1、NEMA Standards PublicationNational Electrical Manufacturers AssociationNEMA SBP 3-2017The Changing Communications Within Fire Alarm System ReportingA NEMA Fire, Life Safety, Security, and Emergency Communication Section White Paper SBP 3-2017 The Changing Communications Within Fire Alarm System Repo
2、rting Prepared by National Electrical Manufacturers Association 1300 North 17th Street, Suite 900 Rosslyn, Virginia 22209 www.nema.org 2017 National Electrical Manufacturers Association. All rights, including translation into other languages, reserved under the Universal Copyright Convention, the Be
3、rne Convention for the Protection of Literary and Artistic Works, and the International and Pan American copyright conventions. NEMA SBP 3-2017 Page 1 2017 National Electrical Manufacturers Association The Changing Communications Within Fire Alarm System Reporting Executive Summary The North America
4、n communications infrastructure is quickly changing. Over the last ten years, technology has changed more than the previous one hundred. Technologys rate of development is expected to continue escalating such that the next ten years will bring more change than the past ten. This technological explos
5、ion directly impacts the fire alarm industry in many ways including: fire detection, notification, panel operations, and alarm signal transmission via a rapidly evolving global communications infrastructure. The requirements of NFPA 72 for fire alarm system communications between a protected premise
6、s fire alarm system and the supervising station have kept up with technology in some ways and have been left behind in other ways. This publication discusses todays options for fire alarm system communications. Development Prior to 1993, fire alarm communications and offsite monitoring of fire alarm
7、 systems requirements were found in NFPA 71, Standard for Central Station Service. With all NFPA signaling standards combined into one document, these requirements were relocated to Chapter 4 of NFPA 72-1993, National Fire Alarm Code. The organization of the National Fire Alarm Code has changed from
8、 time to time since then, but the requirements can still be found in the Supervising Stations Chapter (currently, Chapter 26 of NFPA 72-2016, National Fire Alarm and Signaling Code). In the past, when a developer of a communications technology wanted to bring a product to market, the following proce
9、dure was required: a) The new technology would be brought to the NFPA Technical Committee, where it would have been discussed during the code development cycle. b) If the NFPA Technical Committee found the technology viable, the technology along with all of its technical information was added to the
10、 standard. c) Once the NFPA standard was published, the manufacturer could get the product listed and take it to market. The NFPA Technical Committee rated all proposed technologies using informal guidelines composed of of three major components: a) The probability of getting a signal through called
11、 “throughput probability;” b) Procedure for notification of sender and receiver when the communications process was interrupted;and c) Robustness of the technology against normal causes of outages. In the 1980s when technology was evolving at a more leisurely pace, this process worked. Through the 1
12、990s and into the 21st century, the NFPA Technical Committee realized that this time-honored process was too slow. NEMA SBP 3-2017 Page 2 2017 National Electrical Manufacturers Association Legacy Technologies The lineup of possible legacy technologies in the National Fire Alarm Codethrough the 2007
13、edition included the following: a) Active Multiplex b) Digital Alarm Communications Systems c) McCulloh Systems d) Two Way Radio Frequency Multiplex Systems e) One Way Private Radio Alarm Systems f) Directly Connected Noncoded Systems g) Private Microwave Radio Systems This lineup provided specific
14、technical requirements for each of the technologies listed, which were virtually unchanged since they were initially included in the standard. Development of Other Technologies In 1999, a new section was added to the National Fire Alarm Code titled “Other Transmission Technologies” (Section 5-5.4, N
15、FPA 72-1999). The Supervising Stations Technical Committee developed this section in recognition that technological evolution was quickly outpacing standards development. The traditional process of adding a section to the standard each time a specific new technology was developed was inefficient, ca
16、used confusion, and significantly delayed acceptance of new technology. The new section on “Other Transmission Technologies” is based on a number of common performance based design requirements and features that any new transmission technology must meet to be eligible for listing. Chief among these
17、design features were signal throughput probability, interruption notification, and robustness of the technology. If a product based on new technology conforms to these performance requirements, it could be taken directly to a Nationally Recognized Test Laboratory for listing and then made available
18、in the market in timely manner. NFPA 72-2010 Housecleaning Efforts In 2010, the technical committee reexamined each of the transmission technologies in the standard using the “Other Transmission Technologies” section as a litmus test to determine whether the legacy methods in view of the current com
19、munication infrastructure, continue to be an acceptable alarm transmission technology. After this examination, the following legacy methods were eliminated from the 2010 edition of the standard: Active Multiplex Active multiplex is a logical evolution from McCulloh and direct wire. The idea was to u
20、tilize a single pair of wires to communicate with multiple protected premises. The idea was to assign unique identifiers to each property and the remote monitoring facility could sequentially interrogate and receive data from each subscriber. This was a radical departure from direct connect as there
21、 was no continuous connection and therefore continuous supervision between the remote station and subscriber. This resulted in establishment of minimum times to report an alarm and trouble at the remote monitoring facility and subsequently loading tables for the number of alarm systems on a communic
22、ations channel. A unique evolution of active multiplex systems known as “derived local channel” was developed by Wisconsin Bell in 1983 with the collaboration of several local fire alarm monitoring companies in Wisconsin. The system used a single telephone line, with an adapter that split the bandwi
23、dth between voice and fire alarm data. Similar to todays DSL units, this was a great leap forward for the era. With a single telephone line, one could have an “always on” connection to the fire alarm control panel and still NEMA SBP 3-2017 Page 3 2017 National Electrical Manufacturers Association us
24、e the telephone line for normal voice communications. Eventually, the specialized equipment required for this system became unavailable, and this method fell into disuse. Since all requirements of “Other Transmission Technologies” were met with this method, elimination of this method would cause no
25、damage to any derived local channel systems still in use. McCulloh McCulloh systems are an even older technology dating back to the late nineteenth century. These were wind-up wheels with cams that transmitted a signal (originally via telegraph) to a fire alarm dispatch center. After transmission, t
26、he McCulloh wheel would need to be manually rewound, which was the beginning of a requirement for a runner service for central station service. Todays requirement for a runner to be dispatched when equipment needs to be reset by the prime contractor Section 26.3.7.1.2 (2), NFPA 72-2010 continues thi
27、s historical need. Since direct copper connections were required and the signals did not travel far, subsidiary stations were required. As monitoring became regionalized and then became national in scope, this form of transmission lost favor. Since McCulloh meets the minimum requirements of the “Oth
28、er Transmission Technologies” section, McCulloh was eliminated in the 2010 edition of the National Fire Alarm and Signaling Code. Directly Connected Non-Coded Systems Directly connected non-coded systems were developed for use with remote station fire alarm systems. The remote station standard, NFPA
29、 72C, was first issued in 1960, when the fire service attempted to diversify from simply firefighting to other emergency services. They believed that monitoring fire alarm systems directly at the fire station or emergency dispatch center would be a good idea. Directly connected non-coded systems use
30、d sub-voice grade copper telephone lines, and incorporated a polarity-reversal technique to signal the fire service dispatch center. Unfortunately, this system only transmitted a fire alarm signal, and did not include supervisory or trouble signals originating at the fire alarm control panel. Since
31、it was a “general” fire alarm signal, annunciator panels were required to be installed at each protected premises to indicate specific zone or point of initiation. As local telephone companies began removing copper lines and no longer making the Series 1000 sub-voice lines available, this technology
32、 became outdated and was removed from the 2010 edition of NFPA 72. However, any existing directly connected non-coded systems still meet the requirements of “Other Transmission Technologies.” Private Microwave Radio Systems Private microwave radio systems were provided by a handful of manufacturers
33、in the early 1980s. Since no private microwave radio systems survived, and the testing labs reported that no private microwave radio systems are currently listed, this technology was removed from the 2010 edition of the National Fire Alarm and Signaling Code. NEMA SBP 3-2017 Page 4 2017 National Ele
34、ctrical Manufacturers Association NFPA 72-2010 Organization With the elimination of the four legacy methods discussed above, the organization of the transmission technologies section of NFPA 72-2010 was changed to require compliance with “Other Transmission Technologies” (changed in 2010 to “General
35、”), with exceptions for digital alarm communications systems (DACS) and Radio, which were found to be not in compliance with the performance requirements of “Other Transmission Technologies”. Separate sections of NFPA 72 are dedicated to DACS and to radio. If DACS is selected as a transmission techn
36、ology, the DACS section should be followed. If any listed radio technology is used, the radio sections (one-way and two-way) should be consulted for the performance requirements. Digital Alarm Communications Systems (DACS) DACS were first introduced to the technical committee in the mid-1980s and we
37、re rejected by the technical committee twice because it had been determined that using regulartelephone lines was not reliable enough. It is important to realize that this was the first time that any proposed communications method was not controlled end-to-end by the technical committee. Instead, it
38、 was proposed to be under NFPA jurisdiction only to the demark at the protected premises and through the AT it is in the industrys best interest to stay involved and continue to be ever vigilant Principal Author, Art Black Principal, Carmel Fire Protection Associates Task Group Committee Andrew Be
39、rezowski Dan Finnegan Thanks to the Society of Fire Protection Engineers for permission to use much of the content of a third quarter 2011 article from Fire Protection Engineering as the basis for this white paper. NATIONAL ELECTRICAL MANUFACTURERS ASSOCIATION 1300 NORTH 17TH STREET, SUITE 900 ROSSLYN. VA 22209www.NEMA.orgTO ORDER ADDITIONAL NEMA STANDARDS VISITWWW.GLOBAL.IHS.COM OR CALL 1-800-854-7179/1-303-397-79565612_0514TB
