47
UPS for 480 Vac Grid, User Guide, doc. rel.4.0
Before modifying the UPS nominal frequency, the UPS must be turned off by means of the
ON/OFF button on the System Menu screen. Obviously, the nominal system frequency chosen
should be the same as the nominal frequency of the rectifier input and bypass voltage.
Frequency tracking range. The Inverter frequency is normally governed by the frequency of
the bypass voltage, which will be a nominal 50 or 60 Hz. There may be natural fluctuations in
the bypass frequency. The frequency tracking range lets you determine how far away from the
nominal frequency the Inverter will follow the bypass frequency. When the bypass frequency
fluctuation exceeds the frequency tracking range, the Inverter stops following the bypass
frequency and begins instead to determine its frequency by means of the UPS's internal clock
according to the nominal frequency.
For example, the bypass frequency is a nominal 60 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 58–62 Hz, the Inverter frequency will follow 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 according to the nominal frequency
(this is called "free-running mode"). When the bypass frequency returns to the range of 58–62
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
Number of redundant modules 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.
Number of dc blocks
Each dc converter module (providing 60kW) is made up of two dc converter blocks, (providing
30kW each) for the right and left. At least one dc converter module is required, for every two
power modules in the system. For systems with an odd number of power modules, the total
number of dc converter modules must therefore be increased by one, in order to insure the
