Chapter 1 Overview 7
Liebert NXC 30kVA And 40kVA UPS User Manual
The operation method of ECO mode is the same as the description in Chapter 5 UPS Operation Introduction.
However, in normal mode, the load is powered by the bypass, the inverter indicator is off, and the LCD displays
‘Bypass mode’, and the transfer interval time is less than 20ms.
Warning
Parallel redundancy mode (system expansion)
For higher capacity or higher reliability or both, 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 7-1.
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 suitable for 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 7-4 and Figure 7-5.
Common battery string mode
It means that when the UPS modules (up to four UPSs) are parallel connected, each UPS module can use the same
battery string to achieve the aim of cost-saving, clearance-saving.
Note
The batteries of different manufacturers, different types and different use time are not allowed to be used together. The common
battery string mode is suitable for parallel system only, and does not support the LBS mode.
1.5 Battery Management
The following battery management functions are set by the service engineer through the Emerson setting software.
1.5.1 Normal Function
1. Constant current boost charge
The charge current can be set.
2. Constant voltage boost charge
The maximum boost charge voltage should not exceed 2.4V/cell.
3. Float charge
The float charge voltage should be between 2.2V/cell and 2.3V/cell.
4. Automatic transfer to float charge
When the charge current is less than ‘Threshold of Equalize Charge to Float Charge’ or 0.5A, the charger will
automatically transfer from boost charge to float charge. When boost charge time exceeds the limit of ‘Equalize
Charge Protect Time Limit’, the charger will be forcibly transferred to float charge for protecting the battery.
5. Float charge temperature compensation (optional)
This function must be used together with the battery temperature detection device. The Emerson battery temperature
sensor is a standard option for your selection.
6. EOD protection
When the battery voltage drops to the EOD voltage, the battery converter shuts down automatically and the battery is
isolated to avoid further battery discharge. The EOD voltage is settable from 1.6V/cell to 1.9V/cell (VRLA).
7. Battery low pre-warning time
The battery low pre-warning time is adjustable between 3min and 60min. The default setting is 5min.
8. Maximum battery discharge time
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