2 Chapter 1 Overview
APM 300 Integrated UPS Single Module And Parallel System User Manual
Table 1-1 UPS component configuration
Component
Quantity (pcs)
Remark
Main power cabinet
1
Standard component
Switch cabinet
1
Standard component
Bypass module
1
Standard component
Power module
1
~
10
Mandatory option. Installed at site
1.3
Design Concept
1.3.1
System Design
As shown in Figure 1-2, the AC mains source is converted by the rectifier into DC power. The inverter converts
that DC power from the rectifier or the DC power from the battery into AC power, and provides the AC power
for the load. The battery powers the load through the inverter in the event of a power failure. When the
inverter is faulty or turned off, the mains source can also power the load through the static bypass.
Input
Maintenance bypass switch
Bypass input switch
Rectifier input switch
Bypass input
Mains input
Battery charger
Output switch
Automatic inverter switch
Inverter
Rectifier
Static switch
Maintenance bypass
UPS output
Battery
Output
Input
Output
Bypass input
Mains input
Rectifier input switch
Rectifier
Maintenance bypass switch
Bypass input switch
Battery
Battery charger
Inverter
Static switch
Automatic inverter switch
Maintenance bypass
Output switch
UPS output
Figure 1-2
System schematic diagram
If UPS maintenance or repair is necessary, the load can be transferred to the maintenance bypass without
power interruption.
1.3.2
Bypass
The circuit block labeled static switch in Figure 1-2 contains an electronically controlled switching circuit that
enables the load to be connected to either the inverter output or to a bypass power source through the static
bypass line. During normal system operation, the load is connected to the inverters; but in the event of a UPS
overload or inverter failure, the load is automatically transferred to the static bypass line.
During normal operating conditions, the inverter output and bypass supply must be fully synchronized so as to
achieve a clean (no-break) load transfer between the inverter output and static bypass line. The
synchronization between the inverter output and static bypass is achieved through the inverter control
electronics, which make the inverter frequency track that of the static bypass supply, provided that the bypass
remains within an acceptable frequency window.
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