ABB Relion 630 Series, Technical Manual

Page: 103 / 380

u
1
x
2
x
1
u
1
x
2
x
1
ADx
Controller ADx_High
ADx_Low
ADx
IEC05000296-3-en.vsd
IEC05000296 V3 EN
Figure 51: 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. 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 is 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 is
informed and an alarm is given for A/D converter failure.
The ADx_Controller also supervise other parts of the A/D converter.
3.15.5 Application
The protection and control IEDs have many functions included. Self supervision with
internal event list (SELFSUPEVLST) and internal error signals (INTERRSIG)
function provides supervision of the IED. The fault signals make it easier to analyze
and locate a fault.
Both hardware and software supervision is included and possible faults can be
indicated through a hardware contact on the power supply module and/or through the
software communication.
1MRS757256 F
Section 3
Basic functions
PML630/Compact Load-Shedding Solution 97
Technical Manual