Omron E5AZ, User Manual

Page: 105 / 208

82
Loop Break Alarm
Section 4-11
• 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 Break Alarms
Note Set “none” as the unit for analog inputs.
• A loop break alarm can be output by setting the alarm 1 type to 12 (LBA).
• The ALM1 indicator will light when a loop break is detected.
• Loop breaks are not detected during SP ramp operation.
• Loop breaks 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
break 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).
Determining the LBA
Detection Time
• To manually set the LBA detection time, set the “LBA detection time”
parameter to twice the LBA reference time given below.
1,2,3... 1. Set the output to the maximum value.
2. Measure the time required for the width of change in the input to reach the
LBA band.
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
MV = 100%
PV
Temperature
Time
Measurement time
Tm
LBA band
LBA detection time = Tm
×
2