Page 242 - Power Quality in Electrical Systems

224 Index

Three-phase rectifiers, 4, 35 230-V single-phase, 134
amplitude variation in, 40 Typical run time, 133
commutation in, 35
neutral current in, 55–56 Ultimate availability, 113
with nonlinear loads, 56–58 Ultracapacitators, 144–145
notching and, 35 Unavailability, 113
Total demand distortion (TDD), 78 Unbalance (see Voltage unbalance)
Total harmonic distortion (THD), 2, 53 Uninterruptible power supplies (UPSs),
example, 58 119–121, 129–145
with line reactors, 81 application of, 10
load current harmonics affecting, 58–61 batteries, 138–139
rms value of, 53 battery-inverter UPS, 119, 120
of sine waveforms, 53 commercially available, 133–137
of square waveforms, 53 concept of, 129–131
Transfer function, 207 as correction measure, 164
Transfer switches, 198–200 cost of, 10
applications of, 199–200 data sets and, 124, 125
automatic electromechanical, 198 double-conversion, 129–130
by-pass, 198 E/G sets and, 110–111, 124,
in E/G sets, 198–200 193, 199
solid state, 199 for energy storage, 137–138
types of, 198–199 energy storage in, 133
UPSs with, 193 with feeders, 194
utility, 194 flywheels, 139–141
Transformers, 120–122 fuel cells, 141–143
constant voltage, 120 history of, 131–133
distortion factor standard for, 5 on ITIC curves, 151
grounding, 122 line-interactive, 130–131, 191
harmonic currents with, 72–74 modular, 136
harmonics affecting, 44 online, 133, 191
relay, 5 with PCs, 191
shielded isolation, 10 with servers and PCs, 191
standards for, 5 for standby power systems, 190
for standby power systems, 190 with transfer switches, 193
substation, 120 types of, 133–145
in twelve-pulse rectifiers, 121 ultracapacitators, 144–145
utility substation, 120 with utility transfer switch, 194
Transients, 7, 8, 41 UPSs (see Uninterruptible power
Trapezoidal waveforms, 46 supplies)
Triangle waveforms, 44, 52 Utility power, 132, 199
harmonics of, 45 Utility substation transformers, 120
infinite Fourier series for, 44 Utility switching, 1
rms value of, 52 Utility transfer switch, UPSs with, 194
square waveforms vs., 45 Utilization equipment, 110
Triangular ripples, 50–51
Triplen (triple-n) harmonics, 4 Valve-regulated lead-acid (VRLA)
“True rms” multimeters, 201–202 batteries, 139
Truncated Fourier series, 53 Variable-speed drives, 211
Tuning, in passive filters, 95 Varistors, metal-oxide, 7
Twelve-pulse converters, 115 V h , 78
Twelve-pulse rectifiers, 70–71 Voltage:
for large ASDs, 178 load, 58–61
transformers in, 121 mitigating disturbances, 10