YASKAWA T1000A Technical Manual page 132

5.2 b: Application
n
PID Feedback Loss Detection
The PID feedback loss detection function can detect broken sensors or broken sensor wiring. It should be used whenever
PID control is enabled to prevent critical machine conditions (e.g., acceleration to max. frequency) caused by a feedback
loss.
Feedback loss can be detected in two ways:
• Feedback Low Detection
Detected when the feedback falls below a certain level for longer than the specified time. This function is set up using
parameters b5-12 to b5-14.
• Feedback High Detection
Detected when the feedback rises beyond a certain level for longer than the specified time. This function is set up using
parameters b5-12, b5-36, and b5-37.
The following figure explains the working principle of feedback loss detection when the feedback signal is too low.
Feedback high detection works in the same way.
Figure 5.23
n
b5-12: PID Feedback Loss Detection Selection
Enables or disables the feedback loss detection and sets the operation when a feedback loss is detected.
No.
b5-12
Setting 0: Digital Output Only
A digital output set for "PID feedback low" (H2-
detection level set to b5-13 for the time set to b5-14 or longer. A digital output set for "PID feedback high" (H2-
3F) will be triggered if the PID feedback value is beyond the detection level set to b5-36 for longer than the times set to
b5-37. Neither a fault nor an alarm is displayed on the digital operator. The drive will continue operation. When the
feedback value leaves the loss detection range, the output is reset.
Setting 1: Feedback Loss Alarm
If the PID feedback value falls below the level set to b5-13 for longer than the time set to b5-14, a "FBL - Feedback
Low" alarm will be displayed and a digital output set for "PID feedback low" (H2-
PID feedback value exceeds the level set to b5-36 for longer than the time set to b5-37, a "FBH - Feedback High" alarm
will be displayed and a digital output set for "PID feedback high" (H2-
an alarm output (H1-
range, the alarm and outputs are reset.
Setting 2: Feedback Loss Fault
If the PID feedback value falls below the level set to b5-13 for longer than the time set to b5-14, a "FbL - Feedback Low"
fault will be displayed. If the PID feedback value exceeds the level set to b5-36 for longer than the time set to b5-37, a
"FbH - Feedback High" fault will be displayed. Both events trigger a fault output (H1-
stop the motor.
132
PID feedback value
PID
Feedback
Detection
Low Level
(b5-13)
PID Feedback
Low Detection Time
Figure 5.23 PID Feedback Loss Detection
Parameter Name
PID Feedback Loss Detection Selection
= 10). The drive will continue operation. When the feedback value leaves the loss detection
no FbL
detection
PID Feedback
Low Detection Time
(b5-14) (b5-14)
= 3E) will be triggered if the PID feedback value is below the
YASKAWA ELECTRIC SIEP C710616 30B YASKAWA AC Drive T1000A Technical Manual
time
FbL detection
Setting Range
0 to 5
= 3E) will be triggered. If the
= 3F) will be triggered. Both events trigger
= E) and cause the drive to
Default
0
=