Applicable Systems
EFC
FEX
FEI
HNC
Symptoms
Safe deceleration process timeout. The safety system is monitoring the deceleration rate and has detected that the actual deceleration is slower than the configured safe deceleration rate.
Possible Causes
- Actual motor deceleration slower than the safe deceleration parameter
- Brake resistor unable to absorb regenerative energy, causing DC bus overvoltage and reduced braking torque
- Mechanical brake worn or not applying full braking force
- Safe deceleration parameter set too aggressively for the load
Troubleshooting Steps
- Step 1: Check the safe deceleration parameter in IndraWorks AS
Deceleration value is achievable with the available braking torque - Step 2: Verify brake resistor capacity is adequate for the regenerative energy
Resistor power rating exceeds calculated regenerative power - Step 3: Test mechanical brake torque if the application uses a brake
Brake provides rated holding/braking torque - Step 4: Adjust safe deceleration to match achievable performance after safety review
Updated deceleration is achievable within system limits
How to Reset
1) Check safe deceleration parameter. 2) Verify brake resistor capacity. 3) Test brake. 4) Adjust parameter after safety review. Caution: Safe deceleration parameters must be validated by calculation per the safety assessment.
Frequently Asked Questions
- Q: What is the difference between F7050 and F7051?
F7050 monitors total stop time (must reach zero speed within timeout). F7051 monitors the deceleration rate itself (must decelerate at or above the safe rate). Both are safety-monitored stop functions.
- Q: Can I disable safe deceleration monitoring?
No. Safe deceleration monitoring is a safety function that cannot be disabled. It must be correctly configured for the application.
Source: Rexroth IndraDrive Safety Integrated Manual, Bosch Rexroth AG
Category: PLC & VFD