ABB RELION Series - Measurement Chain Supervision; Self-Supervision

The input scaling can be bypassed by selecting Value unit = "Ohm"
when Input mode = "Resistance" is used and by selecting Value unit =
"Ampere" when Input mode = "0...20 mA" is used.
Example for linear scaling
Milliampere input is used as tap changer position information. The sensor information
is from 4 mA to 20 mA that is equivalent to the tap changer position from -36 to 36,
respectively.
Input maximum
Input minimum
Input mode
”0..20mA”
4 mA
20 mA
Value minimum
-36
AI_VAL#
Value maximum
36
Value unit
”Dimensionless”
X130-Input#
GUID-85338A5E-3D2F-4031-A598-EA8A525190D3 V1 EN
Figure 33: Milliampere input scaled to tap changer position information
3.12.2.4 Measurement chain supervision
Each input contains a functionality to monitor the input measurement chain. The
circuitry monitors the RTD channels continuously and reports a circuitry break of any
enabled input channel. If the measured input value is outside the limits, minimum/
maximum value is shown in the corresponding output. The quality of the
corresponding output is set accordingly to indicate misbehavior in the RTD/mA input.
Table 36: Function identification, limits for the RTD/mA inputs
Input
Limit value
RTD temperature, high > 200 °C
RTD temperature, low < -40 °C
mA current, high > 23 mA
Resistance, high > 2000 Ω
3.12.2.5 Self-supervision
Each input sample is validated before it is fed into the filter algorithm. The samples are
validated by measuring an internally set reference current immediately after the inputs
1MRS758755 A Section 3
Basic functions
REC615 and RER615 89
Technical Manual