2011 EMC Directory & Design Guide - Interference Technology

adiated emissions
G o ing from A n a l o g t o Digi ta l
Going from Analog to Digital
Radiated emissions performance of a
nuclear plant control system from 10 kHz to 6 GHz
Philip F. Keebler
EMC Group, Electric Power Research Institute
Knoxville, Tennessee USA
Stephen Berger
TEM Consulting, LLC
Georgetown, Texas USA
Nuclear power plants (NPPs) in the
United States have been undergoing
upgrades from analog instrumentation
and control (I&C) equipment to digital
equipment over the past several years. Upgrades
have been occurring on the plant
floor for systems such as generator controls,
turbine supervisory controls, and chiller
controls as well as control systems in the
plant control room. Plant events involving
electromagnetic interference (EMI) continue
to occur with existing analog equipment
and with some digital equipment. Because
of the increased focus on safety and efforts
to eliminate plant events, electromagnetic
compatibility (EMC) is still a growing concern.
The migration from analog I&C equipment
to digital I&C equipment warrants the
need to investigate the EMC characteristics
of changing electromagnetic environments.
These characteristics have been identified
through Electric Power Research Institute
(EPRI) research by conducting long-term
emissions measurements before analog
I&C systems are removed, and then again
after new digital I&C systems were installed
and operational. This paper presents the
first-of-its-kind analysis of a complete set of
radiated emissions measurement data from
100 Hertz to 6 GHz as part of an upgrade
inside a control room to replace an analog
control system with a digital control system
for one operating unit of a nuclear plant in
the United States.
Keywords- Digital upgrade, control
room, radiated emissions, electromagnetic
interference
INTRODUCTION
Electromagnetic characterization of spaces
where electrical and electronic equipment
must coexist is a necessary function of EMC
for reasons discussed below. These spaces
include areas inside and outside facilities
that serve residential, commercial, industrial,
and specialty needs such as healthcare
and power plants. Operations of equipment
in these spaces create the overall electromagnetic
environment (EME).
Diverse Equipment Designs and
Design Changes
About the only commonality between electronic
equipment in today’s modern world,
including digital I&C equipment used to
upgrade older analog I&C equipment in
existing power plants, is the need for equipment
to use AC or DC power to operate.
With rapidly changing semiconductor
technologies, the growing use of new digital
devices, and the proliferation of software
development and its embedded use to
enhance the I&C functions of NPPs, I&C
equipment manufacturers are developing
new types of I&C equipment. The need for
smaller more efficient equipment with faster
processing speeds and increased network
connectivity with higher reliability causes
an increase in radiated and conducted
emissions. Although filtering and shielding
90 interference technology emc Directory & design guide 2011