ATIS - Alliance for Telecommunications Industry Solutions
Scope
This document harmonizes voltage@ current@ power@ and safety standards/precautions for near-end line-powering equipment operating at less than or equal to 200 Vdc to ground and far-end line-powered telecommunications equipment. It also addresses the calculation of voltage drop and power loss on the intervening pairs@ interoperability between near-end and far-end line-power equipment from differing vendors@ electrical protection and service continuity during low-level transient events caused by ac induction@ and Ground Potential Rise (GPR). Line-powering voltages covered by this standard are Class A1@ A2@ and A3 as defined in GR-1089-CORE [21]. Background Purpose Line-powering (including express/span powering) is the use of the twisted pair copper plant (19-26 AWG) to pass dc power from a source in a building or cabinet to an outside plant remote cabinet/enclosure@ or equipment located on or within another building. Telecommunications networks have a long history of using line-powering for various tasks@ such as the coin return mechanism of payphones@ T-1 repeater powering@ High-bit-rate Digital Subscriber Line (HDSL) remote unit powering@ Fiber-To-The-Curb (FTTC) powering@ Digital Data Service (DDS)@ etc. Line-powering remains popular for existing and emerging technologies because it does not require placement of power company meters@ rectifiers@ and batteries at remote locations. Even though power is dissipated (I2R losses) in the transmission of line power@ it is still often more cost effective for the relatively small wattage needs compared to placing ac power and associated power-conditioning equipment at the remote end. Line-powering voltages commonly found in the industry and addressed by Telcordia NEBS document GR-1089- CORE [21]@ ITU-T recommendation K.50 [15]@ and UL/CSA Standards 60950-1 [23]@ 60950-21 [25]@ 62368-1 [11]@ and 62368-3 [12] are less than 200 V with respect to ground (e.g.@ nominal -48 Vdc@ -130@ -190@ ??130@ ??145@ ??190@ etc.). Line-powering voltages are either positively ground-referenced@ or bipolar center-tap ground-referenced (e.g.@ ??130@ ??145@ ??190 Vdc). Negative voltage on the energized conductor(s)@ such as a nominal -130 V system@ limits corrosion (versus a negative ground-referenced system) of the copper pairs when water intrusion occurs in OSP cables. In addition to the information on line-powering in the above-referenced documents@ there are maximum power and current limits in the NEC? (National Electrical Code? and NEC? are registered trademarks of the National Fire Protection Association@ Quincy@ MA) [4]@ Canadian Electrical Code [8]@ and National Electrical Safety Code (NESC) [3]; maximum voltage@ power@ and current limits in ANSI/ATIS-0600337 [2]; and additional electrical protection information for line-powering schemes in ANSI/ATIS-0600332 [1]. These various standards define telecommunications line-powering voltage limits@ power limits@ and safety-related precautions. This document is an attempt to bring the requirements@ standards@ and precautions from all of these documents (and relevant information from a few other sources) into a single consistent source@ as well as provide user guidance on the engineering and application of line-powered equipment and cable. This standard is intended to define line-powering circuit characteristics (e.g.@ voltage windows@ power maximums) going forward@ rather than cover all of the legacy systems. This does not preclude the use of other voltages and systems@ but allows for interoperability of systems designed to this document. This standard also addresses performance of line-powering systems in fault conditions and provides manufacturers@ installers@ and users of line power systems with a consistent fault condition testing and recording method. The fault current levels determined through this analysis can be compared to standards IEC 60479-1 [9]@ Effects of Current on Human Beings and Livestock@ Part 1- General Aspects and IEC 60479-2 [10]@ Effects of Current on Human Beings and Livestock@