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Certification of Factory Automation Equipment

Posted By Chuck Goetz, Monday, November 01, 2004
Updated: Friday, February 15, 2013

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 CodeArticle 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.

NEC670.1 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 atwww.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.


Read more by Chuck Goetz

Tags:  Featured  November-December 2004 

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