YASKAWA U1000 Series Technical Manual page 207

■ 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 5.25
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- = 3E) will be triggered if the PID feedback value is below the
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 time 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, an "FbL - PID Feedback
Loss" alarm will be displayed and a digital output set for "PID feedback low" (H2- = 3E) will be triggered. If the
PID feedback value exceeds the level set to b5-36 for longer than the time set to b5-37, an "FBH - Feedback High" alarm
will be displayed and a digital output set for "PID feedback high" (H2- = 3F) will be triggered. Both events trigger
an alarm output (H2- = 10). The drive will continue operation. When the feedback value leaves the loss detection
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, an "FbL - PID Feedback
Loss" 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, an "FbH - Feedback High" fault will be displayed. Both events trigger a fault output (H2- = E) and cause the
drive to stop the motor.
YASKAWA ELECTRIC SIEP C710636 02B YASKAWA U1000 Technical Manual
PID feedback value
PID
Feedback
Low Detection
Level
(b5-13)
PID Feedback
Loss Detection Time
(b5-14)
Figure 5.25 PID Feedback Loss Detection
Parameter Name
PID Feedback Loss Detection Selection
no FbL
detection
FbL detection
PID Feedback
Loss Detection Time
(b5-14)
Setting Range
5.2 b: Application
time
Default
0 to 5 0
5
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