Multiple safeguards apply to power supplies used in industrial automation. Individually, these safeguards apply to different areas of operation; collectively, they supplement each other to provide appropriate levels of protection, preventing accidents, equipment damage, and injuries.
Learn about the many safety standards governing power supplies in industrial automation
Nov 15, 2024
In industrial automation systems, the safety of both loads (equipment and machinery) and personnel is paramount. Power supplies are a crucial component of these systems, of course. However, they also pose potential risks if not properly managed. In this blog we’ll discuss the safety requirements for equipment and personnel as they relate to power supplies in an industrial setting.
Table of contents
What are safety classes, zones, and divisions?
Providing the appropriate level of protection requires precisely defining different aspects of the industrial environment and the levels of risk associated with it. Several protection classifications cover different areas of operation.
Safety Classes (I, II, III) define protection levels against electric shock. Class I equipment must be grounded; Class II features double insulation; and Class III operates at a voltage low enough to avoid the risk of electric shock.
Hazardous Locations are categorized by the Class and Division system (North America) or Zone system (International), indicating the presence of flammable gases, vapors, or dust.
Temperature Classes (T1 to T6) denote maximum safe surface temperatures, and Ingress Protection (IP) Ratings specify protection against dust and water, ensuring equipment can withstand environmental conditions.
Protection ratings for enclosures
The enclosures that house the power supplies are assessed according to the location where they are used.
ATEX (ATmosphères EXplosibles) is a European standard focusing on equipment used in potentially explosive atmospheres based on their Zone rating. ATEX enclosures are designed to prevent ignition of these atmospheres and include explosion-proof features and flame arresters. The standard emphasizes preventing equipment from causing sparks or excessive heat that could ignite explosive materials.
IEC Ex is an international certification system for equipment used in explosive atmospheres, providing a global standard for safety. It harmonizes the approach to certification across various countries, ensuring equipment meets stringent safety requirements to prevent explosions. IEC Ex covers a broad range of hazardous environments and emphasizes international consistency in testing and certification.
NEMA (National Electrical Manufacturers Association): NEMA enclosures are primarily used in North America and focus on protecting equipment from environmental factors like dust, moisture, and extreme temperatures rather than explosive atmospheres. NEMA ratings range from NEMA 1 (general-purpose protection) to NEMA 13 (severe conditions requiring waterproof and dustproof capability).
Safety standards for industrial power supplies
Three important safety standards that govern industrial power supplies are UL 60947, EN/IEC 61010-2-201, and EN/IEC UL 62368-1. Most RECOM AC/DC and DC/DC power supplies meet one or more of these standards.
UL 60947 is a safety standard for industrial control equipment, including industrial power supplies, established by Underwriters Laboratories (UL). It outlines requirements for electrical, mechanical, and fire safety to ensure the safe operation of power supplies used in industrial control systems. UL 60947 covers aspects such as overcurrent protection, insulation, temperature ratings, and environmental resistance, ensuring that power supplies can withstand the rigors of industrial environments. Compliance with UL 60947 indicates that a power supply has been tested for safety and reliability, providing assurance that it meets the necessary standards for protecting equipment and personnel in industrial applications.
IEC 62368-1 is a safety standard for audio, video, information, and communication technology equipment, including industrial power supplies. Unlike previous incident-based standards, EN/IEC 62368-1 uses a hazard-based approach to identify and mitigate potential risks such as electric shock, fire, and thermal injury by classifying energy sources based on their potential to cause harm, prescribing safeguards against those energy sources, and providing guidance on the application of, and requirements for, those safeguards. For industrial power supplies, this standard ensures adequate protection against these hazards by specifying requirements for insulation, overcurrent protection, temperature control, and mechanical stability. IEC 62368-1 replaces older standards such as EN 60950-1 (Information technology equipment) and EN 60065 (Audio, video and similar electronic apparatus). The standard includes all products that were previously covered under the older standards, plus others.
IEC 61010-2-201 sets safety requirements for control equipment, including industrial power supplies, used in measurement, control, and laboratory applications. Key aspects include electrical safety (insulation, creepage distances, and shock protection), thermal management (overtemperature protection and temperature rise limits), and mechanical safety (enclosure strength and accessibility of parts). The standard also covers environmental protection (resistance to dust, moisture, and corrosive substances) and functional safety (reliable control functions and redundancy). Compliance ensures power supplies are safe and reliable for industrial environments, preventing equipment damage and protecting personnel from electrical hazards.
How do these last two standards differ? IEC 62368-1 is broader in scope, while IEC 61010-2-201 is more specific to industrial settings. IEC 62368-1 focuses on a hazard-based safety engineering approach for a broad range of electronic equipment, including consumer and office environments. It emphasizes protecting against potential harm based on energy classification and is suitable for general use.
In contrast, IEC 61010-2-201 provides detailed safety requirements specifically for industrial control equipment, including industrial power supplies. It is tailored to industrial environments, focusing on electrical, mechanical, and environmental durability, and assumes trained users in more hazardous conditions.
In contrast, IEC 61010-2-201 provides detailed safety requirements specifically for industrial control equipment, including industrial power supplies. It is tailored to industrial environments, focusing on electrical, mechanical, and environmental durability, and assumes trained users in more hazardous conditions.
What is LPS certification and why is it important?
LPS stands for Limited Power Source. An LPS certified power supply is designed to meet specific safety requirements to limit the risk of electrical shock or fire. These power supplies are regulated by standards such as IEC 62368-112.
Key characteristics of LPS certified power supplies include:
These limitations ensure that LPS certified power supplies are highly unlikely to cause electrocution or fire, making them safer for use in various applications.
RECOM’s RACM90-K AC/DC power supply series provides 90W output and is LPS-rated according to safety standards for medical, ITE, industrial and household markets. With an industry-standard 2”x4” footprint, variants are available as an open card or with an enclosure. The wide-range input encompasses 100VAC to 240VAC, and the output is tightly regulated. Easy system integration is enabled by a wide compliance margin to EMC standard EN55032 class B. On-board dual fuses are included, and the family includes immunity to surges for installation class 3 and over-voltage category OVCIII. Certifications are maintained to 4000m altitude and with a wide operating temperature range, the series is one of the most versatile on the market.
Key characteristics of LPS certified power supplies include:
- Voltage and Current Limits. LPS certification imposes strict limits on output voltage and current. For example, the output voltage is typically less than or equal to 30VDC or 30VACrms, and the maximum short circuit current is limited to 8A.
- Power Limits. The maximum power output is limited to 100W, even under fault conditions.
- Safety Features. LPC supplies often include overcurrent protection devices like fuses or circuit breakers to limit the current supplied to the load.
These limitations ensure that LPS certified power supplies are highly unlikely to cause electrocution or fire, making them safer for use in various applications.
RECOM’s RACM90-K AC/DC power supply series provides 90W output and is LPS-rated according to safety standards for medical, ITE, industrial and household markets. With an industry-standard 2”x4” footprint, variants are available as an open card or with an enclosure. The wide-range input encompasses 100VAC to 240VAC, and the output is tightly regulated. Easy system integration is enabled by a wide compliance margin to EMC standard EN55032 class B. On-board dual fuses are included, and the family includes immunity to surges for installation class 3 and over-voltage category OVCIII. Certifications are maintained to 4000m altitude and with a wide operating temperature range, the series is one of the most versatile on the market.
Conclusion
Ensuring safety for both equipment and personnel in industrial automation is a complex and multi-faceted task. Multiple safety standards cover the power supplies themselves, the enclosures that house them, and the environment in which they operate. All RECOM power supplies comply with the relevant standards. RECOM’s RACM90-K family is LPS-certified and features multiple other safety ratings required for the most stringent medical and industrial applications.
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