1) The obstruction detection of the PSD system works by comparing the expected motor current with the measured motor current over the door speed profile. In response to an obstruction, the PSD involved will firstly release the door closing force and then attempt the closing of the PSD again after a short duration. If an obstruction is still detected, the door set will recycle the door opening and closing sequences up to 3 attempts. Afterward, alarm will be raised by the system and the respective DOI will be illuminated in Red.