6 Chapter 1 Overview
Liebert APM 90 Integrated Modular UPS User Manual
Maintenance mode
As shown in Figure 1-6, if UPS maintenance or repaired is needed, you may use the manual maintenance
switch to transfer the load to the maintenance bypass, with no interruption in power to the load.
Maintenance switch
Mains input
Maintenance bypass
UPS output
Mains input
UPS output
Maintenance switch
Maintenance bypass
Figure 1-6
Schematic diagram of maintenance mode
Warning: risk after load transfers to maintenance bypass
After the UPS is transferred to maintenance bypass, the power modules and bypass module are inoperative and the LCD
has no display, only the green indicator of the input SPD shows that the UPS has mains input, but the output terminals
corresponding to closed output distribution switches and the neutral bars are energized.
Automatic restart mode
The battery becomes exhausted following an extended AC mains failure. The inverters shut down when the
battery reaches the EOD voltage. The UPS can be programmed to automatic restart after EOD after a set
variable delay time. This mode and any delay time are programmed by the commissioning engineer.
During the delay time before automatic restart, the UPS charges the battery so as to avoid power interruption
to load in case of a following power failure.
In case the UPS is not programmed to automatic restart, you can use the FAULT CLEAR key to manually start
the UPS.
ECO mode
As shown in Figure 1-7, in ECO mode, except for the maintenance bypass switch, all power switches and the
BCB are closed, the system prefers to put the load on the bypass mains to save energy. When the bypass
frequency and voltage are in normal range (settable), the load is supplied by the bypass, with the inverter on
standby. When the bypass frequency and voltage are beyond the normal range, the system will transfer to the
inverter. In ECO mode, the battery is normally charged by the charger.
市电输入
整流器
逆变器
电池
电池充电器
UPS
输出
输入开关
逆变自动开关
Mains input
Input switch
Rectifier
Inverter
Automatic
inverter switch
Output switch
Static switch
Charger
Battery
UPS output
Static switch
Rectifier
Inverter
Automatic
inverter switch
UPS output
Output switch
Charger
Battery
Mains input
Input switch
Figure 1-7
Schematic diagram of ECO mode
The ECO mode configuration requires a different setup in the default menu configuration through the
operator control and display panel.