ABB Relion REC615, Техническое руководство

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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#
Figure 32: Milliampere input scaled to tap changer position information
3.13.2.4 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 55: 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
3.13.2.5 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 are sampled. Each RTD sensor type has expected current based on the
sensor type. If the measured offset current deviates from the reference current
more than 20%, the sample is discarded and the output is set to invalid. The invalid
measure status deactivates as soon as the measured input signal is within the
measurement offset.
1MRS758755 C Basic functions
REC615 & RER615
Technical Manual
101