UL 1778 UPS Equipment requires that a fixed UPS has a disconnect
switch for its output (or a cord and plug or receptacle on the output).
Otherwise (according to UL 1778) the UPS instruction manual
should require that you provide a disconnect device on the
UPS output.
However, these
If the UPS is contained within an enclosure where the output receptacles or
the UPS on-off switch is not accessible to the user as is the case in some
Kiosk applications, an external Kill Switch that is accessible to the user
is required to disconnect the output of the UPS to the product.
This is
The requirement for a remote emergency power off switch is taken from
Annex NAE 2.6.11 of UL 1950, Section 645-11 of the NEC.
The following is the reply I received from UL regarding this issue,
and in particular that it only applies to computer rooms. Note
the last sentence.
The source of the
Hello all,
When doing EMI scans of ITE, I have always worked with a margin of 2 dB
less than the actual limit. No test house I have ever been to will give a
meets the requirements... without having this margin. Can anyone point
out if this is an actual requirement built into any of the standards,
Greetings,
Is any one familiar with a requirement/s that specify or limits the
color of light (LEDs) indicators used on test or industrial type
equipment per the function?
Does ISO 3864 include this information?
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This message is coming from the emc-pstc discussion list.
To cancel your
The way I understand it
Each directive is written differently. The Machinery and EMC directives
are structured so that supporting data must be made available in a
reasonable amount of time. This allows the data to reside in the U.S.
for U.S. manufacturers. However, the Low Voltage Directive
2 dB was the required margin for initial acceptance to the VDE standard for
ITE. Of course, the VDE standards are no longer mandatory since the EMC
Directive came into effect. The new thinking today is to take measurement
uncertainty into consideration when determining a pass/fail criteria. For
Scott,
There is no requirement for a minimum passing margin built into FCC Part
15, CISPR 22 or EN 55022.
Minimum passing margin of 2 dB was mentioned in old, now obsolete VDE
EMC specifications. There is 2 dB rule in CISPR procedures to determine
representative configuration in a case of
I once read an article (IEEE, 1992), entitled: Measurement Comparisons
of Radiated Test Facilities. The Abstract sez:
. . .A total of 44 sites worldwide were tested
involving both Open Area Test Sites (OATS) and Semi Anechoic Chambers
(SAC). Preliminary results of the study
It is my understanding that this margin is a carryover from VDE
requirements where for statistical reasons you need 2.2 (?) dB margin in
order to infer that from a single unit test, your other units will also
comply. It is also my understanding that that margin was waived when 3-8
units were
I am looking for opinions from group members on the advantages and
disadvantages between a 10m anechoic chamber and a 10m OATS.
All input is appreciated.
Thanks
Joe Martin
EMC/Product Safety Engineer
P.E. Biosystems
marti...@pebio.com
Hi,
In the interest of not divulging proprietary info, I will not
specify the companies involved although I can say that I
have never worked for either the manufacturer or the
test lab.
But I have seen a final report from a very reputable lab
and written for a very reputable company that only
I second what Lauren said. People usually don't include proprietary
information (schematics, drawings, etc.)in their CE compliance technical
documentation that must be kept within the Community. --Barry Ma
-
Original Text
From: Crane, Lauren lcr...@aus.etn.com, on
Okay here I go starting another forest fire!
Before answering the question I will put in my two cents worth.
Regardless of what the test house does I would strongly urge you not to
accept equipment for production with a single sample test that measures
close to the limit. A onesy-twosy kind of
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