Options
Isolating and voltage matching transformer for the normal and bypass AC source and the load
This transformer, placed in the 1.9 meter high UPS cubicle up to 60 kVA and in an auxiliary cubicle for higher values, may be used to match the bypass AC voltage to that of the inverter, to create galvanic insulation between the load and the Ac sources or to create the appropriate system earthing arrangement.
Harmonics filter and power factor improvement
This option, placed on the normal AC input upstream of the UPS in the 1.9 meter high UPS cubicle for UPSs up to 120 kVA and in an auxiliary cubicle for higher ratings, reduces the reinjection of harmonic currents into the normal AC source. Harmonic reinjection, produced by the rectifier/charger, increases distortion on the normal AC source. The amount of the increase depends on the source impedance. The reduction in distortion reduces the risk of disturbing other sensitive loads connected to the mains. The filter can also increase the power factor upstream of the inverter.
Three types of filter are available:
◗uncompensated filter for the advantages listed above;
◗compensated filter for the advantages listed above and to limit the capacitive current absorbed by the filter (additional inductance), in the event the UPS is supplied by an engine generator set;
◗active harmonic conditioner, the most effective solution because it provides the harmonics drawn, thus allowing the normal AC source to supply a perfectly sinusoidal current. The conditioner may be installed in an auxiliary cubicle or
Safety of life and property
◗backfeed protection. This option, installed upstream of the static bypass, is used to mechanically disconnect the bypass AC source when the system has shifted to battery power or when the bypass AC source has failed. This system is intended to enhance the safety of life and property.