Xtreme Power Conversion Corporation
E90 Service Manual
Page 5
Uninterruptible Power Supply
System block diagram
AC/
DC
DC/DC
CHARGER
EMI
EMI
DC/AC
EMI
mains
batter
B
ps switch
Output
output
B
attery fuse
fuse
Block diagram
As shown above, there is a bypass switch. When switch on it, the power will go to the bypass road. Then UPS will
detect the output switch and bypass voltage, frequency and phase sequence. If output switch is on, both the volt-
age and frequency of bypass are in the range, the UPS will send out bypass output commands and meanwhile the
bypass LED will be on.
Close the main switch, if the mains voltage, frequency and phase sequence are in the range, UPS will soft start.
When bus voltage rises around 170V, PFC boost begins to work and the bus voltage will be up to about 200V.
Inverter starts. When inverter is ready, it will transfer to inverter mode. If bypass voltage, frequency and phase
sequence are normal, the inverter voltage will track the bypass power and switch to inverter output without in-
terruption, or the UPS will transfer to inverter intermittently. Inverter LED on and bypass LED off, the inverter will
provide power. If the battery is normal, the UPS will activate the charger to charge the battery.
UPS detects maintenance air-switch at any time. When remove the baffle of the switch, UPS will transfer to bypass
status. Now close the maintenance air-switch for supplying power from bypass. When finish maintenance, the air-
switch cannot be open until the UPS is in bypass, or it will cause the power down of load.