KEB COMBIVERT S6 Series, Installation Manual

GB - 20

Safety Function STO

Characteristic data for „Safe torque off“

•

Power supply for the rotation direction of the motor is interrupted (free-wheeling motor)

• Used when monitoring of standstill is not necessary
• Unintentional starting of the motor is prevented
• No galvanic isolation of the motor from the inverter DC link

What is realized by the STO function related to EN 60204 ?

Emergency stop can be realized by the STO function, since the mains voltage may remain 

effective.

Emergency stop can be realized only in connection with a line contactor, which disconnects 

the mains voltage !

3.1 

Emergency stop according EN 60204

By using suitable safety switchgear units, stop category 0 and 1 according to EN 60204 can 

be reached by the STO function in the system. Note chapter 6 for safety switchgear units.

Stop category 0

„uncontrolled stop“, i.e. stop by immediate removal of power to the 

actuators.

Stop category 1

„controlled stop“, i.e. power to the actuators is retained to apply 

braking until the stop is achieved. The energy is switched off at 

standstill.

Emergency stop to EN 60204 must be functional in all operating modes of the drive module. 

The reset of emergency stop may not lead to an uncontrolled start of the drive.

Restart  

only after  

confirmation

The drive restarts if function STO is no longer released. In order 

to comply with EN 60204, it must be ensured by external meas-

ures that the drive restarts only after confirmation.

Without mechanical brake the drive leads to coast; motor is free-wheeling. Additional protec

-

tive devices must be installed (e.g.locking systems) if damage to persons or property can 

occur.

Ensure coast 

of the motor

If danger to persons occur after switching off the motor control 

by STO, the entrance to hazard areas must remain closed until 

the drive stops.

Jerks in error 

case

In case of double malfunction it can lead to unwanted jerk, the 

rotation angle is depending on the number of poles of the se-

lected drive and the gear ratio.

Calculation of the jerk:

Rotation angle of the jerk W

R

 [°] =

180°

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Pole-pair number p • gear reduction ratio g