GE P642, Technical Manual

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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 programmable 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 in the 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.
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.
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. As standard it is set to 80% pick-up and 60% drop-off, but you can change it to other
available thresholds if that suits your operational requirements.
P64x Chapter 15 - Digital I/O and PSL Configuration
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