BU I LDI NG SOLUT IONS
— Static UPS
Choosing the power of an uninterruptible power supply is an operation that involves elements of various kinds, both functional and normative.
The main elements that must be considered can be summarized as:
Typical values of Î UPS e t UPS can range from typical current values of 150% of nominal for one minute up to 200% for 100ms in the absence of mains or for non- bypassed UPS systems. In the event of overloads in the presence of a mains supply, operation will switch to bypass mode with a higher current rating. In the case of distorting loads, the system is not normally downgraded for non-linear loads normalized according to IEC EN 62040-3 with crest factor less than three (3:1). For higher values, contact the manufacturer.
• two of the following parameters of the loads to be supplied Active Power (PRL), Apparent Power (SRL) or Power Factor (P.F.); • type of load power supply (Voltage, Frequency, number of phases); • coefficient of contemporaneity of the loads; • required autonomy; • type of network power supply (Voltage, Frequency, number of phases).
If the load is special and requires a high inrush current, for example, this must be taken into account. Known parameters:
• Î UPS (maximum current value from the UPS); • t UPS (the time for which ÎUPS is sustainable); • Î load (overload current required by the load);
the sizing apparent power will be:
. Î load Î UPS
S UPS = S RL
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