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Chapter 6. Description of Operation of Protection Subsystem
6-33
M7IRDA2003I
7IRD-A/J/M: Distribution Protection & Control Terminal
© ZIV APLICACIONES Y TECNOLOGÍA, S.L.U. 2020
6.13 Metering History Log
This function records periodic values of the current. The terminal samples all three phase
currents every second and then calculates an average value for each phase over the interval
defined as the Averaging Calculation Time Interval. This time interval is adjustable from 1 to 15
minutes. At the end of the interval the phase with the highest value is retained.
At the end of the recording period, called the Data Record Interval, which is adjustable between
1 minute and 24 hours, the maximum value retained from each Averaging Calculation Time
Interval is entered in the Current History Record.
TM :
Averaging
Calculation
Time
Interval; the
figure shows
the value of
TM to be
equal to one
minute.
TR : Data
Recording
Interval; the
figure shows
TR to have
a value of
15 minutes.
Figure 6.14 Metering History Log Diagram.
In each
TM window, there are two VM values that correspond to the maximum and minimum
averages, considering the three phases. In each TR interval, the maximum and minimum values
of all the computed VM values are taken. The outline of current in preceding figure would give
the following record of values: VR1-Vr1-F1, VR2-Vr2-F2, VR3-Vr3-F3, VR4-Vr4-F4 and VR5-
Vr5-F5.
Note: if during the sample interval, metering units pick up, the recorded value is the average of the measures
taken during the time in which the units have not been picked up. On the contrary, if the units remain picked up
during all the interval, the recorded value is: 0A.
The available memory for the History Record is the typical RAM, with a capacity corresponding
to 168 values (equivalent to 7 days in intervals of 1 hour). With the goal of adapting the memory
use to the application of every user, the
Days of the Week and Hours Trip can be enabled
within the defined days (the same interval schedule for all days) in addition to those that do not
register a value.
Access to the information about the Current History Record is available through the following
sequence:
Information - Records - Current History . This is explained in Chapter 8,
Alphanumeric Keyboard and Display. If the IED has Oscillographic Register; this information
only will be available through communications.