4 CONFIGURING THE OPTO-INPUTS
The number of optically isolated status inputs (opto-inputs) depends on the specific model supplied. The use of the
inputs will depend on the application, and their allocation is defined in the pr
ogrammable scheme logic (PSL). In
addition to the PSL assignment, you also need to specify the expected input voltage. Generally, all opto-inputs will
share the same input voltage range, but if different voltage ranges are being used, this device can accommodate
them.
In the OPTO CONFIG column there is a global nominal voltage setting. If all opto-inputs are going to be energised
from the same voltage range, you select the appropriate value with this setting. If you select Custom in the
setting, then the cells Opto Input 1, Opto Input 2, etc. become visible. You use these cells to set the voltage ranges
for each individual opto-input.
If you are using the recommended settings application software (MiCOM S1 Agile), the product's DC supply
monitoring function detects the DC supply voltage and provides some automation for setting for the global
nominal voltage. This feature is found by right clicking on Device, then selecting Supervise Device ® Auto-setup
of Opto Voltage. This automatic detection only works for DC inputs.
Within the OPTO CONFIG column there are also settings to control the filtering applied to the inputs, as well as the
pick-up/drop-off characteristic.
The filter control setting provides a bit string with a bit associated with all opto-inputs. Setting the bit to ‘1’ means
that a half-cycle filter is applied to the inputs. This helps to prevent incorrect operation in the event of power
system frequency interference on the wiring. Setting the field to ‘0’ removes the filter and provides for faster
operation. You should note that removing the filter reduces the AC immunity. that means it is less effective at
filtering out-of-band interference.
The Characteristic setting is a single setting that applies to all the opto-inputs. It is used to set the pick-up/drop-
off ratios of the input signals.
By default the drop-off is 60% of the maximum DC input value and the pick-up threshold is 80% of the minimum
DC input value. You can change this to other available thresholds if required. Other available thresholds are 50% -
70% and 58% - 75%.
P24xM Chapter 15 - Digital I/O and PSL Configuration
P24xM-TM-EN-2.1 295
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