Dear Fellow Compliance Colleague,
You are invited to the joint meeting of IEEE New England
Section EMC Chapter and Northeast Product Safety Society, Inc.
on Wednesday September 25, 1996 7:00p.m. featuring
presentation and follow up discussion:
A Close Look at the New EC Power Line Harmonics Requirements
by Isidor Straus, Curtis-Straus, Littleton, Massachusetts.
Last fall, the European Commission adopted the new IEC/CENELEC
on power line harmonics, IEC 1000-3-2/EN61000-3-2, as a mandatory
requirement under the EMC Directive. The standard restricts the
harmonic components of the current drawn by all AC mains connected
equipment operating at less than 16 Amperes per phase, and applies
to all equipment using more than 75 Watts. The EMC community knew
of the standard and expected it to be designated under the EMC
Directive.
The manner in which it was adopted, however, came as a great shock:
there was virtually no transition period. Equipment was expected to
comply with the new requirements as of the beginning of 1996. The
standard way of designing electronic power supplies-both linear and
switching, was essentially outlawed overnight! The authorities are
working
to soften the blow by introducing a transition period, but the fact
remains
that in the near future, if not immediately, electronic equipment must
be
designed with the harmonic requirements in mind. This knowledge has
caused a lot of consternation in the EMC community. Electronic power
supplies commonly incorporate full-wave diode rectification and a bulk
storage capacitor as the input to further linear or switching regulation
circuitry. It is the threshold action of these components that causes
current to flow in a narrow period near the peak of the applied mains
voltage. The addition of an additional pulse-width modulated inductor
can change this current profile, but that technology is not yet widely
disseminated and will initially command a premium. At this time, it is
important to know whether or not a product actually needs to have a
specially engineered power supply, or if it can use an older one.
Although the standard technically applies to equipment drawing more
than 75 Watts (approximately 1/3 Ampere), in fact a more careful
analysis
shows that equipment drawing substantially more power-up to nearly
200 Watts--can still meet the harmonic requirements.
The 75 Watt level is not a "cast in stone" limit-it is used because it
contains
a large enough safety margin that equipment at that level is so unlikely
to
fail the requirements as to not be worth testing. The talk presents a
mathematical analysis which profiles equipment harmonic currents as a
function of RMS current and conduction phase angle. These parameters
can easily be measured with common equipment. Armed with this
information,
it is possible to decide early in the design cycle whether the new
harmonic
requirements will impose any hardship.
Isidor Straus has been professionally involved with product compliance
issues, with an emphasis on electromagnetic compatibility matters, since
1977. He is presently the Chief Scientist at Curtis-Straus, LLC, of
Littleton,
Massachusetts. Curtis-Straus provides a wide range of regulatory
testing
and consulting services. He also serves as a managing editor of the
periodical Compliance Engineering. Previously, he was a co-founder of
Dash, Straus, and Goodhue, Inc., where he was Vice President of
Engineering
until 1988. Mr. Straus holds a BSEE from M. I. T., and a Master's of
Science
degree in finance from Boston College. Mr. Straus is also registered as
a
Professional Engineer in Massachusetts.
Directions: The meeting will take place at EMC Corporation on September
25, 1996 at 7 p.m. We gather at EMC at 7:00 p.m. for networking and
munchies,
courtesy of EMC, the technical meeting starts at 7:30 pm. EMC
Corporation is
located in Hopkinton, Massachusetts. Take Route 495 to Exit 21B. Bear
right
at the bottom of the ramp and turn left onto South Street at the traffic
light. EMC
Corporation's Training Facility is located at 42 South Street, which is
the first right
after turning onto South Street. The meeting will be held in the EMC's
Customer
Briefing Center.
Prior to the meeting, socializing will be at O'Tooles Pub/North Pond
House
on South Street, on the right side, about a 1/2 mile past EMC's Customer
Briefing Center from 5:00 to 6:45 p.m., where food and drink may be
purchased.
For more information, please call Mirko Matejic at (508) 549-3185.
Further information on NPSS, Inc. can be found at:
http://www.safetylink.com/npss.html
Further information on IEEE EMC Society and link to many related sites
can be found at: http://www.emclab.umr.edu/ieee_emc/
