ABB REC650 ANSI, Technical Manual

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ADx
Controller ADx_High
ADx_Low
ADx
IEC05000296-3-en.vsd
IEC05000296 V3 EN
Figure 265: Simplified drawing of A/D converter for the IED.
The technique to split the analog input signal into two A/D converter(s) with different
amplification makes it possible to supervise the A/D converters under normal conditions
where the signals from the two A/D converters should be identical. An alarm is given if the
signals are out of the boundaries. Another benefit is that it improves the dynamic
performance of the A/D conversion.
The self-supervision of the A/D conversion is controlled by the ADx_Controller function.
One of the tasks for the controller is to perform a validation of the input signals. The
ADx_Controller function is included in all IEDs equipped with an analog input module.
This is done in a validation filter which has mainly two objects: First is the validation part
that checks that the A/D conversion seems to work as expected. Secondly, the filter
chooses which of the two signals that shall be sent to the CPU, that is the signal that has
the most suitable signal level, the
ADx_LO or the 16 times higher ADx_HI .
When the signal is within measurable limits on both channels, a direct comparison of the
two A/D converter channels can be performed. If the validation fails, the CPU will be
informed and an alarm will be given for A/D converter failure.
The ADx_Controller also supervise other parts of the A/D converter.
15.1.5 Technical data
Table 490: Self supervision with internal event list
Data Value
Recording manner Continuous, event controlled
List size 40 events, first in-first out
1MRK 511 287-UUS A
Section 15
Basic IED functions
589
Technical manual