Frequency
The meter calculates the instantaneous frequency of the distribution-network voltage waveform using a zero
crossing technique that ensures an accurate result even if one or two incoming phases are lost.
The maximum and minimum frequency values within a billing period (page 45) are recorded by the meter.
Neutral voltage
Neutral voltage displacement will typically occur as a result of asymmetrical loads or phase faults.
The meter calculates a neutral voltage displacement value once every second using a standard residual voltage
technique (rms value of the vector sum of the phase-to-neutral voltages). When this calculated value exceeds a
pre-programmed threshold an alarm can be triggered.
The neutral displacement threshold value is programmed using the meter support tool and must represent an
actual and realistic value. If left at 0.0V (default) the meter will constantly trigger unnecessary alarms.
Neutral current
Neutral current will typically occur as a result of asymmetrical loads.
The meter calculates a neutral current value once every second using a standard homopolar current technique
(rms value of the vector sum of the phase currents). When this calculated value exceeds a pre-programmed
threshold an alarm can be triggered.
The neutral current threshold value is programmed using the meter support tool and must represent an actual
and realistic value. If left at 0.00A (default) the meter will constantly trigger unnecessary alarms.
Current reversal
The meter detects current reversal events and records the following parameters:
number of current reversals for phases 1, 2 and 3 (incremental)
the last 10 current reversals (with time stamp, reversal direction and phase number)
Each current reversal triggers a non-fatal alarm.
Absence of current
An absence of current event occurs when the meter detects there have been no metrology pulses for a period of
10 seconds.
The meter records the following parameters:
number of current absence events for phases 1, 2 and 3 (incremental) with time stamp
Excess current
The meter calculates the current value once every second for each phase. When this calculated value exceeds a
pre-programmed threshold a non-fatal alarm can be triggered.
The meter records the following parameters:
number of excess current events for phases 1, 2 and 3 (incremental) with total duration
Number of days without internal consumption
The meter records the number of days where none of the energy registers have incremented due to a lack of
metrological activity. If the recorded number of days goes over the predefined threshold, then a non-fatal alarm is
triggered.
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