Page 183 - Uninterruptible Power Supplies

Rotary UPS Systems
Rotary UPS Systems 181

diesel in full operation both critical and noncritical loads are fed, Fig 3
of Fig. 6.13. Obviously, with such a system the diesel has to be rated for
the full critical and noncritical loads.
Parallel redundancy can be achieved easily in a variety of ways, par-
allel operation of both critical and noncritical loads being possible. Also,
static switches may be used in conjunction with system bypass circuits
to provide a guaranteed noninterrupted load if so required. Figure 6.14
shows the waveform of the output from a parallel redundant 1600-kVA
system with 800-kVA load rupturing a 400-amp motor start fuse. The
photo in Fig. 6.15 is of a parallel redundant system manufactured by
Hitec, installed at a large banking computer center.

Critical
Choke
Output

Non Critical
Output
Induction
Diesel Generator
Coupling
Normal Operation
Fig. 1

Critical
Choke
Output

Non Critical
Output
Induction
Diesel Generator
Coupling
TPS Operation Stage 1 (Mains Failure)
Fig. 2
Critical
Choke
Output

Non Critical
Output
Induction
Diesel Generator
Coupling
TPS Operation Stage 2 (Mains Failure)
Fig. 3
Figure 6.13

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