105
Loop Burnout Alarm Section 4-12
• If the set point is so high or low that it cannot be reached even with a sat-
urated manipulated variable, a temperature deviation may remain even in
a steady state and a loop burnout may be detected.
• Detection is not possible if a fault occurs that causes an increase in tem-
perature while control is being applied to increase the temperature (e.g.,
an SSR short-circuit fault).
• Detection is not possible if a fault occurs that causes a decrease in tem-
perature while control is being applied to decrease the temperature (e.g.,
a heater burnout fault).
Parameters Related to Loop Burnout Alarms
Note Set “None” as the unit for analog inputs.
• A loop burnout alarm can be output by setting the alarm 1 type to 12
(LBA).
• A setting of 12 (LBA) can be set for alarm 2 or alarm 3, but the setting will
be disabled.
• Loop burnouts are not detected during SP ramp operation.
• Loop burnouts are not detected during auto-tuning, manual operation, or
while stopped.
• If the alarm 1 latch is set to ON, the latch will be effective for the loop
burnout alarm.
Automatically Setting
the LBA Detection
Time
• The LBA detection time is automatically set by auto-tuning.
(It is not set automatically, however, for heating/cooling control.)
• If the optimum LBA detection time is not obtained by auto-tuning, set the
LBA Detection Time parameter (advanced function setting level).
Parameter name Symbol Setting range Remarks
LBA Detection Time lba 0 to 9999 (s) Setting 0 disables the LBA
function.
LBA Level lbal Controllers with Thermo-
couple/Resistance Ther-
mometer Universal Inputs
0.1 to 999.9 (°C/°F) (See
note.)
Default: 8.0 (°C/°F)
Controllers with Analog
Inputs
0.01 to 99.99 (%FS) Default: 10.00% FS
LBA Band lbab Controllers with Thermo-
couple/Resistance Ther-
mometer Universal Inputs
0.0 to 999.9 (°C/°F) (See
note.)
Default: 3.0 (°C/°F)
Controllers with Analog
Inputs
0.00 to 99.99 (%FS) Default: 0.20% FS
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