The torque control system is very important and necessary to the automatic revolving door's safety feature, it was realized mainly by motor and PLC ( Key control unit ), the simple work process is as below .

Firstly we will set a safety area for the revolving door, like the area near the door closing position, then convert this area to the motor's position information .Second, we will develop the program to the PLC (mostly for SIEMENS and LENZE brand), this program is related to the motor and electrical signal . When the door wing revolve into this safety area, the PLC will control the motor's electric current to be a small value, then the output torque of the motor will also become smaller, to guarantee the safe to the people .

Note: both the electric current to the motor and the safety area could be preset .

With the help of this torque control function, when someone enter this safety area and the gap to the closing position is less than the certain distance (within the safety area above), the driving force of the driving system will be reduced, so even if a passerby tries to rush in, he will not be injured.