Rms Calculation - ABB SACE Emax Series Installation, Service And Maintenance Instructions

8. Protection against phase unbalance "U";
9. Protection against overtemperature "OT";
10. Protection against undervoltage "UV";
11. Protection against overvoltage "OV";
12. Protection against residual voltage "RV";
13. Protection against reverse active power "RP";
14. Underfrequency "UF";
15. Overfrequency "OF".
The PR123/P unit allows current signal processing of the neutral pole with different relationships relative to the value of the phases.
N.B.: Beyond 15.5xIn of current on the Ne, the protection is considered as being set to 100%.
A timing indication (message + "alarm" LED) is provided on the unit's display, which is activated during a protection alarm. It is disabled when
the alarm condition ceases or when the protection has been tripped. When the circuit-breaker opens, the page with the "Trip" data is displayed
(when "i Test" is pressed, or automatically in the presence of Vaux).
14.2.6.1

Rms calculation

All the protection functions do their respective processing on the basis of the real rms value of the currents and voltages (the protection G is disabled
for current values greater than 8In [where I
If the waveform has a deformation beyond the declared limit (6.3@2In), the tolerance for the calculation of the true rms value will increase. The
UV, OV, RV voltage protections always work on the basis of the true rms value of the voltages.
14.2.6.2 Mains frequency
The PR123/P unit constantly measures the frequency of the mains voltages it is connected to.
If the frequency goes out of the permitted range by ±10% in relation to the rated frequency selected (50 or 60Hz), the "warning" LED comes on
and the warning message is displayed (see par. 14.6.3).
The signal can be combined with a relay of the optional PR120/K module or with those of the PR021/K unit.
14.2.6.3 Harmonic distortion
The PR123/P unit signals that a peak factor of 2.1 has been exceeded with a warning message and the "warning" LED lighting up (remember
that the IEC 60947-2 standard annex "F" establishes that the protection unit must function regularly with a peak factor ≤ 2.1, up to 2xIn).
The signal can be combined with a relay of the PR120/K module or with those of the PR021/K unit.
14.2.6.4 Circuit-breaker state
The PR123/P unit records the state of the circuit-breaker by means of specific wiring on the circuit-breaker. In the case where the presence of
current is determined with the circuit-breaker in the "OPEN" state, a state error is signaled by a warning message being displayed (see par. 14.6)
and the "warning" LED lighting up.
The signal can be combined with a relay of the PR120/K module or with those of the PR021/K unit.
14.2.7 Measurement functions
The current measuring (ammeter) function is available on all versions of the SACE PR123/P unit.
The display shows histograms with the currents of the three phases and of the neutral on the main page. In addition, the current of the phase
under the greatest load is given in numerical form. Where applicable, the earth fault current is displayed on a separate page.
The ammeter functions both in self-powering mode and with an auxiliary supply. In the latter case or in the event of self-powering for 3-phase
currents >300A ca. or when the PR120/V module is installed and powered, ammeter and backlighting are always active. The tolerance for
the ammeter measuring chain (current sensor plus ammeter) is described in paragraph 14.2.9.16.
The PR123/P release provides a complete set of measurements:
- Currents: three phases (L1, L2, L3), neutral (Ne), earth fault
- Voltage: phase-phase, phase-neutral, residual voltage
- Instantaneous voltage values over a given time interval (data logger)
- Power: active, reactive, apparent
- Power factor
- Frequency and peak factor
- Energy: active, reactive, apparent
- Harmonics calculation: up to the fortieth harmonic (waveform and module of the harmonics displayed); up to the thirty-fifth for frequency
f=60Hz
- Maintenance: number of operations, percentage of contact wear, opening data storage.
- Data Logger: see par. 16.4
The PR123/P can provide the trend of the measurements of certain quantities over an interval P, established by the user; these include: mean
active power, maximum active power, maximum current, maximum voltage and minimum voltage. The last 24 P intervals (adjustable from 5
to 120 min) are stored in a non-volatile memory and displayed in a bar graph.
To examine the Measurement functions, see the relevant paragraphs (par. 15.1 and par. 14.5.3) for the PR120/V - MEASURING module.
14.2.8 Watchdog
The PR123/P unit provides some watchdog functions able to guarantee the proper management of relay malfunctions. These functions are as
follows:
Watchdog for presence of Auxiliary power supply with "plug" icon displayed.
Rating PLUG validity.
Watchdog for proper connection of the current sensors (CS). If it is enabled, any anomalies are indicated by a special alarm message and
the "alarm" LED coming on, and the circuit-breaker opens after 1s.
L2234
Model
L2778
≥ 0.8In], greater than 6In [where 0.5In≤ I
4
<0,8In] and greater than 4In [where I
4
Apparatus
Doc. No.
1SDH000460R0002
<0.5In]).
4
Scale
Emax
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