IEEE Guide for Substation Fire Protection PDF

IEEE Guide for Substation Fire Protection IMPORTANT NOTICE: IEEE Standards documents are not intended to ensure safety, health, or environmental protection, or ensure against interference with or from other devices or networks. Implementers of IEEE Standards documents are responsible for determinin...

IEEE Guide for Substation Fire Protection IMPORTANT NOTICE: IEEE Standards documents are not intended to ensure safety, health, or environmental protection, or ensure against interference with or from other devices or networks. Implementers of IEEE Standards documents are responsible for determining and complying with all appropriate safety, security, environmental, health, and interference protection practices and all applicable laws and regulations. This IEEE document is made available for use subject to important notices and legal disclaimers. These notices and disclaimers appear in all publications containing this document and may be found under the heading “Important Notice” or “Important Notices and Disclaimers Concerning IEEE Documents.” They can also be obtained on request from IEEE or viewed at http://standards.ieee.org/IPR/disclaimers.html. 1. Overview 1.1 Scope The original guide (1994) was developed to identify substation fire protection practices that generally have been accepted by industry. This revision includes changes in industry practices for substation fire protection. New clauses on fire hazard assessment and pre-fire planning have been added. 1.2 Purpose The purpose of the original guide (1994) was to give design guidance, fire hazard assessment, and pre-fire planning in the area of fire protection to substation engineers. Existing fire protection standards, guides, and so on that may aid in the design of specific substations or substation components are listed in Annex F. This revision updates that guidance. 1.3 General The guide outlines substation fire protection practices based on industry standards and good practices. It incorporates lessons learned from substation fires, substation fire protection research and testing, advancements in fire protection engineering practices, and changes in fire protection due to risk and 1 Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: Queen's University. Downloaded on August 25,2014 at 10:41:09 UTC from IEEE Xplore. Restrictions apply.  IEEE Std 979-2012 IEEE Guide for Substation Fire Protection environmental concerns. The guide provides design guidance in the area of fire protection for substation engineers and others involved in substation fire safety and protection. The predominant dielectric insulating fluid for transformers is mineral oil, and mineral oil constitutes one of the primary fire hazards in the substation. Consequently, much of this guide addresses hazards and protection measures based on mineral oil fires. There are several alternative fluids with improved fire safety properties (higher flash and fire points), known as “less-flammable” dielectric fluids, which have been introduced. Many of these fluids have been recognized as reducing the hazard and the risk of a fire occurring relative to mineral oil. Use of a “less flammable” fluid is one means to reduce the risk of fire at a substation. See 8.4.2 and A.21 for additional information on these fluids. It is the intent of this guide that the analysis and decisions made may require the use of a team approach comprising various specialists. These specialists will be able to provide specific guidance on their areas of expertise; provide interpretation of the related codes, standards, and practices; and help formulate fire protection solutions. The following are some of the specialists that could be involved: ⎯ Substation design engineers (civil, electrical, mechanical, and structural) ⎯ Substation operation and maintenance staff ⎯ Fire protection engineers and specialists ⎯ The local fire department ⎯ The authority having jurisdiction over the substation ⎯ Architects and code consultants This guide provides fire protection guidance for the following types of substations that have the principal power delivery functions accomplished with alternating current (ac) or direct current (dc) power and are operated at voltages of 1 kV and above: ⎯ Generating plant switchyards ⎯ Customer substations ⎯ Switching substations ⎯ Transmission substations ⎯ Distribution substations ⎯ Capacitor substations ⎯ Converter station switchyards The types of substations listed can be designed in a number of different configurations and layouts as follows: ⎯ Outdoor substations ⎯ Indoor substations ⎯ Multistory above-grade substations ⎯ Multistory below-grade substations ⎯ Substations in mixed-use buildings including high-rise (>22.9 m) buildings ⎯ Substations in conjunction with other related operations (e.g., offices, maintenance facilities, and control centers) 2 Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: Queen's University. Downloaded on August 25,2014 at 10:41:09 UTC from IEEE Xplore. Restrictions apply.  IEEE Std 979-2012 IEEE Guide for Substation Fire Protection This guide provides electric power engineers and fire protection professionals with fire protection and safety guidelines for application in the planning, design, and operation of substations. Guidelines are outlined in the following critical areas of application: ⎯ The identification of substation fire hazards ⎯ The fire protection aspects for substation sites, buildings, and switchyards ⎯ Issues to be considered when selecting the various types and levels of fire protection ⎯ Recommended typical fire protection applications ⎯ Fire planning and incident management This guide is not intended to be the primary standard for the minimum levels of fire protection required for new and existing substations. The minimum required level of substation fire safety and protection is based on the minimum requirements of governing authorities and on the level of risk the asset owner is willing to accept. This guide provides design options and strategies for the mitigation of substation fire hazards once the minimum required level of substation fire safety and protection is determined. The application of this guide is not meant to take precedence over local building, fire, safety, and electrical codes. It is intended to be used in conjunction with these governing codes and standards for the purpose of providing specialized substation fire protection guidance for asset protection and customer service reliability. This document does not necessarily cover aspects of life safety covered by local building, fire, safety, and electrical codes. Refer to A.1 for additional information. 2. Normative references The following referenced documents are indispensable for the application of this document (i.e., they must be understood and used, so each referenced document is cited in text and its relationship to this document is explained). For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments or corrigenda) applies. IEEE Std 980TM, IEEE Guide for Containment and Control of Oil Spills in Substations.1, 2 NFPA 850, Recommended Practice for Fire Protection for Electric Generating Plants and High Voltage Direct Current Converter Stations.3 NFPA 851, Recommended Practice for Fire Protection for Hydroelectric Generating Plants. When exploring the additional information in NFPA 850 and NFPA 851, keep in mind that these documents were developed for generating facilities that have different hazards and risks than transmission and distribution substations. 3. Definitions For the purposes of this document, the following terms and definitions apply. The IEEE Standards Dictionary Online should be consulted for terms not defined in this clause.4 1 The IEEE standards or products referred to in this clause are trademarks of The Institute of Electrical and Electronics Engineers, Inc. 2 IEEE publications are available from The Institute of Electrical and Electronics Engineers (http://standards.ieee.org/). 3 NFPA publications are available from the National Fire Protection Association (http://www.nfpa.org/). 3 Authorized licensed use limited to: Queen's University. CopyrightDownloaded on August © 2012 IEEE. 25,2014 All rights at 10:41:09 UTC from IEEE Xplore. Restrictions apply. reserved.  IEEE Std 979-2012 IEEE Guide for Substation Fire Protection 3.1 General terms control building: A building or structure in a substation that contains protection, control, system control and data acquisition (SCADA), and telecommunications equipment, electrical panels, battery banks, and other auxiliary equipment. In this guide, this term may be used interchangeably with other commonly used terms such as control house or control enclosure. fire protection: The study and application of measures to prevent, detect, extinguish, control, or deal with fires, and the subsequent impact on people, assets, business activities, or the environment. hazard: Any source of potential damage, harm, or adverse health effects on something or someone under certain conditions at work. risk: The chance or probability that a person will be harmed or experience an adverse health effect if exposed to a hazard. It may also apply to situations with property or equipment loss. switchyard: The outdoor portion of a substation with only a single voltage level. In multivoltage substations, the switchyards are typically connected by one or more power transformers. 3.2 Fire-suppression system terms clean agent gas fire extinguishing systems: A fire protection system that uses clean gaseous agents that are (1) electrically nonconducting, (2) volatile or gaseous, and (3) do not leave a residue on evaporation. The system discharges the agent for the purpose of achieving a specified minimum agent concentration throughout a hazard volume. A clean agent complies with restrictions on the production of certain Halon fire extinguishing agents under the Montreal Protocol signed September 16, 1987. deluge sprinkler system: A sprinkler system employing open sprinklers that are attached to a piping system that is connected to a water supply through a valve that is opened by the operation of a detection system installed in the same areas as the sprinklers. When this valve opens, water flows into the piping system and discharges from all sprinklers attached thereto. double interlock preaction sprinkler system: A Preaction system that admits water to sprinkler piping on operation of both detection devices and automatic sprinklers and only discharges from opened sprinklers. This type of arrangement provides the most redundancy to reduce the probability of accidental sprinkler discharge by requiring both detection devices and sprinklers to activate independently prior to water being admitted to the piping network. This type of arrangement also allows for pressure monitoring to detect leaks in the piping network or open sprinklers prior to water being admitted to the system. dry pipe sprinkler system: A system employing automatic sprinklers that are attached to a piping system containing air or nitrogen under pressure, the release of which (as from the opening of a sprinkler) permits the water pressure to open a valve known as a dry pipe valve, and the water then flows into the piping system and out the opened sprinklers. foam-water system: A sprinkler system that generates a foam-water solution and discharges it onto the hazard to be protected utilizing air-aspirating foam-water sprinklers or nozzles or non–air-aspirating standard sprinklers. overhead sprinkler system: The installation includes at least one automatic water supply that supplies one or more systems. The portion of the sprinkler system above ground is a network of specially sized or hydraulically designed piping installed in a building, structure, or area, generally overhead, and to which 4 The IEEE Standards Dictionary Online subscription is available at http://www.ieee.org/portal/innovate/products/standard/ standards_dictionary.html. 4 Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: Queen's University. Downloaded on August 25,2014 at 10:41:09 UTC from IEEE Xplore. Restrictions apply.  IEEE Std 979-2012 IEEE Guide for Substation Fire Protection sprinklers are attached in a systematic pattern. Each system has a control valve located in the system riser or its supply piping. Each sprinkler system includes a device for actuating an alarm when the system is in operation. The installation includes at least one automatic water supply that supplies one or more systems. The system is usually activated by heat from a fire and discharges water over the fire area. single interlock preaction sprinkler system: A single interlock system is a Preaction system that admits water-to-sprinkler piping upon operation of detection devices and discharges out only the opened sprinklers. This type of arrangement reduces the probability of accidental sprinkler discharge by requiring the activation of a detection device prior to admitting water to the sprinkler piping and then requiring a sprinkler head to open prior to water flow. water mist system: A distribution system connected to a water supply or water and atomizing media supplies that is equipped with one or more nozzles capable of delivering water mist intended to control, suppress, or extinguish fires. Water mist systems must only be used for applications that they are listed for or where specific research and testing has validated the application. water-oscillating monitor: Typically a supplement to an overhead sprinkler or foam system, they provide additional delivery of the liquid suppression agent to areas shadowed from the overhead sprinkler system. wet pipe sprinkler system: A sprinkler system utilizing automatic sprinklers attached to a piping system containing water and connected to a water supply so that water discharges immediately from sprinklers opened by heat from a fire. video image detection: The principle of using automatic analysis of real-time video images to detect the presence of smoke or flame. 3.3 Fire detection system terms beam detector: A type of photoelectric light obscuration smoke detector where the beam spans the protected area. dry-pilot line detector: A system of heat detection employing automatic sprinklers on a pressurized dry pipe network. The activation of a sprinkler causes a loss in system pressure, which is annunciated as an alarm signal. electronic heat detector: A fire detector that detects either an abnormally high temperature or a rate of temperature rise or both. linear heat detector: A heat-sensitive cable that has a fixed alarm temperature rating or a heat-sensitive cable in which the impedance with changes in temperature can be adjusted to specific resistance levels to establish alarm temperature thresholds. optical flame detector (IR3): A flame detection device sensitive to various portions of the infrared spectrum commonly emitted from flaming fires. This type of fire detection is not sensitive to smoldering fires, and detection is limited to each sensor’s field of view. pneumatic rate-of-rise heat detector: A line-type detector comprising small-diameter tubing, usually copper, which is installed throughout the protected area. The tubing is terminated in a detector unit containing diaphragms and associated contacts set to actuate at a predetermined pressure. The system is sealed except for calibrated vents that compensate for normal changes in temperature. 5 Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: Queen's University. Downloaded on August 25,2014 at 10:41:09 UTC from IEEE Xplore. Restrictions apply.  IEEE Std 979-2012 IEEE Guide for Substation Fire Protection smoke aspirating system: The principle of using an air sample drawn from the protected area into a high- humidity chamber combined with a lowering of chamber pressure to create an environment in which the resultant moisture in the air condenses on any smoke particles present, forming a cloud. The cloud density is measured by a photoelectric principle. The density signal is processed and used to convey an alarm condition when it meets preset criteria. spot-type ionization detector: The principle of using a small amount of radioactive material to ionize the air between two differentially charged electrodes to sense the presence of smoke particles. Smoke particles entering the ionization volume decrease the conductance of the air by reducing ion mobility. The reduced conductance signal is processed and used to convey an alarm condition when it meets preset criteria. This type of smoke detection is best applied to flaming or incipient fires in which small particulate matter is produced. spot-type photoelectric detector: The principle of using a light source and a photosensitive sensor onto which the principal portion of the source emissions is focused. When smoke particles enter the light path, some of the light is scattered and some is absorbed, thereby reducing the light reaching the receiving sensor. The light reduction signal is processed and used to convey an alarm condition when it meets preset criteria. This type of smoke detection is best applied to fires in which larger particulate matter is produced. wet-pilot line detector: A system of heat detection employing automatic sprinklers on a pressurized wet pipe network. The activation of a sprinkler causes a loss in system pressure, which is annunciated as an alarm signal. 4. Fire hazards 4.1 General The impact of fire hazards on health, safety, continuity of operations, and asset preservation is a reason to provide fire prevention, fire protection, and other fire safety measures. Fire hazards are the conditions that create the potential for a fire. Fire hazards have at least the following attributes: ⎯ The magnitude of a possible fire ⎯ The consequence of the potential loss ⎯ The probability of an occurrence over a period of time (i.e., risk) Subclauses 4.2 through 4.7 present recognized fire hazards found in substations. Refer to A.2 for additional information. 4.2 Combustible oil hazards Based on mass and potential for energy release, mineral-oil-insulated equipment is normally the largest fuel source present in most substations. Mineral-oil-insulated equipment includes the following: a) Transformers and reactors 1) Main tanks 2) Bushings 3) Radiators Authorized licensed use limited to: Queen's University. Downloaded on 6 August 25,2014 at 10:41:09 UTC from IEEE Xplore. Restrictions apply. Copyright © 2012 IEEE. All rights reserved.  IEEE Std 979-2012 IEEE Guide for Substation Fire Protection 4) Conservator tanks 5) Tap changers 6) Cooling pumps b) Instrument transformers c) Voltage regulators d) Circuit breakers e) Cables 1) Oil insulated 2) Pipe type 3) Potheads 4) Transition joints f) Capacitors g) Lubricating oil systems (e.g., for synchronous condensers) h) Oil pump houses i) Oil processing plants 4.3 Flammable and combustible liquid and gas hazards Other equipment-related fuel sources that may be found at substations include the following: a) Hydrogen-cooled synchronous condensers b) Oxy-acetylene used for maintenance and construction purposes c) Battery rooms 1) Heat from short circuits or thermal runaway 2) Hydrogen gas generated by battery charging d) Diesel- or propane-fueled generators and fuel cells for backup power e) Propane heating fuels f) Flammable and combustible liquid storage, handling, and dispensing 4.4 Fire exposure hazards Critical substation equipment and other assets can be compromised due to external fire exposures in addition to internal failure modes. Some example of exposure hazards include the following: a) Auxiliary structures 1) Office areas 2) Warehouse areas 3) Oil storage areas 4) Shop areas 7 Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: Queen's University. Downloaded on August 25,2014 at 10:41:09 UTC from IEEE Xplore. Restrictions apply.  IEEE Std 979-2012 IEEE Guide for Substation Fire Protection 5) Stand-by diesel generator buildings 6) Hazardous materials storage areas b) Any building, room, or support structure that is of combustible construction c) Miscellaneous combustible storage d) Vegetation (nearby forests, hedges, and shrubs). 4.5 Indoor substation hazards Indoor substations present a unique set of hazards requiring a higher level of fire protection for the following reasons: ⎯ Any smoke and other products of combustion contained in the building can create an exposure hazard to building occupants, emergency personnel, and possibly a corrosive exposure to critical substation equipment. ⎯ Heat (flame impingement, radiative and convective exposures) and the blast pressures from fires and explosions contained within the structure can expose the structure and/or equipment to damage. ⎯ The egress of building occupants and access by emergency personnel for manual firefighting and rescue operations can be complicated by the smoke, heat, structural damage, and travel distances. 4.6 Critical loss assets The following are critical elements of a substation that if destroyed or damaged can impact the substation’s ability to function: a) Control, computer, protection, switchgear rooms, and equipment 1) System protection equipment 2) Communication equipment 3) SCADA equipment 4) Computers b) Cable spreading areas, cable trenches, cable tunnels, and cable vaults c) Batteries and charger systems d) Station service transformers (dry or liquid filled) e) Power transformers f) Circuit breakers g) Bus structures h) Auxiliary equipment The annexes provide more information on fire hazards and their potential impacts. 8 Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: Queen's University. Downloaded on August 25,2014 at 10:41:09 UTC from IEEE Xplore. Restrictions apply.  IEEE Std 979-2012 IEEE Guide for Substation Fire Protection 4.7 Maintenance and construction Maintenance and construction activities can create high-risk conditions within substations. The following equipment and activities could present hazardous conditions: a) Oil-processing equipment b) Mobile transformers c) Painting d) Hot work (cutting, grinding, and welding) e) Maintenance activities f) Increased fire exposure and fuel load associated with 1) Temporary or permanent construction 2) Combustibles and flammable transient fire loads (e.g., fuel cans, rags, and wood) 3) Material and equipment storage 4) Office trailers 5) Parked vehicles 5. Fire protection considerations for substation sites 5.1 General The following should be considered during new site selection or existing site analysis: ⎯ External exposures ⎯ Site grades ⎯ Available firefighting water supplies ⎯ Emergency access to the substation ⎯ Fire emergency response capability ⎯ Prevailing winds ⎯ Environmental consideration Refer to A.3 for additional information. 5.2 External exposures External exposures are fire hazards external to the substation. A fire involving these external hazards has the potential to impact substation operations adversely and may spread into the substation with more significant consequences. A review of site fire exposures should consider all of the following: ⎯ Type of exposure and possible spread mechanisms ⎯ Level of existing protection present in the external exposure Authorized licensed use limited to: Queen's University. Downloaded on August 25,2014 at 10:41:09 UTC from IEEE Xplore. Restrictions apply. 9 Copyright © 2012 IEEE. All rights reserved.  IEEE Std 979-2012 IEEE Guide for Substation Fire Protection ⎯ Risks involved ⎯ Additional fire protection features required to create an acceptable level of risk Subclauses 5.2.1 through 5.2.3 discuss some typical external hazards. ANSI/NFPA 80A-2012 [B30]5 provides a method for the analysis and mitigation of external radiant heat threats from these types of exposures. 5.2.1 Forested or grassland areas Forest and grass fires can expose the substation to conductive smoke, fire plumes, radiant heat, and soot. Generally, unplanned landscaping, trees, and vegetation should be removed for a minimum of 9.1 m (30 ft) beyond critical buildings, structures, and equipment. In addition, vertical vegetation (i.e., trees) heights should be analyzed to minimize fall potentials that exist within 9.1 m (30 ft) of operational critical buildings and equipment. Refer to A.4 for additional information. 5.2.2 Hazardous industries or operations Chemical plants, petroleum refineries, liquefied natural gas plants, and compressed gas tank farms are examples of neighboring facilities that could pose an external threat to substation operations should an emergency or fire occur at the neighboring site. Spatial separation or other fire protection methods should be used to protect the substation from these types of external threats. 5.2.3 Combustible buildings Nearby combustible buildings and warehouses often represent substantial fuel loads that can expose the substation to conductive smoke, fire plumes, radiant heat, and soot. Spatial separation or other fire protection methods should be used to protect the substation from these types of external threats. Refer to 7.2.4 for additional information and other reference documents such as ANSI/NFPA 80A-2012 [B30]. Temporary enclosures made of combustible materials and temporary heating for construction activities require special considerations for fire prevention. Issues include providing safe heating sources and isolation of combustible materials from hot work. Wherever possible, buildings used to support the operation of a substation (e.g., offices and warehouses) should be located outside the substation fence. 5.3 Site grading Mineral oil spill fires can spread long distances over a wide area, potentially exposing critical elements of the substation to fire. In addition, oil can cause environmental impacts if it reaches nearby environmentally sensitive areas such as streams and rivers or is absorbed into the ground. One of the most critical factors that can impact the fire protection of substation equipment and buildings is the site grading. Special attention should be paid to site grading conditions, spatial separation, and overall substation layout to minimize the degree and direction of oil spread. 5 The numbers in brackets correspond to those of the bibliography in Annex F. 10 Authorized licensed use limited to: Queen's University. Downloaded on August 25,2014 at 10:41:09 UTC from IEEE Xplore. Restrictions apply. Copyright © 2012 IEEE. All rights reserved.  IEEE Std 979-2012 IEEE Guide for Substation Fire Protection 5.4 Prevailing winds The prevailing wind direction should be taken into consideration when determining mineral-oil-insulated equipment locations. The prevailing winds can create an increase in the hazard from fires involving mineral- oil-insulated equipment and combustible structures. In a fire situation, the wind can cause the flame and fire plume to tilt. This can result in higher heat fluxes, smoke concentrations, and soot levels at downwind buildings or equipment. Additional fire protection measures may be considered when the wind is found to increase the fire hazard. Refer to A.5 for additional information. 5.5 Fire emergency response capability The fire response time and resources of either internal fire brigades or local fire departments are important factors in determining the required level of fire protection. The substation designer should consider these factors in the selection of fire protection mitigating measures in the substation design. Refer to A.6 for additional information. 5.6 Available firefighting water supplies In the event of a fire in the substation buildings or mineral-oil-insulated equipment, water is the most commonly used fire-extinguishing agent. As part of the design process, the available firefighting water supplies should be reviewed. Available water supply is an important design attribute for both automatic suppression systems that may be considered as well as for responding fire departments or fire brigades. Refer to A.7 for additional information. 5.7 Emergency access to the substation Access roads should be designed to accommodate emergency response vehicles. Provisions for emergency access at two locations should be considered around the station yard. Where feasible, vehicle entry gates should conform to the following: ⎯ Not be located beneath overhead power lines ⎯ Not be adjacent to fire hazards (such as mineral-oil-insulated transformers) that could cause them to be blocked during an incident ⎯ Be located as far apart as practical (a minimum of one half the overall station diagonal is recommended) Refer to A.8 for additional information. 11 Authorized licensed use limited to: Queen's University. Downloaded on August 25,2014 at 10:41:09 UTC from IEEE Xplore. Restrictions apply. Copyright © 2012 IEEE. All rights reserved.  IEEE Std 979-2012 IEEE Guide for Substation Fire Protection 6. Fire protection for substation buildings 6.1 General Substation buildings should be designed in accordance with applicable local building codes. In the absence of applicable building code requirements, the following recommendations may be followed for the design and construction of substation buildings. Fire protection may be applied to substation buildings that meet one or more of the following criteria or where fire protection is required by local codes: ⎯ The building area is greater than 1000 m2 (10 000 ft2). ⎯ The building is multistory. ⎯ The building contains mineral-oil-insulated equipment. As a minimum, all new substation buildings should be of noncombustible construction and should include the life safety recommendations in 6.9. 6.2 Use and occupancy In the absence of explicit local building code classification criteria, electrical equipment buildings and battery buildings should be classified as special-purpose industrial occupancies. Warehouse buildings should be classified as storage occupancies. Maintenance shop areas should be considered as industrial occupancies. Office areas separate from control building spaces should be considered business occupancies. Refer to A.9 for additional information. 6.2.1 Control buildings and rooms Control buildings and rooms should be reserved for control equipment, metering equipment, SCADA equipment, telemetry and communications equipment, low-voltage (