Bender ISOSCAN W Series - Diagrams; Response Sensitivity Curves

ISOSCAN® EDS440 and EDS441
11 Diagrams
11.1 Response sensitivity curves
System type, system voltage, system frequency, leakage capacitance and locating current influence the
response sensitivity of the EDS system.
Locating current
The locating current level can bet set on the ISOMETER®. Owing to the system type, a reduced locating
current occurs in AC systems. In contrast to DC systems, the factor in AC systems is 0.5 and in 3AC systems,
0.67.
Therefore, for use in AC and 3AC systems, set the response value on the EDS as follows:
Locating current EDS Response value
25 mA EDS440-LAF 10 mA fixed
10 mA EDS440 < 5 mA
1 mA EDS441 < 0.5 mA
Response values and characteristic curves
The response values are displayed as a characteristic, the actual response value can be above this curve or
max. −50 % below it. The tolerances of the measuring current transformers are included. The characteristic
curves apply to the respectively indicated nominal voltage. In the event of nominal voltage deviation,
you should expect a proportional change of the response values. System voltages that change during
operation or superimposed AC currents that differ from the system frequency (e.g. via frequency inverters)
or superimposed DC currents may result in response values beyond the indicated ranges.
The following characteristic curves allow easy determination of a practical response value for the insulation
monitoring device and the EDS. Proceed as follows:
1. Select the characteristic curves (3AC, AC, DC) that match your system type.
2. From this group, select a diagram with a system voltage that comes closest to the actual voltage.
3. Determine the expected leakage capacitance C
e
of the monitored system in the ISOMETER ®. Enter this
value as a vertical line in the diagram.
4. The represented characteristic curves show the response sensitivity of the EDS system with a response
value of 2 mA, 5 mA and 10 mA set on the EDS. Values above the respective curve cannot be measured.
5. Select the middle characteristic curve for a response value of the EDS of 5 mA (factory setting for EDS440).
Mark the leakage capacitance C
e
on the characteristic curve. Read out the corresponding resistance R
e
on
the characteristic curve. The determined resistance R
e
indicates the maximum response value that may
be set on the insulation monitoring device (e.g. ISOMETER® iso685-D-P). If higher response values are set,
insulation faults are no longer reliably detected. A reliable response of the insulation monitoring device is
a prerequisite for starting the EDS system.
6. If the insulation monitoring device is to be set to a higher or lower response value, determine the
resistance R for the upper and lower characteristic curve as described in point 5. Values and characteristic
curves in the range between the upper and lower characteristic curve can be roughly estimated using the
existing characteristic curves.
7. Set the determined response values on the insulation monitoring device and on the EDS.
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