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OFF
LINE UPS:
This system is basically an
OFF-LINE UPS system. In this system, the output waveform is synchronized
with the Mains waveform. Thus the change over the inverter mode is faster (about
2ms)compared to the common OFF-LINE
UPS. Compounded with automatic Voltage Regulator
(AVR). This may be a cost-effective solution for a stand-alone computer where power conditions
are less severe. For LAN application though, it is questions. Firstly, whenever mains
power is available, it is directly given to the load though it is controlled to some extent
by the built-in AVR. Thus the load is not completely isolated from the mains. The
Differential mode noise (DMRR) can be greatly attenuated in this systems, however
the Common Mode noise (CMRR) is still passed on to the computer. Moreover, if this
is such a good system that it can replace an ON-LINE UPS system, one wonders why
the same companies who manufacture LINE-INTERACTIVE system, also
manufacture the ON-LINE systems.
ON-LINE UPS:
This system is basically a double conversion system. In this system,
the Mains power is first converted to DC voltage of appropriate value and fed to the
inverter that converts it back to AC power. Thus in this system, the load is always
powered by the inverter. The battery is connected to the DC bus. Thus this is truly a
No-Break system. The load being totally isolated from the Mains power, DMRR as
well as CMRR noise is filtered out and the load gets clean power.
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