UPS for 400 Vac Grid, User Guide, doc. rev. 4
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For example, the bypass frequency is a nominal 50 Hz, and you have set the frequency tracking
range to be ±2 Hz. In this case, as long as the bypass frequency remains within the range of 48–
52 Hz, the inverter frequency will mirror it. When the bypass frequency passes these boundaries,
the inverter frequency ceases to be determined by the bypass frequency and comes under the
control of the UPS's internal clock (this is called "free-running mode"). When the bypass
frequency returns to the range of 48–52 Hz, free-running mode ceases and the inverter frequency
again comes under the control of the bypass frequency.
8.2.1.2.
Setup > System > Number of modules
This function is used to inform the UPS of:
Number of power modules installed:
Sets the max. system inverter load capacity. The number of power modules can be equal to or
less than the max. power rating of the UPS.
Number of modules for redundancy:
Must be less than the total number of power modules installed (up to an N-1 configuration).
By indicating the number of power modules that are to provide redundancy, you are also
defining the maximum system inverter load capacity
8.2.1.2.1.
Redundancy
"Redundant" modules are those in excess of the minimum number of modules required to supply
the maximum expected UPS load. Each UPS module can supply 30 kVA. So, for example, if the
maximum expected load is 120kVA (4 x 30 kVA), and there are five power modules installed, one
of them can be designated for redundancy. In the event one of the five modules fails, the
redundant module ensures that the UPS will continue to be able to accommodate the maximum
expected load.
The number of redundant modules can be zero or greater, depending on the maximum expected
load and the number of available module shelves.
In reality, redundancy is not a property of any particular module. Redundancy is simply the
presence of one or more modules in excess of the number of modules required to meet the
maximum expected load.
As an example, let's say:
We have a UPS system with five module shelves. Each shelf can hold a 30 kVA module.
The maximum expected load is 120 kVA, and four modules (120 kVA) are required to supply the
maximum expected load.
A fifth module can be installed and a redundancy of one module declared. If any one of the
four modules fails, the UPS will still be able to supply power for the maximum expected load
(4x30 kVA). If all of the modules are operating normally, and the load unexpectedly increases
