Transducer Supervision; Signal Filtering - ABB REF 54 Series Technical Reference Manual, General

REF 54_
5.1.9.3.
5.1.9.4.
54
Feeder Terminal
Technical Reference Manual, General

Transducer supervision

The measuring signal level of each transducer is constantly supervised. If the
measured signal falls more than 4% below or rises more than 4% over the specified
input signal range of a particular channel, the transducer or the transducer wiring is
considered to be faulty and the channel-specific invalid signal is immediately
activated. The invalid signal is deactivated as soon as the transducer signal is within
the valid range.
When necessary, the valid measuring range may be narrower than the default
-4...104% of the selected measuring range. A narrower range can be defined by
means of the parameters "Input high limit" and "Input low limit" that can be found
in the menu Configuration/RTD1/Input #.
Parameter
Input low limit
Input high limit
When an input is configured for resistance or temperature measurement, the internal
excitation current generator forces a current pulse through the measuring circuit
when the input is sampled. If the actual current level does not match the programmed
level due to too high impedance in the circuit, the invalid signal is immediately
activated. The invalid signal is deactivated as soon as the circuit resistance is low
enough.

Signal filtering

Short disturbances on an input are eliminated by signal filtering. The filter time,
which defines the step response time, is set for each transducer input of the feeder
terminal by the "Filter time" parameters in the menu Configuration/RTD1/
Input #. The filtering algorithm is a so-called median filter which shows no
reaction to interference spikes but levels out directly on permanent changes.
Parameter Values
Filter time 0 = 0.4 s
1 = 1 s
2 = 2 s
3 = 3 s
4 = 4 s
5 = 5 s
Values Default
-4...104% -4%
-4...104% 104%
Default
5 s
1MRS750527-MUM