26
26
SME2-IS - Manual - 06 - 2021
FUNCTIONAL CHARACTERISTICS
• The relay, connected as RGDAT, measures the currents (I
4
, I
8
/I
O
, I
12
) and phase voltages (U
4
, U
8
, U
12
)
and calculates the homopolar current and voltage [I
O
(if connected I
8
)
and V
O
] and the phase-to-
phase voltages U
L4-8
, U
L8-12
, U
L12-4
The input circuits are rated to handle the currents and voltages which occur in case of permanent
regime fault.
Measured signal processing
The system offers a variety of levels of processing:
• Acquisition (base level).
• Direct measurement of physical signals (rst level).
• Calculated measurements (second level).
The measurements processed at a given level are based on the data processed in the previous level.
Each level allocates the necessary resources in terms of relative processing priority (conditioning
and conversion circuits).
ACQUISITION (base level).
The following values are sampled from the conditioned input signals:
- i
L1
...i
L3
instantaneous phase currents
- u
L1
...u
L3
instantaneous phase voltages
The relay derives a set of measurements from the above sampled input values, which are variously
used for the protection/monitoring/command functions, for displaying values on the screen or via the
serial ports, and for the DFR function.
The values processed by the relay, starting from the sampled input values, are classied as follows:
• Direct
• Calculated
• Phase
• Sequences
• Power
• Harmonics
• Averages
Direct
The instantaneous values of the input signals are processed using a DFT (Discrete Fourier Trans-
form) to calculate the amplitude and phase of the fundamental component of:
• the phase currents I
L1
,
I
L2
,
I
L3
• the phase voltages U
L1
,
U
L2
,
U
L3
acquisizione.ai
ACQUISITION
INSTANTANEOUS VALUES
≈
Active/passive sensors
IL1.ai
(I
n
)
ACQUISITION
i
L1
, i
L2
, i
L3
DFT
≈
I
L1
, I
L2
, I
L3
Active/passive sensors
u
L1
, u
L2
, u
L3
DFT
≈
U
L1
, U
L2
, U
L3
(E
n
)
ACQUISITION
Active/passive sensors
To Next Page
Loading...
Need help?
General
