Siemens SENTRON 3WA1 - Page 135

Description
2.7 Metering function (power metering function)
3WA1 air circuit breaker
Equipment Manual, 02/2023, 92310000002-06
133
Application package
Current
meter-
ing
ready4-
COM
PMF-I
Energy
Efficiency
PMF-II
Basic
Power
Monitor-
ing
PMF-III
Advanced
Power
Monitoring
cos φ
6
✓
--
--
--
✓
✓
Frequency f
0.5
✓
--
--
--
✓
✓
Current unbalance
2.5
✓
--
--
--
✓
✓
Voltage unbalance
1.5
✓
--
--
--
✓
✓
Total harmonic distortion
THD-I
1)
2
✓
--
--
--
--
✓
Total harmonic distortion
THD-U
1)
2
✓
--
--
--
--
✓
Harmonic I, U
1)
2
✓
--
--
--
--
✓
1)
for 2nd to 15th harmonic component ±2% and 16th to 31st harmonic component ±5%
The accuracy of the current metering of a circuit breaker without the metering function
corresponds to the accuracy class specified by the manufacturer.
The accuracies of the metering values for metering functions PMF-I to PMF-III according
to IEC 61557-12 are valid for the ETU600 electronic trip unit including the integrated
current and voltage sensors for a year after calibration following delivery from the factory
only.
In the case of metering values specified by the manufacturer, the ranges specified in
IEC 61557-12 are also valid, as are their intrinsic safety limits. The accuracy of these
metering values is not confirmed during routine testing however.
The voltage can be measured using the VTM voltage tap module in a range of 100 V up
to 120% of the rated voltage of the circuit breaker (phase-to-phase voltage).
Current and voltage unbalance are determined according to different calculation
methods:
• ANSI definition:
Ratio of the greatest difference of the phases to the mean value of the phases.
• IEC definition:
Ratio of the greatest difference of the phase to the phase with the highest load.
Note
The circuit breaker loses its certification according to IEC
61557-12 if any one of the
following components required for measurement is subsequently replac
ed: ETU600,
VTM680, VTM640, internal voltage tap or internal current sensors.
For measuring the temperature, a thermocouple is mounted on the BSS200 Breaker
Status Sensor internal module and the optional communications module. The
temperature at both points can be measured with very high accuracy. However it is very
strongly influenced by the intrinsic heating of the installed electronic components and
their ambient temperature. The available metering values can therefore be used for
comparative measurements and as an indicator for changes.