Page 522 - Handbook of Electrical Engineering

ABBREVIATIONS COMMONLY USED IN ELECTRICAL DOCUMENTS 513

OSHA Occupational Health and Safety Administration (USA).
OV or O/V Overvoltage.

P

P or W Active power, watts.
PA Public address system.
p or s Laplace operator in mathematics, for transfer functions.
PC Programmable controller or personal computer.
PAM Pulse or pole amplitude modulation.
PCC Point of common connection.
PB or Pb Lead metal.
PBWB Phosphor bronze wire braid.
PBCU or TCU Tinned copper.
PELV An extra-low voltage system similar to SELV but connected to earth at
some point.
P & ID Piping and instrument diagram.
PF or pf Power factor.
Ph or ph Phases of an electrical circuit.
pk or peak Peak value of an instantaneous quantity.
PLC Programmable logic controller.
PMS Power management system.
POL Polyethylene.
PTB Physilalish Technische Bundesanstalt.
PTP Polyethylene terephthalate.
PTFE Polytetra fluoro ethylene.
pu or p.u. Per unit.
PVC Polyvinyl chloride.
PVDF Polyvinylidene fluoride.
PWM Pulse width modulation.

Q

Q Reactive power, volt-amperes-reactive.
QA Quality assurance.
QC Quality control.

R

R or r Electrical resistance.
Rad or rad Angular displacement in radians.
RAM Random access memory.
RCU Remote control unit.
Ref. or REF. Reference.
rem or (R) Remote operation.
RHS Right-hand side.
RMS, rms Root mean square.