User manual
Liebert GXTMT Series     Installation and User Manual 
1-3 kVA UPS 
Page  20  V2.11  Emerson Network Power 
Trouble Shooting 
10. Trouble Shooting 
If the UPS system does not operate correctly, please attempt to solve the problem using the table below. 
Problem Possible cause  Remedy 
No indication, no warning 
tone even though system is 
connected to mains power 
supply 
No input voltage  Check building wiring socket outlet 
and input cable. 
LINE LED blinks  Phase and neutral 
conductor at input of UPS 
system are reversed 
Rotate mains power socket by 180° 
or connect UPS system. 
LINE-LED blinks and 
BATTERY-LED lights up 
Input power and/or 
frequency are out of 
tolerance 
Check input power source and inform 
dealer if necessary 
LINE and BYPASS LED light 
up even though the power 
supply is available 
Inverter not switched on  Press On-Switch “I” 
INVERTER LED lights up, 
and audible alarm sounding 
every 1 beep in every 4 
seconds 
Mains power supply has 
failed 
Switching to battery mode 
automatically. When audible alarm 
sounding every second, battery is 
almost empty. 
FAULT LED lights, warning 
tone once a second 
Overload  Remove loads of UPS output. 
FAULT-LED lights up, 
permanent warning tone 
UPS fault  Notify dealer 
Emergency supply period 
shorter than nominal value 
Batteries not fully charged 
/ batteries defect 
Charge the batteries for at least   
1 - 2 hours and then check capacity. 
If the problem still persists, consult 
your dealer. 
FAULT LED lights, 
BATTERY-LED blinks, 
warning tone once a second   
Charger or Batteries 
damaged 
Notify dealer 
Please have the following information at hand before calling the After-Sales Service Department: 
1.  Model number, serial number 
2.  Date on which the problem occurred 
3.  Detailed description of the problem 










