Bender ISOSCAN W Series - Operating Principle of the EDS System

ISOSCAN® EDS440 and EDS441
Device Type EDS440-L /S EDS441-L /S EDS441-LAB EDS440-LAF
CTUB102 Type B ◊
CTAF…SET Type A ◊
Other Bender devices
Device EDS440-L EDS440-S EDS441-L EDS441-S EDS441-LAB EDS440-LAF
COM460 ! ! ! !
COM465 ! ! ! !
IOM441-S ! ! ! ! ! !
CP700 ! ! ! !
MK2430 # #
IRDH575 # #
iso685-…-p BS bus BS bus BS bus BS bus BS bus BS bus
isoMED427 ◊
PGH183 ◊ ◊
PGH185 ◊ ◊
PGH186 ◊ ◊
2.3 Operating principle of the EDS system
When an insulation monitoring device detects an insulation fault, it starts the insulation fault location.
In the event of a first insulation fault, an undefined residual current flows in IT systems, which is primarily
defined by the system leakage capacitances and the value of the insulation fault. The basic idea of insulation
fault location is therefore to generate a defined locating current I
L
that flows through the insulation fault. The
locating current is driven by the system voltage and can be located in the faulty outgoing circuit using the
measuring current transformer.
The locating current is generated by the locating current injector. It is limited in amplitude and time. The
amplitude depends on the size of the existing insulation fault and the system voltage. It is limited depending
on the settings.
The locating current flows from the locating current injector via the live lines to the insulation fault location
taking the shortest route. From there, it flows through the insulation fault and the earth conductor back to the
locating current injector. This locating current pulse is detected by the measuring current transformers on the
insulation fault path and signalled by the connected insulation fault locator.
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