Frequency converter mode
The UPS can be programmed into frequency converter mode for either 50 Hz or 60 Hz stable output frequency. The input
frequency may vary from 40 Hz to 70 Hz. Under this mode, it is required to open the maintenance bypass switch to disable
the static bypass operation, and the battery becomes optional depending on any requirement to operate in battery mode. The
frequency converter mode can be set by the service engineer through the setting software.
Parallel redundancy mode (system expansion)
For higher capacity or reliability, the outputs of multiple UPS modules can be programmed for directly paralleling while a built-
in parallel controller in each UPS module ensures automatic load sharing. The parallel system can be composed of up to four
UPS modules. For the operation principle diagram of the parallel redundancy mode, see Figure 8.1 on page129.
LBS mode
A dual bus system consists of two independent UPS systems, each containing one or more parallel UPS modules. The dual
bus system has high reliability and is applicable to the load with multiple inputs. For single-input load, an STS can be installed
to power the load. For the operation principle diagram of the LBS mode, see Figure 8.5 on page137 and Figure 8.6 on page138.
Dynamic online mode
As shown in Figure 2.8 on the facing page, if this mode is selected, all power switches and the battery switches are closed
except for the maintenance bypass switch, and the system prefers to put the load on the bypass, to achieve the aim of
energy-saving. When the load power is fed by bypass supply, the inverter is in the mode of power quality compensation for the
bypass voltage. When the voltage of the bypass supply is beyond the predefined and adjustable limits, the system will transfer
to the inverter output. In this mode, the system can normally charge the battery.
2 Overview
13
Vertiv™ Liebert® APM Plus User Manual
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