DRAFT Technical Brief MTU Installation Requirements A product of Aclara Technologies LLC Confidential and Proprietary Copyright 2013-16. All Rights Reserved. (Y20355-TEB Rev E) PROPRIETARY NOTICE The information contained in this document is private to Aclara Technologies LLC an Ohio limited liability company (Aclara). This information may not be published, reporduced, or otherwise disseminated without the express written authorization of Aclara.
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DRAFT Table of Contents Warnings, Cautions, and Notes FCC/IC Compliance. . . . . . . . . . . . . . . . . . . . . . . . . . . . iii Overview Support . . . . . . . . Deployment Process . . Signal Propagation . . . Free Space Attenuation RF Absorption. . . . . RF Reflection . . . . . RF Shadowing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table of Contents ii DRAFT MTU Installation Requirements
DRAFT WARNINGS, CAUTIONS, AND NOTES Always consult and adhere to all local and national safety codes, regulations, and standards.WARNING, CAUTION and Note statements are used throughout this manual to emphasize important and critical information to help you ensure safety and prevent product damage.These statements are defined below. WARNING indicates a potentially hazardous situation which, if not avoided, could result in death or serious physical injury.
DRAFT Conformité FCC/IC AVERTISSEMENTS, MISES EN GARDE ET REMARQUES Toujours consulter et respecter les codes, règlements et normes de sécurité locaux et nationaux. Des AVERTISSEMENTS, MISES EN GARDE et remarques sont utilisés tout au long de ce guide pour souligner l'information importante et critique qui vous aidera à assurer la sécurité et à prévenir les dommages au produit. Ces énoncés sont définis ci-dessous.
DRAFT OVERVIEW Meter Transmission Units (MTUs) are the endpoints of the STAR system. MTUs are permanently sealed devices that transmit regularly scheduled meter readings on an FCC licensed frequency to a Data Collector Unit, or DCU. Every Meter Transmission Unit (MTU) installation location presents its own set of variables. This document is intended to help guide installers by providing general information about UHF radio transmissions, MTUs, and Aclara required practices for installation.
DRAFT Deployment Process Deployment Process MTU deployment can be broken down into three basic steps. These are: 1. Mounting the MTU 2. Routing and connecting the wiring 3. Programming and configuring the MTU The scope of this document is limited to the mounting and wiring portions of the deployment process.
DRAFT Overview Signal Propagation The STAR Network operates in the range of 450 - 470 Megahertz (MHz). Frequencies in this range are specifically licensed by the FCC for business use, and are considered to be part of the Ultra-High Frequency (UHF) band of radio communications. As with all UHF communications, there are certain factors that affect the propagation of the radio transmissions.
DRAFT Signal Propagation Free Space Attenuation Free space attenuation is the natural loss in signal strength that occurs when radio waves pass through open air. This loss in signal strength is proportionate to the distance between the transmitter and the receiver. While the actual installation of the MTU will not change the free space attenuation considerably, certain locations may require the use of an extended range MTU or additional DCUs to improve communication.
DRAFT Overview RF Reflection RF reflection occurs when objects made of conductive materials (typically metal) are in or near the transmission path. While reflection itself may not negatively affect system performance, the RF signal may be reflected into an absorbing material such as dense foliage or the concrete foundation of a building. Common objects that reflect RF signals are metal buildings such as sheds or warehouses, metal fences, HVAC ducts, vehicles, and metal signs.
DRAFT Signal Propagation RF Shadowing RF shadowing is a phenomenon related to absorption and reflection that occurs when a transmitter is too close to another object. Shadowing occurs when a nearby object absorbs or reflects a signal. The image below illustrates how the downspout, iron pipe, and the AC unit all shadow the RF signal.
DRAFT Overview The signal is narrowest when it first leaves the MTU. The closer an object is to the MTU, the greater the impact the object will have on the signal. This is illustrated in the image below, where the close proximity of the garbage dumpster is blocking the signal from the MTU. Simply moving the dumpster several feet away from the MTU allows a greater portion of the signal to propagate.
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DRAFT MOUNTING CONSIDERATIONS The following sections describe the nature of RF signal transmission in the UHF frequency range, and specific factors to consider when installing an MTU on the exterior of a building, inside a building, or in a meter pit. Regardless of the installation environment, the MTU must be mounted securely.
Exterior Mounting DRAFT In this example, the RF signal is reflected off of the iron fence and absorbed by the exterior wall of the home. Simply raising the MTU above the fence and moving it to the end of the home (B) will drastically reduce the amount of RF energy reflected by the fence and improve system communication. The ideal location for the MTU, however, is on the front of the home (A).
DRAFT Mounting Considerations The image below illustrates how the hose reel, the meter, and the wall ledge all shadow the RF signal. Raising the MTU above the ledge and moving it to the edge of the building eliminates the shadowing effect of the meter, ledge, and hose reel.
DRAFT Exterior Mounting Summary • Mount the MTU as high as possible. The MTU must be mounted at or above grade (ground level). • Mount the MTU with the Aclara logo facing the installer. • Mount the MTU at least six inches away from any metal objects, including pipes, conduit, and downspouts. • Mount the MTU so that the top is at least one inch below the siding overlap.
DRAFT Mounting Considerations Interior MTUs installed inside of a building must be mounted near (but not on) an exterior wall that is not immediately facing a neighboring building. As with exterior installations, the MTU must be mounted perpendicular to the ground with the Aclara logo facing the installer. TIP Use a cellular phone’s signal strength indicator to gauge the amount of signal interference within a building.
Interior DRAFT Mount the MTU at least 5-10 feet away from large metal objects like furnaces, duct work, refrigerators, and cabinets. In the example below, the MTU is mounted between the HVAC duct and the refrigerator. Both of these large metal objects will interfere with the RF signal.
DRAFT Mounting Considerations Moving the MTU several feet away from the duct and the refrigerator will eliminate the interference and increase system performance considerably. Summary • Mount the MTU as high as possible near an exterior wall. The MTU must be mounted at or above grade (ground level). • Mount the MTU perpendicular to the ground with the Aclara logo facing the installer. • Mount the MTU at least six inches away from pipes and conduit.
DRAFT Pipe Mounting Pipe Mounting Aclara offers a Pipe Mount Kit (P/N #109-3221-A) that allows remote mount MTUs to be attached to either horizontal or vertical pipes with outside diameters of 2 - 4 inches. This kit includes an MTU bracket, screws, and stainless steel, self-locking cable ties. Please refer to the MTU Pipe Mount Kit Installation Instructions (Y20369-TUM) included with the kit for more detailed information.
DRAFT Mounting Considerations Pit When mounting inside a meter pit, MTUs should either be connected to an optional Meter Pit Antenna (please see the Meter Pit Antenna Installation Instructions Y63129-TUM for more information), or mounted to an Aclara approved, non-metallic pit lid. When mounting to a non-metallic pit lid, the MTUs must be mounted with the Aclara logo facing the pit lid. Screws and cable ties used in pit installations must be 18/8 (SAE Type 304) stainless steel.
DRAFT Pit Spacers When mounting a 501-8150 or Series 3000 MTU to the pit lid without a MTU mounting relief, the use of a spacer is sometimes required. There are two options for spacers, a short spacer and a long spacer. Short spacers (P/N 056-8150S) are marked with an S, and long spacers (P/N 056-8150L) are marked with an L. Short Spacers The short spacers are used to bring the mounting surface flush with the face of the MTU and prevent damage to the MTU enclosure.
DRAFT Mounting Considerations Use the short spacer if the lid is flat, and does not have MTU mounting provisions, OR has mounting provisions that are even with the bottom of the lid. Long Spacers In some rare situations the use of the tall spacer is needed. The tall spacers are used when the bottom of the pit lid is not flat and there are no provisions for mounting the MTU. The need for the Long spacer is specified at the time of lid qualification.
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DRAFT WIRING MTUs are provided with a standard cable length of 12 feet. MTU cables are 22 AWG, solid copper wires with UV resistant insulation jacket. All wiring must be consistent with the wiring provided with the MTU and adhere to local and national codes. Cable Insulation Most MTUs are shipped with black cable insulation. Dual port MTUs, however will have two cables: one with black insulation and one with gray insulation.
DRAFT Connections Connections Please refer to the specific connector manufacturer for detailed installation instructions. The connectors must be installed according to the manufacturer’s instructions. CAUTION It is important that you do not damage the insulation of the inner conductors when removing the outer jacket. Please consult the appropriate meter installation instructions for specific MTU wiring instructions.
DRAFT Wiring Meter Pit Environment All wire connections that are in a pit environment must be made using direct bury splice kits (Aclara P/N 043-1912). These kits are C-UL-US Listed for use in wet, damp, direct bury, and submersible locations. Refer to the manufacturer’s installation instructions for more information.
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DRAFT A PPENDIX CHAPTER 0 A EQUIPMENT CHAPTER0 This appendix provides a detailed list of tools and supplies for specific installation types.
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DRAFT A PPENDIX CHAPTER 0 B CHECKLIST CHAPTER0 Use the following checklists to help verify the correct installation of MTUs.
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