15. APPENDIX 2 – THEORETICAL OUTLINES
15.1 VOLTAGE ANOMALIES (VOLTAGE SAG AND SURGE; SPIKE)
The instrument records as voltage anomalies all those rms values, calculated every
11ms, beyond the percent thresholds of Voltage Reference (Vref) set during the pro-
gramming. The maximum upper limit percent is reduced as Vref approaches 1000V.
THE REFERENCE MUST BE SET TO
Nominal Voltage Phase to Neutral: for Single Phase and 4 wires three phase system
Nominal Voltage Phase to Phase: for 3 wires three phase system
Example1: Three Phase System 3 wires
Vref = 400V, LIM+= 10%, LIM-=10% =>
High Lim = 480 x (1+10/100) = 528V
Low Lim = 480 x (1-10/100) = 452V
Example2: Three Phase System 4 wires
Vref = 277V, LIM+= 5%, LIM-=5% =>
High Lim = 277 x (1+5/100) = 290.85V
Low Lim = 277 x (1-5/100) = 263.15V
The Instrument will detect Voltage Anomalies if the RMS Voltage Values (calculat-
ed every 11ms) beyond the above calculated thresholds. These limits remain
unchanged throughout the recording period.
When a Voltage Anomaly Occurs the Instrument Records:
• The number corresponding to the phase where the anomaly occurred.
• The “direction” of the anomaly: “UP” and “DN” identify respectively voltage drops
(sag) and peaks (Surge).
• The date and time of the beginning of the event in the form day, month, year, hour,
minutes, seconds, hundredths of second.
• The duration of the event, in seconds with a resolution of 11ms.
• The minimum (or maximum) value of voltage during the event.
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DM-4 Power Quality Recorder
