________________________________________________________________________________
EVO STAR 60-800
57
B
INPUT TWELVE PULSES AND FILTERS
B.1
INPUT TWELVE PULSES
Twelve pulses is a particolar rectifier system. Usually rectifier is a double controlled bridge made with SCR. In this
configuration input current has a typical
wave as in picture B1. This solution has
a THD of 30% (usually) because there
are fifth and seventh harmonic. The
problems for this type of input wave are
amplificated in case of generator, (is
necessary plan a generator power three
time or more than UPS power. In a
UPS with input twelve THD is typical
of 12% with input current wave as in
picture B2.
Picture B1
Picture B2
