New IEEE Standards

Foster NextGeneration System

Compatibility

By François Martzloff

In an exclusive story, international

standards expert and past Signature

Editorial Board member, François

Martzloff, presents a unique preview of

three new surge-related standards that

are bound to set the course for the

future of system compatibility. This

standards trilogy is scheduled for publication by the Institute of Electrical and

Electronics Engineers early in 2003.

For electronic copies of the new

standards, visit www.ieee.org. For general information about activities of the

IEEE Surge Protective Devices Committee, see grouper.ieee.org/groups/spd.

To access an anthology on surge

protection, go to www.eeel.nist.gov/

811/spd-anthology.

In November 2002, the Institute of

Electrical and Electronics Engineers

(IEEE) approved a set of three standards that provide critical parameters

on the surge environment in lowvoltage ac power circuits, and suggest

improved test methods for end-use

equipment connected to these circuits. When this standards trilogy is

published in early 2003, manufacturers and users of surge protective

devices (SPDs) will have a definitive

set of documents to help them make

more cost-effective and technically

sound design decisions regarding

the compatibility of their equipment

with the surge environment.

The seminal IEEE Standard 587—

Guide on Surge Voltages in LowVoltage AC Power Circuits—has

gone through several revisions,

including a name change to C62.41,

since it was first published in 1980.

A companion, IEEE Standard C62.45

—Guide on Surge Testing for

Equipment Connected to LowVoltage AC Power Circuits—was

also developed to provide guidance

on test procedures.

IEEE 587/C62.41 and C62.45 served

us well from 1980 to 1999. However,

with the availability of new knowledge on surge protection, and after

nearly 20 years of experience in

applying the two standards, a major

update was needed. The newly

developed standards provide a more

direct route to fulfilling the surge

pr

de

m

in

Th

• 

• 

WINTER 2002–2003 • VOLUME 12 • NUMBER 3 A 

TM

Point of View

Ne

Point of View: Continued on back

What we learn about system compatibility (SC) today is vital to a

future that promises increasingly

innovative uses for wireless technologies and microprocessorcontrolled equipment. Industrial

plants will employ more robotic

automation, offices will rely more

heavily on information technologies, and our homes will have

more devices that are controlled

via wireless or the power line.

At utilities, power electronics 

will be used to shape the voltage

and current feeding customer

loads. This proliferation of 

power electronics, coupled with

the growth of wireless communications, will amplify SC

issues in terms of high-frequency,

radiated and conducted, electromagnetic interference.

Until recently, SC research has

focused on power quality phenomena, such as voltage sags and

transients, and their impacts on

equipment performance. But as

the microprocessor becomes

ubiquitous to technology—

making logic voltage lower,

switching speeds higher, and

interference more common—

power quality events may contribute to equipment failure as

well as performance degradation.

Failure analysis techniques are

now being introduced to expand

the scope of SC investigations. 

Utilities are also actively monitoring their grids to characterize the

New IEEE standards will help end users to eva

and to make technically sound and cost-effectiv
6

• IEEE Standard C62.45TM 2002—

Recommended Practice on

Surge Testing for Equipment

Connected to Low-Voltage AC

Power Circuits, which shows how

to perform reasonable, repeatable,

and reliable surge testing.

New Focus

In developing the standards, IEEE

focused on five key areas: transitions,

temporary overvoltages, multipleport equipment problems, scenarios,

and harmonization. Because these

factors can have significant impacts

on hardware selection and specification, they were debated thoroughly

by members of the working group

and other interested parties before a

consensus was reached. Fortunately,

the IEEE standard format includes

“normative” clauses, to emphasize

important points, and “informative”

annexes, to provide perspective on

less definitive issues.

Transitions

Earlier versions of C62.41 offered the

concept of “Location Categories” to

help designers and users of equipment define surge threats by the

general location of the equipment

within a building. Location categories are based on the fact that the

inherent inductance of the building

wiring reduces current stress from

an impinging surge as the distance

from the service entrance increases,

while voltage stress is not affected.

According to this concept, SPDs can

be expected to have less stress exposure as their point of use moves

away from the service entrance.

While the earlier standards did 

not specify precise distances, they 

featured graphic representations

with fine lines, or “boundaries,”

separating location categories.

Because some users focused too

narrowly on these boundaries, the

updated guide now uses the concept

of “Transitions” that connect rather

than separate location categories, as

the graphic shows. These transitions

leave some flexibility for equipment

manufacturers and users in selecting specific surge-withstand values.

Temporary Overvoltages

Although temporary overvoltages—

which last seconds rather than the

microseconds of surges—might be

seen as outside the scope of the

surge environment, their impact on

SPDs can be devastating. For this

reason, IEEE added a description of

their occurrence and mechanism to

the C62.41.1 guide.

Multiple-Port Equipment

Most of today’s electronic equipment

contains multiple ports, with connections to both the ac power supply

and one or more additional systems

that must have a ground reference,

such as phone systems, television

cable systems, and computer networks. Multiple-port equipment is

now the most common victim of

surges. A surge on any of the connected systems will cause a shift in

ground reference potential to appear

across the equipment ports. Guide

C62.41.1 alerts the engineering

community to this phenomenon—

the most frequent source of insurance claims—and supports the

standardization of SPDs. Furthermore, IEEE has just launched two

projects for developing new standards addressing performance and

test methods of multiple-port SPDs.

Scenarios

In an effort to organize and present

information in a way that will be as

useful and realistic as possible, the

standards trilogy introduces the concept of “Scenarios,” which distinguish between two types of surges.

Scenario I describes surges coming

from any source that impinge

upon an installation or are generated within the installation by

load switching. Scenario II covers

surges that are associated with a

rare but possible direct lightning

flash to a building, and with surge

current that exits the building via

the service connection.

The concept of location categories

applies only to surges in Scenario I

—those impinging upon a building from the outside or being generated from within. These are considered to be the vast majority of surge

events. Guide C62.41.1 provides a

surge environment description that

serves as the basis for defining 

waveforms in Recommended

Practice C62.41.2.

The more rare event of a direc

to a building in Scenario II wa

considered to be a special case 

not included in earlier docum

Given the increasing interest i

ramifications of such an event

new standards address this situ

Definitions of appropriate para

ters for this scenario did raise 

discussion in gaining consens

and therefore are proposed in 

informative annex to allow ca

case applications.

Harmonization

In keeping with the transnatio

aim of IEEE standards, the ne

standards were developed to h

nize with related documents fr

the International Electrotechn

Commission (IEC). The IEEE 

ing groups established liaisons 

New IEEE Standards: Continued from front

Overlaps between the lined areas represent “Transitions,” which connect Location

Categories A, B, and C. Stress levels imposed on end-use equipment, including su

protective devices, decrease from C to A for surges impinging upon the facility.
IEC Technical Committees SC37A

(Low-Voltage SPDs) and TC81

(Lightning Protection), as well as

with other parties involved in lightning studies. These efforts will help

to ensure greater credibility and

worldwide acceptance of both IEEE

and IEC standards.

Expanded Scope

In earlier versions of the standard,

surge environment descriptions were

limited to compilations of surge

measurements in the field. The data

were gathered either by systematic

monitoring or through staged tests

during equipment failure investigations. As development of Guide

C62.41.1 progressed, it became clear

that more information on the surge

environment could be gained by

incorporating other data. The standard now includes additional data

from recordings of surge events in

the field, numerical simulations and

laboratory research, and inferences

on the surge environment drawn

from analysis of equipment failures.

The proposed waveforms and associated stress levels in Recommended

Practice C62.41.2 required no major

change during the updating process.

The waveforms should not be construed as specifications—a misconception noted in the use of earlier

versions of C62.41—but rather as a

menu from which equipment manufacturers and users can select stress

levels, as determined by the test

waveform(s) and amplitude(s) best

suited to their own applications. The

menu offers a set of two standard

waveforms for general applications

and a set of two additional waveforms for special applications.

The first standard waveform, the

“Ring Wave,” was constructed in

1980 on the basis of the then-novel

recognition that traditional test

waveforms used in high-voltage laboratories might not provide accurate

representations of the environment

in low-voltage ac power circuits. 

The second standard waveform, the

“Combination Wave,” defines two

stress types. It is used for subjecting

equipment to voltage stress, when the

equipment presents a high impedance, or to current stress, when the

equipment presents a low impedance.

The additional waveforms are the

“Electrical Fast Transient Burst,”

first developed within IEC for electromagnetic compatibility purposes

and adopted by IEEE in 1991, and

the “Long Wave,” which reflects

field observations of surge occurrences. The 1991 version of C62.41

also included a 5-kHz ring wave to

emulate capacitor-switching surges.

This wave was removed from the

menu, as data on the wide range of

capacitor-switching surges made 

it clear that only case-by-case

applications would be reasonable.

Equipped with these waveforms,

Recommended Practice C62.45 provides information on instrumentation, considerations on tolerances 

in the output of surge generators,

and descriptions of test procedures,

including coupling of surges into

test circuits. This enhanced version

addresses issues raised by the shift

from analog to digital instruments

as well as the possible effects of aliasing, insufficient resolution, and

transducer saturation. It also includes

precautions for avoiding artifacts.

With the implementation of the new

IEEE standards trilogy, designers and

users of next-generation devices will

be well equipped to tackle the surge

environment of the future in lowvoltage ac power circuits. Among the

benefits they will realize are more

cost-effective use of resources and

greater reliability of electrical and

electronic equipment. ■

François Martzloff is an Electronics

Engineer at the National Institute of

Standards and Technology (NIST)

(www.nist.gov) in Gaithersburg,

Maryland. He has been at NIST

since 1985, after 29 years at

General Electric, and has contributed to the development of 

IEEE and IEC standards since the

late 1960s. He can be reached at 

f.martzloff@ieee.org.