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Displaying and Printing Events
Displaying Events
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Transient Events The recorder can detect both
positive and negative transients down to one 1 µs in
duration on either the H-N and N-G circuits. If the
voltage exceeds the transient deviation threshold for
any given half cycle, a transient event will be recorded.
A transient event can include one or more transients
occurring within the same half cycle. The event column
will display the number of transients that the recorder
was able to count.
An example of a transient event can be seen in the
Event tab shown. Event #8 shows a single transient on
the N-G circuit. The polarity for this transient was
positive, the voltage was 414 volts. The transient was
detected at a phase angle of 330 degrees.
Multiple transients can sometimes occur within a ½
cycle. For example, a large single transient followed by
several cycles of high frequency ringing.
Since there are an infinite variety of wave shapes that
can be classified as multiple transients, it is impossible
to determine the accuracy of the reported information
under these conditions.
Event #18 shows an example of a multiple transient
event. This event indicates 9 transients that were
detected starting at a phase angle of 271 degrees. The
detected polarity was negative and the voltages of the
transients were measured as 469 volts.
An important point to note about a multiple transient
event such as #18 above, is that the voltage reading in
the Extreme column will be the maximum voltage
(positive or negative) of any transients that occur more
than 100 µs apart. The degree (in the fourth column) will
be the position in the cycle of the first transient. The
angle of neutral-ground transients is referenced to the
start of the hot-neutral sine wave.
If a transient is less than 1 µs in length, the recorder will
indicate the magnitude of the transient but will be
unable to determine the polarity. In this case, the
recorder will show the sign of the transient as “+”.
Sag and Swell Events Sag and swell events are
decreases and increases in line voltage that exceed the
thresholds for at least ½ cycle. Swells can occur on the