IEEE C62.48:2005 pdf download.IEEE Guide on Interactions Between Power System Disturbances and Surge- Protective Devices.
This guide applies to surge-protective devices (SPDs) manufactured to be connected to 50 Hz or 60 Hz ac power circuits rated at 100 -1000 V rms.
This guide describes the effects on SPDs of power system disturbances occurring in these low-voltage ac power circuits. The disturbances are not limited to surges. The effects of the presence and operation of SPDs on the quality of power available to the connected loads are described. The interaction among multiple SPDs on the same circuit is also described.
This guide discusses both voltage and current surges. The current surges discussed in this guide are the result of voltage surges. Current surges that are solely the result of load changes and do not result in voltage increases, such as a short circuit, arc not discussed in this guide.
An SPD’s primary purpose is to provide surge protection. Devices discussed in this guide contain at least one nonlinear component for diverting surge current and!or dissipating surge energy, such as a metal oxide varistor (MOV), silicon avalanche diode (SAD), thyristor, or spark gap. Uninterruptible power supplies (UPSs), ferroresonators, motor-generators, and filters containing only inductive and/or capacitive components are not considered SPDs in this guide.
1.2 Purpose
The purpose of this guide is to provide information on the interactions between power system disturbances and SPDs that is not readily available in other standards. This guide provides summary information on power system disturbances that affect or can affect SPDs. The description of the interactions is intended to inform the potential user of such SPDs as to what can be expected from such devices.
NOTE—Data used for the preparation of this standard were obtained primarily from low-voltage ac power distribution systems used in North America.
3. Definitions
For the purposes of this guide. the following terms and definitions apply. The Authoritative Dictionary of
IEEE Standards Ternis [B3]4 should be referenced for terms not defined in this clause.
3.1 nonlinear load: An electrical load that draws current discontinuously or whose impedance varies during the cycle of the input ac voltage waveform.
3.2 nonlinear load current: Load current that is discontinuous or is not proportional to the ac voltage.
33 power cross: An event in an electrical distribution system where a higher voltage conductor, such as from a transmission line, falls on a lower voltage conductor, such as a distribution or secondary line.
4. Power system disturbances
Power system disturbances arc increases or decreases in the system voltage or the power frequency beyond what is considered the normal tolerance (e.g., as described by ANSI C84. l). The changes in voltage on the ac mains can range from complete loss (no voltage) for various durations lasting up to seconds, minutes. or even hours to very high-magnitude, short-duration impulses of 50 or more times the normal system voltage lasting for no more than a few millionths of a second. Some of these disturbances can have an undesirable effect on the connected equipment, including SPDs. The SPDs discussed in this guide are connected to the low-voltage mains (100-1000 V ac), though some of the disturbances originate on the high-voltage distribution system. SPDs are intended to reduce the severity of some power system disturbances but can be unable to do anything about others.
Before discussing the interactions between power system disturbances and SPDs in detail, the power system disturbances will be described along with a brief summary of the interactions. Table I presents a summary of the interactions.IEEE C62.48 pdf download.