactive. Insulation fault location in the IT system of the in-
active ISOMETER® is only possible when the associated EDS are in auto
mode (see
). In addition, insulation fault
location with a portable EDS must be activated for the active ISOMETER®
(setting: Use portable EDS = on, see
“Using a portable EDS” on page 52
Via the X1 connector, the ISOMETER® can be isolated from the IT system and the measur-
ing functions can be deactivated. Therefore, the function of the digital input in use has to
be set to "Device inactive".
If the digital input used for this function is selected, the connectors L1/+, L2, L3/- are de-
activated via internal system isolating switches, the measuring function stops and the fol-
lowing message appears on the display: "Device inactive. Device separated".
Stored fault messages are reset when the cause of the fault has been eliminated (Reset
function).
If the digital input is no longer selected, first the connection to the IT system is restored
and afterwards, an entirely new measuring cycle for the insulation monitoring starts.
This function can be used to disconnect the second ISOMETER® selectively in coupled IT
systems via the auxiliary contact of the coupling switch.
IT-System 1
IT-System 2
PE
Adr.3
Adr.3
Adr.1
Adr.1
PE
I
L
I
n
ISOSCAN®
EDS440
7 6
5
3
4
2
0
1
5
3
4
2
0
1
9
TEST
MUTE
RESET
ALARM
ALARM
ON
COM
SERVICE
CHANNELS
SLAVE ADDRESS
12
11
10
9
8
7
1
2
3
4
5
6
I
∆
L
I
∆
n
I
L
I
n
ISOSCAN®
EDS440
7 6
5
3
4
2
0
1
5
3
4
2
0
1
9
TEST
MUTE
RESET
ALARM
ALARM
ON
COM
SERVICE
CHANNELS
SLAVE ADDRESS
12
11
10
9
8
7
1
2
3
4
5
6
I
∆
L
I
∆
n
