Compliance Questions
Welcome to Compliance Questions. At LTG Services we get many questions from our clients regarding product compliance. We would like to post your
questions and our responses regarding product compliance on this page.
Please E-mail questions, comments and suggestions to webmaster@ltgservices.com
IP Hosedown Test
I have a question regarding the Hosedown test in the IP standard. I am looking for
equipment to perform this test. Is there a company that supplies this type of equipment
and what equipment models would be required to run this test?
The only place that I was able to find follows:
PTL Dr. Grabenhorst Gmbh Industrielstrasse 15 D-8652 Stadtsteinach Germany
49 92 25 9 86 0
Fax: 49 92 25 9 86 40
Additionally, we work with a local company that designs most of our test fixtures and
custom test equipment. They probably will not have IEC 529 on hand and will request a copy
or the specifications within.
RPI Inc 4139 Rickenbacker Drive Atlanta, GA 30342-3076
404-256-5944
Fax: 404-256-0609
Class 2 Power Supplies
Where can I find the requirements for classifying a power supply as "Class
2"? What agency/organization set this?
The original Class 2 requirements can be found in Article 725 of the National
Electric Code (NEC, NFPA-70) and Section 16 of the Canidian Electric Code (CE Code,
C22.1).
The US and Canadian standards for evaluating power supplies are UL 1310 (Class 2 Power
Units) and CAN/CSA-C22.2 No. 223 (Power Supplies with Extra-Low-Voltage Class 2 Outputs),
respectively.
The agencies are the National Fire Protection Association and the Canadian Standards
Association.
Industrial Computers and UL 1998
How difficult is it to get a UL and CE mark on a small industrial computer?
What other certification should it get?
What is UL 1998 (see attached), and how difficult would the testing procedure be for
this mark? (See attached.)
According to Flynn, who is responsible for developing investigation protocols for
applying UL 1998, interest has come from U.S. organizations developing medical device
regulations, OSHA, and the U.S. Voluntary Safety System. In Europe, interest has been
expressed by those developing gas/oil, machinery, and medical device directives, she says.
The updated UL 1998 version addresses risks that may result from faults caused by software
errors, including the following: design errors, such as incorrect software algorithms or
interfaces; coding errors, including syntax, incorrect signs, and endless loops; timing
errors that can cause premature or late program execution; induced errors caused by
hardware failure; latent, user, input/output, range and other errors that are only
detectable when a given value or set of conditions occurs; and failure of the system to
perform any function at all.
Flynn is hopeful UL's voting process will be completed by fall, and official American
National Standards Institute (ANSI) approval is received by this December. Software
suppliers conforming to UL 1998 receive a "Programmable Systems Certificate"
specifying that their product meets the standard's requirements.
Research Triangle Park, N.C. -- Underwriters Laboratories (UL) this month plans to
begin the voting process on a significantly revised version of a UL standard created to
prevent programmable logic controller (PLC) software failures that could cause fire,
electric shock, or personal injuries. Aimed primarily at PLC manufacturers and PLC
software suppliers, the proposed Second Edition of the Standard for Safety-Related
Software, UL 1998, addresses potential risks unique to equipment controlled by software.
UL 1998 initially was aimed primarily at residential control systems, such as gas- and
oil-fired appliances, temperature controls, and fire-alarm and suppression systems, says
Robert A. Williams, UL corporate manager, standards and research. The updated edition has
broader applications, addressing risks that may occur as a result of faults caused by
errors in non-networked embedded microprocessor software.
"Growing recognition of the potential risks associated with microprocessor-based
control is stimulating internationally harmonized standardization activities that address
the extension of product safety standards to include requirements for safety management of
products employing microprocessor-based controls," says Janet S. Flynn, UL research
engineer. According to Flynn, who is responsible for developing investigation protocols
for applying UL 1998, interest has come from U.S. organizations developing medical device
regulations, OSHA, and the U.S. Voluntary Safety System. In Europe, interest has been
expressed by those developing gas/oil, machinery, and medical device directives, she says.
The updated UL 1998 version addresses risks that may result from faults caused by
software errors, including the following: design errors, such as incorrect software
algorithms or interfaces; coding errors, including syntax, incorrect signs, and endless
loops; timing errors that can cause premature or late program execution; induced errors
caused by hardware failure; latent, user, input/output, range and other errors that are
only detectable when a given value or set of conditions occurs; and failure of the system
to perform any function at all.
Flynn is hopeful UL's voting process will be completed by fall, and official American
National Standards Institute (ANSI) approval is received by this December.
Software suppliers conforming to UL 1998 receive a "Programmable Systems
Certificate" specifying that their product meets the standard's requirements.
The level of difficulty varies from product to product and manufacturer to
manufacturer. Some products pass all construction and test requirements from the start and
get approval immediately. On the other hand if major enclosure changes or board changes
are required, the approval may take longer. I have listed out the standards and generic
test program that would be applicable. To provide more specific information a detailed
product description will be needed.
UL approval on an industrial computer would require evaluation to UL 508, Industrial
Control Equipment and if safety of personnel was at risk dependent on the computer and
software UL 1998, Safety-Related Software could also be applied.
UL 508 would consist of evaluation of the product with regards to fire, shock and
safety hazards. Typically the materials used would be required to posses electrical and
mechanical ratings for the environment they were being used in. For a computer, plastics,
printed wiring boards and power supplies would be of concern. Additionally, the user
should not have access to certain voltage levels or moving parts.
UL 1998 is mainly directed at safety issues if the computer software malfunctioned. I
am obtaining some information that will assist you.
The CE mark would require evaluation to the following Standards:
EN 61131-1, 2 and 3
EN 61131-X consists of safety and EMC requirements. Most of the safety issues would be
addressed under UL 508 and UL 1998. The EMC requirements would require ESD, Radiated
Susceptibility and Fast Transients per the 801 series of standards. Emissions testing
similar to FCC Part 15 may also be required.
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