Mains Monitoring / Mains Disturbance Recording - Pq - Gossen MetraWatt METRAHIT ENERGY TRMS System Multimeter Operating Instructions Manual

5.1.3 Mains Monitoring / Mains Disturbance Recording – PQ
Overview
The METRAHIT ENERGY is equipped with an operating mode for
mains disturbance recording in the PQ switch position. Input
voltage is simultaneously measured with a different measuring
circuit to this end.
• The RMS value of the applied voltage is measured and
displayed continuously. (This measurement corresponds to
DC+AC TRMS measurement, see section 5.1.2.) The
measurement is used for precise detection of overvoltages and
undervoltages.
• Additionally, the voltage is sampled at 1.2 kS/s and a half-cycle
RMS value is calculated for each half-cycle: This is used to de-
tect short overvoltages (swells) and undervoltages (dips). Mains
frequency (50 or 60 Hz) must be correctly set for this measure-
ment (see section 6.4.5).
• Momentary values acquired by means of fast sampling are used
for the detection of briefly exceeded absolute values (peaks).
• Steep voltage surges within a range of 200 V to 1000 V
relative to the momentary voltage value are additionally
acquired by a sample&hold circuit.
The measuring range can be adjusted from 6 to 600 V: With the
exception of transient detection (fixed range of 200 to 1000 V), all
disturbances can be detected in all three voltage ranges, but only
at frequencies of 0 Hz (direct voltage), 50 or 60 Hz.
GMC-I Messtechnik GmbH
Measurements: V/Hz/dB – PQ/
– MHz/% – /nS/R
– /
SL
Acquirable Mains Disturbances
The following types of disturbances are recorded:
• Undervoltage (LoVoLt) and overvoltage (HiVoLt) with start time,
duration and extreme value.
• Under and overvoltage of the half-period RMS value (dips and
swells) with start time, as well as minimum and maximum
values.
• Momentarily exceeded values with a duration of greater than
1 ms (peak) with time of occurrence and maximum value
• Steep transients with a rise time of 0.5 to 5 ms within a range of
200 to 1000 V including time of occurrence, relative voltage
value and the previous 1 ms instantaneous value
Based on the example of a 230 V, 50 Hz line voltage, the
following figure depicts acquirable disturbances in addition to the
detection of undervoltages and overvoltages:
Line Voltage
It must be noted that certain events – depending upon the
threshold voltage selected for them – often occur in combination,
for example the "LoVolt" event always occurs together with the
"diP" event, if the same threshold voltage has been selected for
both, but not the other way around.
– Temp – /m – W/Wh – A/Hz/thd
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