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47DT OPERATING MANUAL EM-9508-B Rev.7
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ALARM ACTION BASICS
Alarm trip operates in relation to the display value. Alarm indicators, except for ‘P’ indicator, do not turn on until all param-
eters (display value, deadband, ON delay time elapsed) of the setpoint become true. Display color is switched accordingly
with “green (normal) to red (alarm)” or “red (normal) to green (alarm)” selected for the display color parameter. ‘P’ indicator
normally turns on when no other indicators are on. It turns off during ‘no measuring’ status in the event trigger mode, dur-
ing the alarm power ON delay time period and during the standby sequence period. ‘P’ indicator, as an exception, remains
on during ON/OFF delay time even when another alarm indicator may be on (Figure 1).
Figure 1: Example of high alarm trip and indicators action with ON/OFF delay time
(1) ON delay time is triggered when the display value exceeds the H setpoint.
Alarm is handled as ‘non-confirmed’ during ON delay or OFF delay time period. ‘P’ indicator always turns on during this
non-confirmed time period.
(2) ‘H’ indicator turns on after the ON delay time tH has elapsed. ‘P’ indicator turns off.
(3) OFF delay time is triggered when the display value falls below the H setpoint. ‘P’ indicator turns on.
(4) ‘H’ indicator turns off after the OFF delay time tL has elapsed.
(5) ON delay time is triggered again but is reset within the ON delay time period. ‘H’ indicator remains off.
Figure 2: Normal setting
Figure 3: Zone setting
Display value
H alarm setpoint
L alarm setpoint
HH alarm output (hi)
L alarm output (lo)
‘HH’ indicator
‘P’ indicator
‘L’ indicator
HH alarm setpoint
LL alarm setpoint
H alarm output (hi)
LL alarm output (lo)
‘H’ indicator
‘LL’ indicator
Display value
H alarm setpoint
L alarm setpoint
HH alarm output (hi)
L alarm output (lo)
‘HH’ indicator
‘P’ indicator
‘L’ indicator
HH alarm setpoint
LL alarm setpoint
H alarm output (hi)
LL alarm output (lo)
‘H’ indicator
‘LL’ indicator
In the normal setting, alarm trips according to the
setpoint and the trip action (direction) setting. The P
status means the zone where the LL, L, H and HH alarm
outputs are OFF.
In the zone setting, alarm trips and resets between each
setpoint. Alarm trip action setting is disregarded with
zone alarm.
H alarm setpoint (hi)
Display value
‘H’ indicator
‘P’ indicator
H setpoint / high trip, tH = H ON delay time, tL = H OFF delay time
tH
tL
tH
(1)
(3)
(2)
(4)
(5)
Time
