Measurement of alternating
quantities
ABB Network Partner AB
1MRK 580 159-XEN
Page 7 - 21
Version 1.0-00
* please, refer to the setting table for the explanation
2 Design and measuring principle
The design of the alternating quantities measuring function follows the
design of all 500-series protection, control, and monitoring terminals that
have distributed functionality, where the decision levels are placed as
closely as possible to the process.
The measuring function uses the same input current and voltage signals as
other protection and monitoring functions within the terminals; see Fig. 4.
The number of input current and voltage transformers depends on the type
of terminal and options included. The maximum possible configuration
comprises five current and five voltage input channels.
Measured input currents and voltages are first filtered in analogue filters
and then converted to numerical information by an A/D convertor, which
operates with a sampling frequency of 2 kHz.
The numerical information on measured currents and voltages continues
over a serial link to one of the built-in digital signal processors (DSP). An
additional Fourier filter numerically filters the received information, and
the DSP calculates the corresponding RMS values for:
Dependence of reporting on different setting parameters:
EnDeadB*
EnIDeadB*
EnDeadBP*
RepInt*
Reporting of the new value
Off Off Off 0 No measured values is reported
Off On On t>0 The new measured value is reported only if the time t period expired and if, dur-
ing this time, the integrating dead-band limits were exceeded
On Off On t>0 The new measured value is reported only if the time t period has expired and if,
during this time, the amplitude dead-band limits were exceeded
On On On t>0 The new measured value is reported only if the time t period expired and if at least
one of the dead-band limits were exceeded
Off On Off 0 The new measured value is reported only when the integrated dead-band limits
are exceeded
On Off Off 0 The new measured value is reported only when the amplitude dead-band limits
were exceeded
On On Off 0 The new measured value is reported only if one of the dead-band limits was
exceeded
x x Off t>0 The new measured value is updated at least after the time t period expired. If the
dead-band supervision is additionally selected, the updating also occurs when the
corresponding dead-band limit was exceeded.
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