8.1.2 Measurement functionality
The functions can be enabled or disabled with the Operation setting. The
corresponding parameter values are "On" and "Off".
Some of the measurement functions operate on two alternative measurement
modes: "DFT" and "RMS". The measurement mode is selected with the X
Measurement mode setting. Depending on the measuring function if the
measurement mode cannot be selected, the measuring mode is "DFT".
Demand value calculation
The demand values are calculated separately for each measurement function and
per phase when applicable. The available measurement modes are "Linear" and
"Logarithmic". The "Logarithmic" measurement mode is only effective for phase
current and residual current demand value calculations. The demand value
calculation mode is selected with the setting parameter Configuration/
Measurements/A demand Av mode. The time interval for all demand value
calculations is selected with the setting parameter Configuration/Measurements/
Demand interval.
If the Demand interval setting is set to "15 minutes", for example, the demand
values are updated every quarter of an hour. The demand time interval is
synchronized to the real-time clock of the IED. When the demand time interval or
calculation mode is changed, it initializes the demand value calculation. For the
very first demand value calculation interval, the values are stated as invalid until
the first refresh is available.
The "Linear" calculation mode uses the periodic sliding average calculation of the
measured signal over the demand time interval. A new demand value is obtained
once in a minute, indicating the analog signal demand over the demand time
interval proceeding the update time. The actual rolling demand values are stored in
the memory until the value is updated at the end of the next time interval.
The "Logarithmic" calculation mode uses the periodic calculation using a log10
function over the demand time interval to replicate thermal demand ammeters. The
logarithmic demand calculates a snapshot of the analog signal every 1/15 x demand
time interval.
Each measurement function has its own recorded data values. In IED, these are
found in Monitoring/Recorded data/Measurements. In the technical manual
these are listed in the monitored data section of each measurement function. These
values are periodically updated with the maximum and minimum demand values.
The time stamps are provided for both values.
Value reporting
The measurement functions are capable of reporting new values for network
control center (SCADA system) based on the following functions:
Section 8 1YHT530004D05 D
Measurement functions
626 615 series
Technical Manual
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