Start
Input ground wire is
connected rightly?
Connect Ground wireY
Restart UPS and no
alarm?
EndN
Whether the input neutral wire and
live wire are reversely connected
Y
Y
Connect L & N
wire rightly
Y
Restart UPS and no
alarm?
N End
Replace PSDR
Y
Restart UPS and no
alarm?
N
Replace UPS
End
UPS
PSDR
End
Repair detection
circuit
Restart UPS and no
alarm?
N End
CNTL
Replace CNTL
PCBA
Y
Restart UPS and no
alarm?
EndN
Y
Whether the voltage is close to 0
Volt?
Check the voltage between input
neutral wire and ground wire
Check the power
distribution system of the
grid
N
the voltage between input neutral wire and
ground wire
is close to 0 Volt
Restart UPS and no
alarm?
EndN
Y
Repair detection
circuit
Restart UPS and no
alarm?
EndN