Blue-White Sonic-Pro Hybrid Ultrasonic Flowmeters - Manual (Page 62)

Page 62 Sonic-Pro
Industries, Ltd. Industries, Ltd.
ProSeries
by Blue-White Ind.
TM
8.3.4
More on
Alarm
Conditions
This section contains additional explanation of the conditions under which an alarm
condition is cleared.
The flowmeter will clear an alarm condition automatically if and only if a Release value
has been set for the Trigger value that caused the alarm. For example, if the alarm was
caused by the flow rate falling below the Low Trigger, then the alarm will be
automatically cleared if a Low Release has been set. Whether or not a High Release is
set in this case is of no consequence. If a Release value has not been set, the alarm is
said to be “latched”. A latched alarm can only be cleared if the user presses the CLEAR
soft button and the flow rate has fallen back inside the Trigger values.
The effect of setting an Alarm Delay Time is to add states in which an alarm condition
exists but the relay is temporarily not energized. During these states, the alarm
condition may clear and the relay will then remain de-energized. These states end when
the Alarm Delay Time elapses and if at that time the alarm condition has not cleared
then the relay will energize.
The four combinations of a set Release value (for the alarming Trigger value) and an
Alarm Delay Time are as follows:
Ÿ No Release value, no Alarm Delay Time - the alarm is latched and can only be
cleared by the user pressing the CLEAR soft button when the flow rate has fallen
inside the Trigger value.
! Release value, but no Alarm Delay Time - alarm clears automatically as soon as
the flow rate falls inside the Trigger value (the CLEAR soft button serves no
purpose).
! No Release value, an Alarm Delay Time is set - the alarm is latched (will never
clear automatically) and must be cleared by the user pressing the CLEAR soft
button, however, as well as clearing on the press if the flow is inside the Trigger
value, it will also clear if the flow falls inside the Trigger value while the Alarm
Delay Time is being counted down (the channel is in the CLEARING state).
! Release value and an Alarm Delay Time - the alarm clears whenever the flow
rate falls inside the Trigger value and the purpose of the CLEAR soft button is
only to temporarily de-energize the relay.