safe brake test (sbt)

A Safe Brake Test (SBT) is an automated diagnostic function in industrial machinery that verifies a motor's holding brake can provide sufficient braking torque to prevent unwanted axis movement, crucial for safety in applications like lifts or presses; it works by the drive applying torque against the engaged brake and using an encoder to detect if the axis moves beyond a set tolerance, indicating a fault requiring service or replacement.

 

Working:

• Torque Application: The drive temporarily generates a torque (force) in the opposite direction of the brake's hold.
• Encoder Monitoring: An encoder precisely measures the axis's actual position and speed.
• Tolerance Check: If the axis moves more than a defined limit (e.g., >1% of max speed), the brake isn't holding adequately, triggering a fault.
• Automated Shutdown: An identified fault prevents further operation, safely shutting down the machine. 

Key aspects

• Diagnostic, not control: SBT confirms brake health, it doesn't control the stopping action itself.
• Requires encoder: A high-precision encoder is necessary for accurate position feedback.
• Frequency: Can run every cycle or every few hours, depending on risk analysis.
• Prevents failure: Detects brake wear or issues before they cause accidents, reducing maintenance surprises