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News>Issue Listing>November/December 2004 >Certification of Factory Automation Equipment
| Certification of Factory Automation Equipment |
Factory automation equipment is relied upon to operate many types of industrial manufacturing processes. The ability to automate more and more functions of a manufacturing process has led not only to an increase in the number of machines utilized for a process but also the machines’ complexity. |
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A new factory is being constructed or an
old factory is being updated in your jurisdiction. The owners
of the facility have invested millions of dollars on
industrial machinery that was manufactured in Europe and the
Far East. None of the equipment is listed by a recognized
qualified electrical testing laboratory. The AHJ has the
difficult job of making sure the installation is NEC compliant and needs to advise the owner that in order to
determine whether the equipment complies with safety
requirements they need listed equipment or have the equipment
field evaluated. Are there requirements for these types of
machines that address all the safety concerns with this
equipment? Yes, there are. UL’s Factory Automation Equipment
program can be used to certify this equipment.
Factory automation equipment is relied upon
to operate many types of industrial manufacturing processes.
The ability to automate more and more functions of a
manufacturing process has led not only to an increase in the
number of machines utilized for a process but also the
machines’ complexity. Reduced product life cycles and the
accelerated introduction of new products increases the
frequency of changes to existing manufacturing equipment or
the need to replace or upgrade equipment. Globalization of the
marketplace has also led to an increase in the amount of
imported manufacturing equipment. All of these factors
contribute to challenges for authorities having jurisdiction
to approve the equipment and determine whether the
installation complies with the NEC.
National Electrical Code Article 670
applies to installations of industrial machinery. Section
670.2 describes a number of types of machinery, including
metalworking machinery, plastic injection molding machines,
woodworking equipment, material handling equipment, and
assembly machines. Since the industrial machinery is generally
not a part of the building, Article 670 covers the building
electrical supply circuit for the machinery including minimum
conductor ampacity, disconnecting means and overcurrent
protection. In order to conduct an installation review for the
machinery using the NEC, other NEC articles,
such as Article 430 for motors and motor controllers, would
need to be utilized. Such reviews are dependent on the
knowledge of those examining the equipment, which may lead to
inconsistent applications of the NEC requirements.
NEC 670.1 includes a fine print note
making reference to NFPA 79, Electrical Standards for
Industrial Machinery, for additional requirements applicable
to the electrical assembly of the machine itself. For
jurisdictions where NFPA 79 is cited as an installation code,
NFPA 79 contains detailed requirements that are consistent
with many of the requirements of the NEC, but it also
includes exceptions for constructions commonly utilized by
machinery manufacturers as well as additional requirements for
constructions not normally included as a part of the NEC.
While the installation requirements of the NEC and NFPA 79 address the electrical safety of the installation,
issues related to acceptance of components, especially those
built to international requirements, performance of the
machine and its protection circuits, and safety of the
operators of the equipment is not specifically addressed.
How Can UL Help?
Underwriters Laboratories (UL) can provide a listing for
industrial machinery or provide a field evaluation of the
equipment at the installation site. UL investigations of
equipment that result in a listing demonstrates that
• the machinery was investigated and
tested for safety and includes provisions for installation in
accordance with the requirements of the NEC or NFPA 79,
• machine has been manufactured under a
follow-up surveillance program at the manufacturing location,
and
• application of the UL mark on the
machine at the factory.
When the equipment has not been listed, UL
can perform a field evaluation of the machinery on site
that
• includes a review of the equipment for
compliance with construction and installation requirements,
• includes the ability to conduct limited
performance testing on site, and
• provides an opportunity for AHJ input
on any special concerns or requirements.
Factory Automation
Equipment (GPNY)
UL lists this type of machinery under the category Factory
Automation Equipment (GPNY), located on page 39 in the 2004
General Information Directory for Electrical Equipment
Directory (White Book). This category can also be located on
UL’s Online Certification Directory at www.ul.com/database .
UL listed Factory Automation Equipment is
evaluated for compliance with the Outline of Investigation for
Factory Automation Equipment, Subject 2011. The evaluation
consists of an examination of the components employed in the
machine, examination of the overall machine construction,
performance testing, and review of the mechanical hazards to
operators of the equipment. The requirements of Subject 2011
can provide the basis for UL’s field evaluations on this
type of machinery.
Electrical
Components
A complete review of the components is conducted to determine
that their ratings are suitable for operating the various
parts of the machinery, including motors, heating elements and
lighting. Where components are found without evidence of
listing, the parts can either be evaluated to the appropriate
safety standard or substituted with an appropriate component.
Such machinery may include customized power components such as
solid state motor controllers of adjustable speed drives, or
printed circuits boards for controls. Where evaluation of a
motor controller or control circuit is needed, Subject 2011
references the use of UL 508, Standard for Industrial Control
Equipment. Where adjustable-speed drives are utilized, UL
508C, Standard for Power Conversion Equipment is utilized for
the review and test of the components. Where components have
been marked as being compliant with international standards
such as those of the IEC, the international requirements or
test reports can be reviewed to determine to what extent
additional evaluation to U.S. standards may be required.
Construction
For many machines, the control equipment is installed in a
main control enclosure that is either mounted directly to the
machine or as a separate freestanding cabinet. Subject 2011
references UL 508A, Standard for Industrial Control Panels, to
be used for the evaluation of the component ratings, their
interconnections to the various machine power and control
circuits. Ordinarily, a listed industrial control panel is
marked with the maximum electrical ratings and types of the
intended loads and external control circuit devices such as
sensors or solenoids that are provided remote from the panel
itself. When included as part of the factory automation
equipment, the ratings of loads and control devices are
included and can be directly compared to the component ratings
of the components contained in the control panel. Most
important of these checks is to review the overcurrent
protection devices provided as part of the machinery to
determine whether they are the correct type of device for the
purpose, their ratings conform to UL 508A and the inclusion of
motor overload protection. The overall ratings of the machine
nameplate are calculated in accordance with UL 508A or can be
verified by observation and measurements of various operating
modes of the machine.
Performance
Testing
After the components and assembly have been reviewed, the
machine is operated under normal conditions and reviewed for
temperature rise, operation during overvoltage and
undervoltage conditions and dielectric-withstand tests.
In addition, the machine is tested under
abnormal operating conditions such as single-phasing of the
supply voltage, disabled blower motors, blocked ventilation
openings, single failures of solid state components, and
locked rotor conditions.
Where testing of components is necessary to
determine compliance with U.S. national requirements,
additional tests are performed on printed circuit board
assemblies, individual components or assemblies of components
to the applicable component standard, such as UL 508 or UL
508C.
Mechanical
Evaluation
The machine construction is reviewed for accessible moving
parts of the machine relative to the machine operator. Pinch
points and contact with moving parts or hot surfaces capable
of causing injury are required to be guarded or, where not
possible, marked with a safety cautionary marking. In
addition, each emergency stop button and interlock switch for
machine guards is tested during machine operation to verify
proper shutdown and stopping time for the machine.
Summary
Large industrial factory automation equipment can be certified
by UL as listed equipment at the factory or it can be field
evaluated via the UL-FEP Mark. Subject 2011, Outline of
Investigation, provides the requirements for evaluating
industrial machinery, whether in the manufacturer’s
facilities or at the installation site. Familiarity with
industrial control equipment standards and industrial control
panel standards provides a means to evaluate components and
their interconnections. Factory follow-up inspections of
listed factory automation equipment is conducted at
manufacturing facilities by UL’s global Field Services staff
before the machinery is shipped to the installation site. Over
the past twelve years, since the publication of Subject 2011
Outline, UL has conducted many field evaluations of industrial
machinery. In addition, UL listings for factory automation
equipment continue to increase every year so that UL listing
of these machines is now commonplace. UL certification of
complete assemblies of factory automation equipment provides
the integrity and confidence only the UL mark can provide for
AHJs to review at installation and provide an additional level
of confidence on which to base acceptance of the machinery.
Chuck Goetz is the
primary designated engineer for industrial control
systems and machinery, which includes responsibility for
factory automation equipment, semiconductor
manufacturing equipment, robots and robotic machinery,
enclosures, industrial control panels and motor control
centers. He is currently the principal representative
for UL on CMP-11 and NFPA 79 and has worked at
Underwriters Laboratories Northbrook, Ill., office for
22 years.
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