Safe Torque Off - Sto - Danfoss VLT Safety Option MCB 150 Installation Manual

Installation Guide | VLT® Safety Option MCB 150/151

3.5.3 Safe Torque Off - STO

The safety function Safe Torque Off disconnects power to the motor. It is implemented via the shutdown path of the drive and the safe
outputs of the safety option.
Features of the safety function
• The motor becomes torque-free and no longer generates any hazardous movements.
• To prevent the drive from running down in an uncontrolled manner. In normal operation, activate the safety function Safe Torque
Off via the safety function Safe Stop 1.
• Safe Torque Off is only activated directly when:
- There is an internal error on the safety option.
- The Safe Stop 1 delay time is set to 0.
- One of the inputs, DI1 or DI2, has been selected as Safe Torque Off function.
• The safety function Safe Torque Off corresponds to a category 0 stop (uncontrolled stop) in accordance with EN IEC 60204-1.
Prerequisites for normal operation
• Input DI1 or DI2: "1" Signal (+24 V DC).
• S37 output: "1" Signal (+24 V DC).
Safety function is activated
• By an error after limit values have been exceeded for Safe Stop 1 and Safely Limited Speed.
• By an internal error on the safety option or drive, if the drive can no longer be controlled.
• By executing the safety function Safe Stop 1 (1/0 transition). In this case, the drive is monitored before it is switched to torque-free.
• By download of parameterization via MCT 10 Safe Plug-in if the current drive is running.
• By executing the safety function Safe Torque Off (1/0 transition). This function ensures that no torque-generating energy can
continue to affect a motor and prevents unintentional start-ups.
RISK OF HAZARD
External forces acting on the motor (vertical axis) and unwanted movements, for example caused by gravity, can cause hazards
leading to death or serious injury.
Add measures for fall protection before operating the motor.
-
The STO may be used where power removal is required to prevent an unintended start. The function disables the control voltage of the
drive output stage. Thus, it prevents the drive from generating the voltage required to rotate the motor, see
allows performing maintenance work on non-electrical parts of the machinery without switching off the power supply to the drive.
Danfoss A/S © 2018.09
N O T I C E
Functions and Systems Overview
illustration 7. The function
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