The BJFR to replace malfunctioning charger of UPS A1 [from 10:00 HK time till 14:00 HK time, Dec 8th, 2019]. Power resource A to IT devices will be running on by-pass. There will be potential risk of half power redundancy loss in case of utility power suspension. UPS B1 and STS mounted on each rack will be supporting comms room/closet during that time.