Watlow Series F4S/D - Manual (Page 73)

Wa t l o w S e r i e s F 4 S / D F e a t u r e s ■ 6 . 9
Alarm Latching
A latched alarm will remain active after the alarm
condition has passed. It can only be deactivated by
the user. An alarm that is not latched (self-clear-
ing) will deactivate automatically when the alarm
condition has passed.
Location in software: Setup Page > Alarm x (1 or 2).
Figure 6.9a — Alarm Latching.
Normal Operating Range
Alarm High
Set Point
Time
Te
mperature
Alarm Low
Set Point
The alarm state continues until the
temperature drops to the alarm high
set point minus the hysteresis. A
latching alarm could be turned off by
the operator at this point. A non-
latching alarm would turn off
automatically.
The alarm state begins when the temperature
reaches the alarm high set point.
Process
Temperature
Alarm Hysteresis
Alarm Silencing
Alarm silencing has two uses:
1. It is often used to allow a system to warm up
after it has been started up. With alarm silenc-
ing on, an alarm is not triggered when the pro-
cess temperature is initially lower than the
alarm low set point. The process temperature
has to enter the normal operating range beyond
the hysteresis zone to activate the alarm func-
tion.
2. Alarm silencing also allows the operator to dis-
able the alarm output while the controller is in
an alarm state. The process temperature has to
enter the normal operating range beyond the
hysteresis zone to activate the alarm output
function.
If the Series F4 has an output that is functioning
as a deviation alarm, the alarm is silenced when
the set point is changed, until the process value re-
enters the normal operating range.
Location in software: Setup Page > Alarm x (1 or 2).
Figure 6.9b — Alarm Silencing.
Normal Operating Range
Alarm is
enabled
here.
Alarm
is triggered
here.
Startup,
alarm is
disabled.
Time
Temperature
Alarm High
Set Point
Alarm Low
Set Point
Process
Temperature
Hysteresis
Hysteresis
Alarm Sides
Alarms can be configured to trigger when the pro-
cess exceeds the High Alarm Set Point, the Low
Alarm Set Point or both.
Location in software: Setup Page > Alarm x (1 or 2).
(Alarm set points are established in the Operations
Page.)