Watlow PPC-2000 - Manual (Page 120)

Chapter 3: Operating with AnaWin 3 PPC-2000 User’s Guide
96 Watlow Anafaze Doc.# 30002-00 Rev 2.3
High and low process and deviation alarms activate when the
process variable goes outside the limits set by the user. The
alarm remains active until both the process variable comes
within the limit and the deadband, and the alarm is
acknowledged.
Any digital output not used as a control output can be assigned
to a process alarm. The output activates when the alarm is
active. Set the Logic of outputs used with alarms to determine
whether the alarm output turns on or off when an alarm occurs.
An alarm output remains active only as long as the process
variable remains outside the alarm limit and deadband. Once
the process variable is within the limit and deadband, the
output reverts to the inactive state. No alarm acknowledgment
is required.
When the controller powers up or the set point changes,
deviation alarms set to alarm type do not activate until the
process variable comes within the deviation alarm band,
preventing deviation alarms during a cold start. Deviation
alarms set to control type activate whenever the process
variable is outside the deviation band.
Figure 3.2 Process Variable Alarms
Alarm Delay
The controller may be configured to delay alarm reporting.
Alarm Delay delays failed sensor alarms and process alarms for
the channel. Only alarms that are continuously present for
longer than the alarm delay time are reported.
High Process alarm limit
SP + HD Offset
Set Point
SP - LD Offset
High Process alarm on
High Process alarm off
High Deviation
alarm on
High Deviation
alarm off
Low Deviation
alarm off
Low Deviation
alarm on
} Deadband
} Deadband
} Deadband
} Deadband
Low Process alarm on
Low Process alarm off
Low Process alarm limit