OnLine Power Battery Backup System - Manual (Page 9)

OLP
Three Phase UPS Systems
1. SYSTEM OVERVIEW
1-5
1.2. Features and Advantages
(a) Reliable input protection: Circuit breakers are placed in each individual
input branch to ensure power can continue through another branch in case of
breaker trip caused by an abnormal condition in either rectifier or load.
(b) Input surge protection: An MOV (surge protector) is added at the input,
providing protection to both UPS and the load from any lightning surges, or
surges caused by neighboring large loads.
(c) EMI suppression: An EMI filter is added to meet the international EMC
limits. Very low noise is emitted, and no interference is back-feed to other
equipment connected to the same AC source.
(d) Ruggedness: The rectifier employs phase control technology to regulate the
DC link voltage. This is the most efficient method to charge the batteries. The
SCR used are inherently rugged. Additionally, a large inductor is added at the
input to avoid deforming the AC source waveform.
(e) High frequency design: The inverter uses high frequency, high efficiency
IGBT, PWM methodology to convert the DC power to AC power. The number
of components is fewer, reliability is improved, and the size and weight of UPS
is reduced, performance is improved, and acoustic noise is minimized.
(f) True Galvanic isolation: An isolation transformer is placed at the output.
This solves the problem of poor input grounding, can allow a different ground
between input and output, can avoid the annoying problem of ground leakage
current, and can be tied to any potential provided on site. The AC output is
isolated under every mode of operation. Additionally, the load receives the
bonus of attenuation of common mode noise from the output isolation
transformer.