A Guide to Motor Compliance Standards
At face value, the purpose of compliance is to ensure a product meets basic safety requirements and has been designed with good engineering practices and built with quality manufacturing processes so it poses little threat to the consuming public. On a much larger scale, compliance affects national and international trade and, in some cases, may reduce product liability litigation for the manufacturer. Compliance engineering is no doubt a very broad topic that covers many activities from initial product design through manufacturing and workplace safety. This article discusses the basic elements, organizations and testing involved with compliance engineering, including information specific to the compliance of electric motors. In general, compliance is broken down into the following categories:
- Health and safety designs and construction
- Energy efficiency
- Electromagnetic compatibility (EMC)
Workplace Safety Compliance:
- Worker safety
Agencies and Organizations
Compliance standards are developed by governmental agencies and independent (third party) organizations. There are numerous agencies involved with standards writing; 1they write both mandatory and advisory (consensus) standards. Mandatory standards can be developed by governmental agencies or independent organizations and are made into law. Advisory (consensus) standards are developed by independent organizations as recommendations for safe practices; many times, all or part of these recommendations become mandatory standards.
The main agencies involved electric motor compliance and electrical safety standards are:
- Underwriters’ Laboratories (UL): an independent, third party, testing organization that publishes over 250 safety standards and certifies the safety of products.
- Canadian Standards Association (CSA): an independent testing organization that certifies motors to its standards.
- Institute of Electrical and Electronic Engineers (IEEE): a technical organization that recommends safe practices, which often become mandatory standards. Regarding motors, the IEEE publishes standards on temperature rise, rating methods, classification of insulating materials.
- American National Standards Institute (ANSI): a national organization that writes consensus standards that represent manufacturers, distributors and consumers. Its standards cover topics such as dimensions, specifications of materials, methods of test, performance, definition of terms, etc. Its primary motor standard is C-50: Rotating Machinery.
- National Electrical Manufacturers Association (NEMA): an employer association that participates in writing voluntary standards in conjunction with the IEC and represent general practices in the industry. “It participates extensively in the IEC at both technical and management levels and provides support for six IEC Technical Committees (TCs).” For motors, its standards cover frame sizes, torque classifications, and basis of rating.
- International Electrotechnical Commission (IEC), a global non-governmental organization that prepares and publishes international standards for electrical, electronic and related technologies. Several of its standards are highly relevant for motor manufacturing. IEC 60034 is referred to by regulators for the classification of electrical motor efficiency.
- International Organization for Standardization2 (ISO): a non-governmental organization that promotes the development of standardization around the world. For motor manufacturing, the two major ISO standards are ISO9000, which focuses on quality assurance in manufacturing; and ISO14001, which focuses on environmental management systems.
- The European Committee for Electrotechnical Standardization (CENELEC): Based in the European Union (EU), it writes standards to develop harmonized electrical standards for the European community. To sell motors in the EU, a manufacturer must comply with EU standards for the CE mark.
Workplace and Worker Safety Compliance
While much of compliance engineering is accomplished in the design and manufacturing stages of a product’s life cycle, it does not end when the product is shipped from the factory. Compliance extends into the workplace with standards for workplace safety, installation (construction) and maintenance. The regulatory standards bodies3 involved with workplace safety compliance are the American National Standards Institute (ANSI), Institute of Electrical and Electronic Engineers (IEEE), the National Fire Protection Association (NFPA), American Society for Testing and Materials (ASTM), American Society of Safety Engineers (ASSE), Occupational Health and Safety Administration (OSHA), National Electrical Safety Code (NESC), and the National Electrical Code (NEC) (sponsored by the NFPA).
The regulatory bodies cited above typically produce voluntary (advisory) standards developed by industry professionals from public/private organizations with two exceptions: OSHA and the NEC. OSHA’s requirements are legal, hence, mandatory, so “failure to follow these standards could result in a citation, a work shutdown, fines or other sanctions.”4 The NEC, sponsored by the NFPA,5 has been “adopted by local law in many states, municipalities, cities and other such areas.” 6 In fact, many countries outside of the U.S. have adopted the NEC in all or part of their national installation code. OSHA’s health and safety regulations are detailed in its 29 CFR 1910 Subpart S on Electrical Safety. This standard covers a broad range of electrical safety issues7 that are relevant to the installation and maintenance of electric motors. 8 To assist in the compliance of its regulations, OSHA provides technical consultations, voluntary protection programs and training & education. 9
Independent Testing: Third Party Certifications
To verify conformity to compliance standards, a manufacturer must submit its product to an independent or third party for testing and certification. 10 In the U.S., there are a number of independent testing laboratories with the most common being UL and CSA. For motor testing and compliance, tests will be conducted to ensure “compliance with the norms of design, material inputs and manufacturing accuracy. It determines the mechanical soundness and electrical fitness of the machine for its electrical and mechanical performance.” 11
Depending on the application, UL tests electric motors according to the following standards: UL 1004-1, the Standard for Safety of Rotating Electric Machines;
UL 1004-2, the Standard for Safety of Impedance Protected Motors; UL 1004-3, the Standard for Safety of Thermally Protected Motors; and UL 2111, Standard for Overheating Protection of Motors. 12
During the manufacturing process, electric motors endure a variety of tests to ensure proper operation and integrity. But for compliance testing, the UL thermal tests are the primary interest. For example, UL 2111 13 stipulates the following acceptable temperature rises for NEMA B electric motors:
- Locked Rotor: 225oC in the first hour; 200oC in the second hour.
- Full-load, heat run: 165oC
- Running overload: 165oC if protector opens; 175oC if protector doesn’t open.
Energy Efficiency Compliance
Since the passage of the 1992 Energy Policy Act (EPACT)14 that mandated full-load motor efficiencies, energy efficiency compliance has increased and influenced the introduction of energy efficient motors. For compliance, motor efficiency must be confirmed by a “test procedure acceptable to the U.S. Department of Energy” 15 and accomplished in an approved testing facility, such as UL. 16
(Note: D.C. motors are excluded from the EPACT legislation because “unlike an induction motor, a d-c machine inherently offers a range of operating speed, determined by field control settings, throughout which efficiency is a variable.”17
Electromagnetic compatibility (EMC) compliance has become a greater concern due to the increased use of power converters (D.C. drives) and inverters (A.C./D.C. drives) for industrial motor control, causing electromagnetic interference (EMI) with other equipment. It’s been known for a long time that switches, relays and brushed-commutator motors are sources of EMI18. But the high-switching frequencies of power converters and switched-mode power supplies has exacerbated the EMI problem.
EMI results from “electromagnetic radiation, [which] is a form of energy at a particular frequency that can propagate through a medium. This intentionally or unintentionally generated EM energy is considered electromagnetic interference (EMI) if it degrades the performance of electronic systems. Due to the increasing amount of man-made generated EMI around the globe, allowable limits as well as measurement techniques on RF noise/interference have been set at national and international levels. The Federal Communications Commission (FCC) and the Military are the two governing bodies in the U.S. setting standards on EMI.” 19 Globally, the IEC is setting the standards on electromagnetic compatibility. It publishes the IEC 61000 series of standards that deal with the EM environment and describe electromagnetic phenomena, including measurement and testing techniques, as well as guidelines on installation and mitigation.
“EMC is defined as the ability of equipment to function satisfactorily in its electromagnetic environment without introducing intolerable disturbances to anything in that environment.” 20 For electric motors and industrial contro1, the standards typically used for EMC compliance21 are:
- UL508, Industrial control equipment for the USA
- IEC 61010, Industrial and Lab equipment
- EN 50178, Power Equipment
- IEC 61000, Generic EMC standards
The CE Mark: Global Compliance
Globalization, world trade, free and open markets–all these words are synonymous with the nature and context of business today. American manufacturers (be it D.C. motors or washing machines) need to prepare their products so they can be sold in other parts of the world. Global certification and compliance is part of this preparation. For U.S. companies, the most common type of global safety compliance is the CE mark issued by the European Union. 22
In 1985, when it was first introduced, the CE mark was meant to encourage trade among the European Union’s member nations. But, in 1986, many imports into the EU experienced trade barriers due to “inconsistent national product requirements.” 23 This provided an additional impetus for the adoption of the CE mark.
The development of the CE marking system decreased these inconsistencies and created “a set of product safety standards and a series of conformity assessment procedures that are used to prove that these standards have been properly implemented.” Both China and Japan are developing compliance programs similar to the CE mark. For the U.S., gaining the CE mark compliance is critical since the EU is the “largest foreign market for the U.S.”24
The CE mark is not a quality certification; rather, it’s certification that indicates the product is in compliance with “the health and safety requirements of the directive that applies to the product.”25
Three EU directives related to the compliance of electric motors. They are:
- Machine Directive
- Electromagnetic Compatibility (EMC) Directive
- Low Voltage Directive
The Machine Directive focuses on fundamental health and safety requirements concerning the design and construction of machinery. The EMC Directive focuses on the requirements for EMI emissions and immunity. The Low Voltage Directive focuses on electrical, physical and mechanical product safety, including motor efficiency.
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