Omron VARISPEED F7 User Manual page 289

PID Feedback Loss Detection
When performing PID control, be sure to use the PID feedback loss detection function. Otherwise if the PID
feedback gets lost, the Inverter output frequency may accelerate to the maximum output frequency.
Low Feedback (b5-12 = 1 or 2)
When b5-12 is set to 1 and the PID feedback value falls below the PID feedback loss detection level (b5-13)
for a time longer than the PID feedback loss detection time (b5-14), a "FBL - Feedback Loss" alarm will be
displayed at the operator and inverter operation is continued.
When the same happens and b5-12 is set to 2 a "FBL - Feedback Loss" fault will be displayed on the digital
operator and the inverter operation will be stopped. The motor coasts to stop and the fault output is operated.
The time chart for PID feedback loss detection is shown below.
High Feedback (b5-12 = 3 or 4)
When b5-12 is set to 3 and the PID feedback value exceeds the PID feedback loss detection level (b5-13) for a
6
time longer than the PID feedback loss detection time (b5-14), a "FBL - Feedback Loss" alarm will be dis-
played at the operator and inverter operation is continued.
When the same happens and b5-12 is set to 4 a "FBL - Feedback Loss" fault will be displayed on the digital
operator and the inverter operation will be stopped. The motor coasts to stop and the fault output is operated.
The time chart for PID feedback loss detection is shown below.
106
6-
PID feedback value
Loss detection
level
(b5-13)
Loss detection time
(b5-14)
Fig 6.82 Low PID Feedback Loss Detection Time Chart
PID feedback value
Loss detection
level
(b5-13)
Loss detection time
(b5-14)
Fig 6.83 High PID Feedback Loss Detection Time Chart
No Fbl
detection
Fbl detection
Loss detection time'
(b5-14)
No Fbl
detection
Fbl detection
Loss detection time
(b5-14)
Time
Time