20
5.1.2.5 Alarm
configuration
The Instrument is equipped with two alarms that are triggered by a programmable threshold on anyone of
the measured parameters.
The types of alarm available are: maximum, minimum and 1-of-3.
A minimum alarm is triggered when the selected parameter is lower than the alarm threshold.
A maximum alarm is triggered when the selected parameter exceeds the alarm threshold.
A 1-of-3 alarm is triggered when anyone of the phase readings, whichever the phase involved, trespasses
the alarm threshold – this alarm can be either maximum or minimum. On a 1-of-3 current alarm, the
threshold is expressed as percentage (rather than a value) that stands for the unbalance between the
phases. The alarm therefore triggers when the percent difference between two of the three phases exceeds
the threshold; it is calculated as 100 x (I
max
– I
min
)/I
max
.
All alarms allow also the setting of an hysteresys and a delay time.
The
hysteresys
(in percent) sets the difference between the triggering threshold and the end threshold (this
prevents repeated alarm triggering when the reading oscillates around the trigger value). Example: a 5%
hysteresys on a threshold of 100, triggers the alarm when the reading exceeds 100 but it will switch off the
alarm when the reading becomes lower than 95.
The
delay time
sets a time delay for triggering on the alarm after its actual occurrence (or triggering off after
its actual end).
The set up of each alarm is performed on two programming pages prompting the following entry fields
(example for Alarm 1).
(A) Alarm No. and page No. identification (
AL1
= alarm 1 that may be associated to output 1)
(1) Parameter type applying to Alarm 1. The possible choices are:
None
Disabled
U Voltage
f Frequency
I Current
P Active
Power
Q Reactive
Power
S Apparent
Power
PF
Power Factor
U THD
Total Harmonic Distortion (Voltage)
I THD
Total Harmonic Distortion (Current)
(2) Parameter definition: The possible choices are:
LN
Average star value (applicable to voltage, current and THD only).
LL
Average system value (applicable to voltage and THD only).
N
Neutral value (applicable to current only)
Σ
Three phase value (applicable to active, reactive and apparent power only)
