ABB RELION 670 Series Technical Manual page 1044

Section 16
Monitoring
= ×
X k X
EQUATION1407 V1 EN-US
where:
X
X
Old
X
Calculated
k
Default value for parameter
out without any filtering (that is, without any additional delay). When
0, the filtering is enabled. Appropriate value of
application. Some typical value for
Zero point clamping
In order to avoid erroneous measurements when either current or voltage signal is not present, it
is possible for the end user to set the magnitude
measurement
forced to zero automatically the measured values for power (P, Q and S) and power factor are
forced to zero as well. Since the measurement supervision functionality, included in CVMMXN, is
using these values the zero clamping will influence the subsequent supervision (observe the
possibility to do zero point clamping within measurement supervision, see section
supervision").
Compensation facility
In order to compensate for small magnitude and angular errors in the complete measurement
chain (CT error, VT error, IED input transformer errors and so on.) it is possible to perform on site
calibration of the power measurement. This is achieved by setting the complex constant which is
then internally used within the function to multiply the calculated complex apparent power S. This
constant is set as magnitude (setting parameter
(setting parameter
parameters are done in such way that they do not influence internally calculated value (complex
constant has default value 1). In this way calibration, for specific operating range (for example,
around rated power) can be done at site. However, to perform this calibration it is necessary to
have an external power meter with high accuracy class available.
Directionality
If CT grounding parameter is set as described in section
power will be measured always towards the protected object. This is shown in the following
figure 540.
1038
+ - ×
(1 k ) X
Old Calculated
is a new measured value (that is P, Q, S, V, I or PF) to be given out from the function
is the measured value given from the measurement function in previous execution cycle
is the new calculated value in the present execution cycle
is settable parameter by the end user which influence the filter properties
k is 0.00. With this value the new calculated value is immediately given
VGenZeroDb is forced to zero. When either current or voltage measurement is
PowAngComp , default value 0.0 degrees). Default values for these two
k shall be determined separately for every
k =0.14.
IGenZeroDb level for current and voltage
PowMagFact , default value 1.000) and angle
"Analog
1MRK 502 066-UUS B
(Equation 227)
k is set to value bigger than
"Measurement
inputs", active and reactive
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