CS to replace malfunctioning charger of UPS A1 at 10:00- 18:00 on Dec 8th. 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.UPS A1 battery charger failure alarm, the battery charging control board needs to be replaced.Power resources A to IT devices will be running on by-pass, shut down UPS A1, replace the battery charge control board. After completing UPS A1 maintenance, switch back to UPS power supply and resume power supply.Check all UPS alarms and control settings against original specification and adjust where necessary.