SuperNova PD500 PID Process & Temperature Controllers
Instruction Manual
41
Alarm Operation Examples
High Absolute Alarm Operation
The example below illustrates the operation of a high
absolute alarm The alarm turns on when the set point
entered in parameter AL-x is reached, where x can be
any of alarms 1, 2, 3, or 4. The alarm resets when the
PV is below the set point by the Ax.DB number.
Figure 28. High Absolute Alarm Operation
Alarm Standby Mode Operation
Alarms with standby mode will ignore the alarm
condition when the alarm on condition is satisfied at
the time of power on, changes from STOP to RUN
mode, an SV change, or a change to the alarm
program settings. The standby alarm will turn on after
the alarm release condition has been set.
In the below example, when power is applied to the
controller and operation begins, the PV is already in
the alarm state, being greater than the AL-x alarm set
point. In the case of the standard high absolute alarm,
the alarm turns on. However, if a high absolute alarm
with standby is used, the alarm will not turn on until
after the PV passes below deadband and reset point,
and then returns to the higher alarm state.
Figure 29. High Absolute Alarm Operation
without Standby
Figure 30. High Absolute Alarm Operation
with Standby
Alarm Number n Latch Status
(An.LS)
An.LS is the alarm latch reset function, where n can
be any of alarms 1, 2, 3, or 4. This parameter is
accessible if the Sub Relay Group (G.SUB) parameter
An.LT is set to ON.
If the Sub Relay Group (G.SUB) parameter An.LT is
set to OFF, this parameter does not appear in the
menu. The alarm will automatically reset when the
alarm condition is cleared (including deadband).
Releasing an Alarm in Latch State
To release an alarm with the latch status ON, the
operator must change this parameter to RST after the
alarm condition has cleared (including the deadband).
As a shortcut, the operator may press the DOWN or
UP arrow keys to reset a latched alarm after the alarm
condition has cleared (including the deadband).
Figure 31. High Absolute Alarm with Latch
Function
Loop Break Alarm (LBA)
The loop break alarm (LBA) is a special type of alarm
used to alert operators to a heater break, wiring error,
output circuit problems, or other issue with the control
loop.
When the control output value in PID or on/off control
modes reaches 0% or 100%, the LBA monitors the
rate of process variable (PV) change. If the PV does
not change by at least the loop break set value
amount over the loop break alarm time, the LBA turns
on.
Reverse Action LBA Operation
When the control output value is 100% in the reverse
action mode (heating control), the LBA alarm output
turns on when the temperature does not rise at least
the LB.SV value within the LB.TM set time. Also,
when the control output value is 0%, the LBA output
turns on when the temperature does not fall at least
the LB.SV value within the LB.TM setting time.