Data
71
TGH1394en/05.2007
8.4 Response sensitivity characteristics
The type of distribution system, system voltage, system frequency, leak-
age capacitance and test current all affect the EDS system's response
sensitivity.
The value of the test current can be set at the IRDH575 in-
sulation monitoring device and at the PGH... insulation
fault test device. Resulting from the type of supply system,
the real test current in AC systems is lower than the set-
ting. The reduction factor is 0.5 in AC systems and 0.67 in
3AC systems.
For application in AC and 3AC systems, the response
value at the EDS... has to be set as follows:
Test current EDS response value
10 mA EDS460/490 < 5 mA
1 mA EDS461/491 < 0.5 mA
For setting the response value refer to "Settings menu 2:
Channel" on page 49.
The response values are displayed as characteristic
curves. The maximum deviation can be +/- 30 %,includ-
ing the tolerances of the measuring current transformers.
The characteristic curves apply to the respective nominal
voltage indicated in the diagram. If the nominal voltage
of the system being monitored is different from the nom-
inal voltage shown in the diagram, the response values
may change proportionally. Nominal voltages changing
dynamically during operation or in case of superimposed
alternating currents that deviate from the system fre-
quency (e.g. caused by frequency converters) or superim-
posed direct currents may result in response values that
are outside the range displayed in the diagram.
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