Page 287 - Electrical Safety of Low Voltage Systems

Overcurrent devices
in TN-S systems, 123–126, 123f, 124t
in TT grounding system, 99–102, 100f, 100t, 101f
Overvoltage, 159–161, 159f
definition of, 201
external overvoltage
earthing systems and, 209–210, 210f
induced overvoltage, 210–212, 211f
safety against, 201–212
temporary overvoltage
ground faults in IT systems, 206–208, 207f, 208f
ground faults in TN systems, 202–204, 203f, 204f
ground faults in TT systems, 204–206, 205f, 205t, 206f
types of, 201

P
Parallel protection system, 31
Passive sign convention, 273, 274f
Patient leakage current, 256, 256f
Patient vicinity, 256
PE. See Protective conductor
PELV. See Protective extra-low voltage
PEN. See Neutral-protective conductor
Permissible body current, 81, 81f
heart current factor, 82f, 83–84, 84t
human size and, 82–83, 82f
Permissible prospective touch voltage, 87–90, 87f, 88t, 89t, 90f
Phasors, 270f, 271f
definition of, 267–268f
sinusoids and, 268–270
PMs. See Protective measures
Prospective step voltage, 7
Prospective touch voltage, 6, 51
Protective bonding conductor, 4, 5f
Protective conductor continuity test, 239–240, 240f
Protective conductor (PE), 4, 181, 185–193, 186t
iterative method of calculation, 190–191, 191f
metallic layers of cables, 192, 192f, 193f
minimum cross-sectional area calculation, 186–190, 187t, 190t
Protective extra-low voltage (PELV), 171, 175f
application of, 176–178, 177f
equipotential bonding in, 176f