Operation Manual

MI 2092 Power Harmonics Analyser Section VI Theory of operation

4. Voltage anomaly recording

Voltage anomalies occur when a voltage exceeds preset boundaries. The rms voltages

of each half input cycle are used for comparison. For every Voltage Anomaly detected,

the Instrument stores:

· Date & time when the anomaly started.

· The nominal voltage.

· Minimum or maximum voltage during the anomaly.

· The previous 64 rms values, calculated on half input cycles (half periods),

before the anomaly occurred.

Voltage Anomaly recording is enabled on selected voltage inputs and can be calculated

based either on a fixed tolerance window or on a variable tolerance window.

In Fixed Tolerance Mode, the nominal voltage is set by user and the high and

low limits are set as a percentage of nominal voltage.

In Variable Tolerance Mode, the nominal voltage is calculated and is the average

voltage during the previous anomaly integration period (settable between 1 and

900 seconds). The new nominal reference voltage can be up to ± 30% of

programmed nominal voltage. High and low limits are set as a percentage of

the nominal voltage and can be between ± 1% and ± 30% of the nominal

voltage.

fig 43

fig 44