Bender EDS440-L - 12 Diagrams; Response Sensitivity Curves

EDS44x_D00201_07_M_XXDE/06.2020
41
Diagrams
12. Diagrams
12.1 Response sensitivity curves
System type, system voltage, system frequency, leakage capacitance and locating cur-
rent influence the response sensitivity of the EDS system.
Locating current
The locating current level can bet set on the ISOMETER®. In AC systems, a
reduced locating current occurs, conditioned by the system type. In con-
trast 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
EDS44x as follows:
Locating currentEDS 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 curve, the maximum
error can be ±50 %. 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
calculate with a proportional modification 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 from 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 EDS44x. 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
desired system voltage.
3. Determine the expected leakage capacitance C
e
of the monitored system in the ISO-
METER®. Enter this value as a vertical line in the diagram.
4. The represented characteristic curves show the response sensitivity of the EDS sys-
tem with a response value of 2 mA, 5 mA and 10 mA set on the EDS. Values above
the respective curve cannot be recorded.
5. Select the middle characteristic curve for a response value of the EDS44x of 5 mA
(factory setting 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
EDS44x.