The person tasked with finding a replacement circuit breaker may not fully understand the importance of the relationship between the circuit breaker and the ATS it is protecting. IEEE 1584 Guide for Performing Arc Flash Hazard Calculations. You should consider contributing to our CFE Media editorial team and getting the recognition you and your company deserve. Chapter 5 Emergency Power Supply: Energy Sources, Converters, and Accessories. The ATS is manufactured, shipped, and installed at the job site. (EPSS ? The operator has the ability to determine when to initiate the load transfer, but the actual transfer operation is electrically actuated. When the primary source is restored and stabilized, the transfer switch transitions back to the primary source and resumes under normal operation. Curtis Power Solutions - NFPA 110 Transfer Switch Equipment You are using an out of date browser. ), Type of neutral (solid, switched, overlapping), Connection type (front/rear connect, mechanical/compression lugs). This enables transfer switch maintenance without shutting down equipment as well. First, the ATS must withstand a short circuit when the switch is in a closed position. When the primary source has been reestablished for a prescribed time to ensure stability, the switch may automatically transfer the load back to the primary source. This site uses cookies and other tracking technologies to assist with navigation, providing feedback, analyzing your use of our products and services, assisting with our promotional and marketing efforts, and provide content from third parties. These systems may include fire detection and alarm systems, elevators, fire pumps, and egress lighting. These same ATSs protected by appropriate fuses have a 200 kA WCR. During this process, there is a sustained duration of paralleled operation between the two sources. Hopefully this blog helped shed some light on the requirements and layout of the standard. These systems may include heating and refrigeration systems, communications systems, ventilation and smoke removal systems, and other processes that, when stopped in the event of primary source interruption, could create hazards or hamper rescue or firefighting operations. Finally, if proper maintenance is not performed, the trip characteristics of circuit breakers may change as they age. NFPA 70B Recommended Practice for Electrical Equipment Maintenance, NFPA 70E Standard for Electrical Safety in the Workplace, NFPA 110 Standard for Emergency and Standby Power Systems. NFPA 110 Standard for Emergency and Standby Power Systems. Chapter 6 of NFPA 110 contains performance requirements for transfer switches and their associated equipment. Level The level has to do with whether or not failure of the equipment could result in the loss of life or serious injury. Keeping ATS systems properly maintained through preventive and predictive maintenance will minimize overall O&M requirements, improve . Section 7.2.1 requires a separate room with a 2-hour fire-resistance rating (again for Level 1 systems) for EPS equipment. These systems provide an alternate source of electrical power in buildings when the normal electrical power source fails. Electrical operation and mechanical holding, Transfer and retransfer of the load automatically. A consulting engineer needs to specify the following for a hospital patient wing addition. When the connection to the secondary source is established, the primary source will disconnect. [. Although a specific breaker may be properly short-circuit combination rated with the ATS at the time of the initial installation, it is very likely that over the life of a system, the circuit breaker may need to be replaced. We help you measure, assess and improve your performance. In addition, NFPA 110 Standard for Emergency and Standby Power Supply Systems (NFPA 2019b) provides guidance on the frequency and testing for critical switchgear such as an ATS. It is mandatory to procure user consent prior to running these cookies on your website. ATS systems require preventive and predictive maintenance as well as regular testing to assure the highest reliability. Any cookies that may not be particularly necessary for the website to function and is used specifically to collect user personal data via analytics, ads, other embedded contents are termed as non-necessary cookies. Up until now i assumed that the transfer switch needed 3.5' in front to comply with NEC art. [, Instruction and equipment shall be provided for safe manual nonelectric transfer in the event the transfer switch malfunctions. This checklist does not supersede maintenance recommendations from the equipment manufacturer, nor is it a replacement for contracted O&M or warranty services. Transfer from the normal power source to the emergency source must complete within 10 seconds and meet the requirements of Article 700 of the National Electrical Code (NFPA 70). In addition to the ease in achieving ATS WCR of 200 kA because of their current-limiting ability, fuses are easy to achieve selective coordination, even for high fault currents. Quantity: Five automatic transfer bypass isolation switches, 600 A, 480 V, 4-pole switched neutral, with a NEMA 1 enclosure. Search Products And Discover New Innovations In Your Industry. That is the last thing i'm not clear on. [, 6.4.2.1.5.12* Indication of Switch Position, Two pilot lights with identification nameplates or other approved position indicators shall be provided to indicate the transfer switch position. As you can see in the second list, many factors define the protection level provided by a circuit breaker. Normally you wheel it outside an place it where exhaust fumes cannot seem into windows, doors or vents. Ryan Ishino is the associate director of electrical for the Orange County office at JBA Consulting Engineers in Irvine, Calif. Type U, which needs to be basically uninterruptiblesimilar to an uninterruptible power supply systemand a Type M, which has no time limit and can be manually activated. Automatic transfer switches, as well as delayed automatic, constantly monitor the source of normal power so, in the event of a power failure, the transfer switch moves the electrical load to the emergency power supply system. 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Eisenberg Patient Safety and Quality Award, Bernard J. Tyson National Award for Excellence in Pursuit of Healthcare Equity, Continuing Education Credit Information FAQs. In the past this option was thought to alleviate many of the procurement, installation, or replacement issues that occur when using the specific breaker option above. The generator is only for legally required standby power for the elevators. An alternative solution would be to use fuse protection. While in most cases the standard connection type for ATS installation is mechanical screw-type lugs, many projects request compression lugs for ATSs. The label is typically affixed on the inside door of the enclosure. UL 1008, Transfer Switch Equipment, is the product standard for ATSs. Legally required standby systems (NEC Article 701): Legally required standby systems are defined by the NFPA as "intended to automatically supply power to selected loads (other than those classed as emergency systems) in the event of failure of the normal source." Review our, NFPA 70-2014: National Electrical Code (NEC), NFPA 1600-2013: Standard on Disaster/Emergency Management and Business Continuity Programs, NFPA 99-2015: Health Care Facilities Code, UL 1008A-1: Standard for Medium-Voltage Transfer Switches, NFPA 110-2016: Standard for Emergency and Standby Power Systems, Your questions answered: Circuit protection in health care facilities, Coordinating protective devices in mission critical facilities, Complying with NFPA 110 in mission critical facilities, Power for emergency systems focus on value add, Navigating the route to more sustainable mission critical power. Requirements that fit one situation might not be appropriate for another situation. Certain issues may arise when specific breaker combinations are used. This situation is common across the industry. An adjustable time-delay device shall be provided to delay the load-transfer process to avoid excessive system voltage drop for use where the failure of operation of equipment could result in injury or loss of human life. The purpose of the test is to allow an ATS to be marked for use with any manufacturers circuit breaker that incorporates an instantaneous trip when the ATS and circuit breaker are applied within their ratings. Inspect the exterior and interior of enclosure; look for signs of heat stress or moisture/pervious wetness. However, some AHJs may require separate transfer switches for loads dictated by NEC Articles 700 and 701 for complete segregation of systems; the AHJ should be consulted for acceptable and approved system configurations. NFPA 7.2.2.1 does not clearly state if it applies to Level 1 or Level 2 or both? I cannot find any article in the NEC that talks about where to mount or clearances for transfer switches. Emergency systems (NEC Article 700): Emergency systems are defined by the NFPA as "intended to automatically supply illumination, power, or both, to designated areas and equipment in the event of failure of the normal supply or in the event of accident to elements of a system intended to supply, distribute, and control power and illumination essential for safety to human life." This can be done through a variety of means that are categorized into two groups: rotating equipment (generators) and fuel cells. These circuit breakers increase the time that an ATS must withstand a short-circuit current. Because the ATS is connected to both primary and backup power, it serves as an intermediary between the load and the sources of power. Standby power systems have many components, including transfer switches that must be designed correctly. Consulting engineers must understand transfer switch types, timing requirements, ratings, and the types of standby systems where transfer switches are used to transfer to backup power. ), ATS manufacturer (ASCO, Russelectric, Zenith, Cummins, Caterpillar, Eaton, Kohler, etc. Represents the most recent date that the FAQ was reviewed (e.g. Through leading practices, unmatched knowledge and expertise, we help organizations across the continuum of care lead the way to zero harm. The basis of this article is NFPA 70-2014: National Electrical Code (NEC) unless otherwise noted. and ?normal,? Fast closed-transition transfer switches: Fast closed-transition transfer switches use a momentary paralleling of sources (typically less than 100 msec) using a control system similar to the open-transition transfer switch system. What is the voltage to ground, etc? This transition can occur automatically or manually. 1. Best Practices for Automatic Transfer Switches Operation and Find out about the current National Patient Safety Goals (NPSGs) for specific programs. Another commonly overlooked design concern is the connection type chosen for the ATS. When designing a power system and specifying an ATS, two important design considerations must be evaluated: An ATSs withstand and closing (close on) rating (WCR), and how the overcurrent protective device (OCPD) protecting the ATS affects system selective coordination. Businesses like hotels, schools, construction . Acceptance testing is required in order to confirm that the system will perform as required. Again, this will require the move up to an even larger ATS. Types of changes and an explanation of change type: This standard applies to automatic, manual or nonautomatic, closed transition, hybrid, fire pump transfer switches, bypass/isolation switches, and several others. An ATS is often used with standby power systems that serve critical loads such as industrial processes, data networks, and other installations such as health care, financial, and military applications. Actions and activities recommended in this Best Practice should only be attempted by trained and certified personnel. Find evidence-based sources on preventing infections in clinical settings. The secondary source typically consists of the backup or emergency power source. NFPA 110 addresses performance requirements for emergency and standby power systems. This enables a continuous source of supply to the electrical system as the two sources are paralleled together. Performance monitoring of an ATS is typically carried out as part of normal O&M activities with documentation. All related code and safety procedures must be understood and followed. This, however, has changed with the advancement and growing understanding of selective coordination. Any examples are for illustrative purposes only. JavaScript is disabled. Proper emergency system design requires full understanding of the relationship between a transfer switch and the systems overcurrent protection. Practical example: If the circuit breaker protecting the ATS has an intentional short time delay of 0.1 seconds (6 cycles), a 3-cycle any breaker rating will not provide adequate protection for the ATS. Switches to generator power immediately, while a manual switch would need to be flipped manually. 5. We also use third-party cookies that help us analyze and understand how you use this website. You also have the option to opt-out of these cookies. The transfer is the process of shifting load from the secondary or alternate source, and vice versa. These cookies do not store any personal information. Out of these, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities of the website. A successful ATS maintenance program will follow the manufacturers equipment guidelines, actions, and frequencies for all maintenance activities. Transfer equipment, including transfer switches, are required to be automatic, identified for emergency use, and approved by the authority having jurisdiction (AHJ). The options available for ATSs with short time ratings are limited and also usually carry a higher price tag when compared to ATSs with standard WCRs. However, these functions can increase the costs significantly and usually require a higher level of technical operations personnel to maintain them over their lifetime. National Fire Protection Association, Quincy, MA. An automatic transfer switch is especially helpful if you can't afford any delay in regaining power. For more information and training on NFPA 110, check out our, National Fire Protection Association (NFPA) 2022, The value of Standards Development Organizations, Alternative Fuel Vehicles Safety Training, Certification for Electrical Safety in the Workplace, Safety in living and entertainment spaces. 4. Lets look at a common ATS example. They can be classified as an automatic transfer switch, a delayed automatic transfer switch, or a manual transfer switch, depending on the load being served and the required type of emergency power supply system. Chapter 8 Routine Maintenance and Operational Testing. To view the list of specific breakers tested and accepted, contact the ATS manufacturer. But opting out of some of these cookies may affect your browsing experience. requirements of the following standards and codes (latest edition): A. UL 1008 - Standard for Automatic Transfer Switches . This may include personalization of content and ads, and traffic analytics. 2019a. NEC (700, 701, 708) requirements Generator start contacts (Form C) provide means to comply with 695.14(F) and 700.10(D)(3) of the Manual: In manual mode, the entire process is completed manually by an operator. x 60 in. 624 0 obj <> endobj These include power sources, transfer equipment, controls, supervisory equipment, and accessory equipment needed to supply electrical power to the selected circuits. Learn more about the communities and organizations we serve. [, 6.4.2.1.5.8 Time Delay Bypass if EPS Fails, The time delay shall be automatically bypassed if the EPS fails. Regardless of the type of fuel, it needs to be sized to 133 percent of the fuel required to run the generator for the time required by the class of the system. Automatic transfer switches (ATSs) are a vital part of many life safety and mission critical systems where continuity of service is crucial. This means that the transfer switch disconnects from the primary source before establishing the connection to the secondary source (see Figure 2). Do you have experience and expertise with the topics mentioned in this content? Automatic transfer switch protection | Consulting - Specifying Engineer Due to the criticality of the ATS to the larger standby/emergency generation system, tracking and trending of any preventive and predictive maintenance findings is critical to a high-reliability system. Transfer switch locations are not addressed within the, Here is a link to the ROP 8 for proposals on this issue. Paralleling switchgear is typically used to combine multiple power sources (commonly two or more generators) and connect to a common bus to use the aggregate capacity of the sources (see Figure 4). [, A time-delay device shall not be required, provided it is included with the engine control panel, or if a utility feeder is used as an EPS. UL 1008 Transfer Switch Equipment. Specific breaker combinations are often highly scrutinized by the authority having jurisdiction (AHJ) during an inspection. Describe types of standby systems and transfer switch requirements. [, 6.4.2.1.5.5 Time Delay at Engine Control Panel, Time delays shall be permitted to be located at the engine control panel in lieu of in the transfer switches. If current limiting fuses are specified upstream of the ATS, the energy let through during a fault will be far below the withstand threshold of the ATS, allowing the original 600 A ($15,000) ATS to be protected from any fault up to 200 kA. Transfer mechanismthis device switches the facility and load circuits to and from the utility (normal) or the standby power source (emergency). of codes and abbreviations avoid potential confusion, and refined data . The Operating Principles of an Automatic Transfer Switch annual review). https://www.shopulstandards.com/ProductDetail.aspx?productId=UL1008_8_B_20141222(ULStandards2). [, The minimum 5-minute delay shall not be required on small (15 kW or less) air-cooled prime movers. Automatic transfer switches (ATSs) are a vital part of many life safety and mission critical systems where continuity of service is crucial. The failure of one or more of these subsystems could compromise the ability of the emergency power system to deliver electricity in an emergency. | Figure 3 is a WCR table for all the ampere ratings for a manufacturers specific ATS series. PDF Transfer switch 101 - Eaton Chapter 4 Classification of Emergency Power Supply Systems. Likewise, diminished protection ratings or significant and unnecessary costs and size implications for the ATS may be introduced to a design. PDF ATS controllers and remote annunciators What is an Automatic Transfer Switch? - Power Plus Compare types of transfer switches and their operations. This would be useful during the specification/procurement process. hb```G@9B7$p$&<0c~|vjRFe~&| &4:09 @v$A1& #| +6c0e-lFmL@X=@A ne*FW L Additional electrical room floor space required = 20 in. An automatic transfer switch (ATS) is a device that allows safe transfer of electricity from a primary source, usually an electric-utility grid, to a backup source such as an emergency or standby generator. Out of these, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities of the website. UL. For instance, an ATS when designed as a rear connect switch is rated for 65 kA WCR with instantaneous trip circuit breaker protection, but it may have only a 50 kA WCR if the front connect version is chosen. For this reason, the rating was referred to as the any breaker rating and was considered the best practice solution when using circuit breakers for ATS protection. There are three functional components of a typical ATS: Only qualified and experienced personnel should work with an ATS. Visual annunciation when not in automatic mode. Common configurations will actually afford an ATS with a lower WCR in certain cases. automatic transfer switches shall supply only the fire alarm system and other systems specifically permitted by the New York City Construction Codes, New .