Table 339: SMAIHPAC Output signals
Name Type Description
AI3P GROUP SIGNAL Analog input 3-phase group
AI1 GROUP SIGNAL Analog input 1
AI2 GROUP SIGNAL Analog input 2
AI3 GROUP SIGNAL Analog input 3
AI4 GROUP SIGNAL Analog input 4
12.1.5 Settings
Table 340: SMAIHPAC Non group settings (basic)
Name Values (Range) Unit Step Default Description
ConnectionType Ph - Ph
Ph - N
- - Ph - N Analogue input connection type
SetFrequency 2.0 - 500.0 Hz 0.1 50.0 Desired frequency to be extracted by the
filter
FreqBandWidth 0.0 - 60.0 Hz 0.1 0.0 Extra added frequency band around the
set frequency
FilterLength 0.1 s
0.2 s
0.5 s
1.0 s
2.0 s
4.0 s
-
- 1.0 s Approximate length of the filtering window
in seconds
OverLap 0 - 95 % 5 20 Filtering window overlap between two
calculations in percent
12.1.6 Operation principle
For all four analogue input signals into this filter (i.e. three phases and the residual
quantity) the input samples from the TRM module which are coming at rate of 20
samples per fundamental system cycle are first stored. When enough samples are
available in the internal memory, the phasor values at set frequency defined by the
setting parameter SetFrequency are calculated. The following values are internally
available for each of the calculated phasors:
• Magnitude
• Phase angle
• Exact frequency of the extracted signal
Note that the special filtering algorithm is used to extract these phasors. This
algorithm is different from the standard one-cycle Digital Fourier Filter typically used
by the numerical IEDs. This filter provides extremely good accuracy of measurement
and excellent noise rejection, but at the same time it has much slower response time.
It is capable to extract phasor (i.e. magnitude, phase angle and actual frequency) of
Section 12 1MRK502052-UEN B
System protection and control
596
Technical manual
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