Técnicas De Protección

Surge Protection Techniques in Low-Voltage AC Power Systems
François D. Martzloff
General Electric Com pany
Schenectady NY

Reprinted , with permission, from Proceedings, INTELEC '79
(International Telecommunications Energy Conference), 1979
Significance
Part 6: Tutorials, textbooks and reviews
A tutorial review paper describing the origins of surge voltages and the standardizationefforts to
characterize these surges.
T he principles of operation are described for “crowbar devices” (now generally described under the
standardized nam e of “voltage switching devices”) and for “voltage clam ping devices: (now generally
described under the standardized nam e of “voltage lim iting devices”). Failure m odes are aslo discussed.
Briefly m entions one of the early experim ents toinvestigate the coordination between a voltage-switching
arrester and a downstream varistor that gained growing recognition in the eighties and nineties. That
subject is addressed by several subsequent papers in Part 8 of the SPD Anthology.

SURGE PROTECTION TECHNIQUES IN LOW-VOLTAGE AC POWER SYSTEMS

F.D. Martzloff
Corporate Research and Development
General Electric Company

ABSTRACTDesigners involved in the ac power side of telecommunications equipment have been justifiably concerned with surge protection because field experience is
rich in case histories of failures attributable to transient
overvoltages. Insufficient knowledge of the exact nature
of these overvoltages, however, has made t h e ~ r task
difficult in the past.
After several years of data
collection by anumber of organizations, a more definitive
understand~ngof the surge environment is emerg~ng. The
next few years' publications from the IEEE, the IEC,
N EMA, and other interested groups will document that
understanding. This paper presents an overview of the
results of data collection and environment descriptions
from the point of view of telecommunications power
supply problems, as well asa review of applicable
techniques and devices.

INTRODUCTION
From the early days of the introduction of semiconductors, voltage surges have been blamed for device
failures and system malfunctions. Silicon semiconductors
are, indeed, sensitive to overvoltages, more so than their
predecessors, such as the obsolete copper oxide or
selenium rectifiers. From an early period of frustration
andpoor knowledge of the actual environment, progress
has been made both in the area of defining the environment and of providing new surge protective devices and
techniques to deal effectively with the problem.
Recent progress in the technology of transient
voltage suppressors has opened new opportunities to
improve the level of protection of semiconductors exposed
to power system transients.In the past, direct exposure
to outdoor system surges required surge arresters with
high energy capability to survive the discharge currents
associated with direct or indirect lightning effects, at the
cost of voltage-clamping levels that were too high to
protect sensitive semiconductors. The approach a t that
time was a coordinated combination of arresters and lowvoltage suppressors, anapproach that is still valid in many
cases. It is now possible, however, to apply a single
suppressor, with sufficient capability to withstand outdoor
surges while clamping a t a level low enough to protect
power semiconductors such as power supply rectifiers.
Examples of coordinated protection as well as the
application of high power surge suppression devices, with
experimental verificationof performance, will be given in
the paper.

CH1.502-417910000-0086$00.75@ 1979 IEEE

T HE ORIGIN OF SURGE VOLTAGES
Two major causes of surge voltages have long been
recognized: system switching transients and transients
triggered or excited by lightning discharges (in contrast to
direct lightning discharges to the power systems, which
are generally destructive and for which economical...