Specifications

Configuring Alarms for Points
PlantScape Server and Client Configuration Guide 159
PV Low
A PV Low alarm is generated when the PV falls below the specified limit.
PV Low Low
A PV Low Low alarm is generated when the PV falls below the specified
limit, which must be less than the PV Low limit.
Deviation High and Deviation Low
A Deviation Low alarm is generated when the PV drops below the SP by the
value:
• For a positive range, for example, 0 to 100, this will be a negative
number.
• For a negative range, for example, -100 to 0 (rarely used), this will be a
positive number.
A Deviation High alarm is generated when the PV goes above the SP by the
value:
• For a positive range, for example, 0 to 100, this will be a positive
number.
• For a negative range, for example, -100 to 0 (rarely used), this will be a
negative number.
Example A point has an SP of 80, and you want to generate:
• A deviation low alarm when the PV drops below 75
• A deviation high alarm when the PV rises above 90
You would set the limits as follows:
Deviation Low Alarm Limit = - 6
Deviation High Alarm Limit = 11
Note To suppress deviation alarms for the time a control loop needs to
follow a new setpoint, set the point’s control timeout to the required delay
time. After this time has elapsed a deviation alarm will be generated if the
deviation is still outside the specified deviation limits.
Rate Of Change
A Rate Of Change alarm is generated when the rate of change of the PV
exceeds the specified rate of change limit. The limit is specified in
engineering units per second.
Transmitter Low
A Transmitter Low alarm is similar to the PV Low alarm. It can be used to
indicate a failed transmitter signal.
plscpcg.book Page 159 Monday, May 28, 2001 10:11 AM