Technical Brief MTU Installation Guidelines A product of Aclara Technologies LLC Confidential and Proprietary Copyright 2013. All Rights Reserved. (Y20355-TEB Rev C) 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 This information may not be published, reporduced, or otherwise disseminated without the express written authorization of Aclara.
Table of Contents Warnings, Cautions, and Notes FCC/IC Compliance. . . . . . . . . . . . . . . . . . . . . . . . . . . . iii FCC/IC RF Exposure Guide . . . . . . . . . . . . . . . . . . . . . . . . iii Field Calibration Procedure . . . . . . . . . . . . . . . . . . . . . . . iii Overview Introduction . . . . . . . Support . . . . . . . . Deployment Process . . . Recommended Equipment Signal Propagation . . . . Free Space Attenuation . RF Absorption. . . . . . RF Reflection . . . . . . RF Shadowing . . . .
Table of Contents ii MTU Installation Guidelines
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 anual 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.
FCC/IC Compliance iv MTU Installation Guidelines
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 remote mount 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 recommended practices for installation.
Introduction Recommended Equipment Aclara recommends installers have the following equipment available during installation. A more detailed list for specific installations evironments is provided in Appendix A.
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.
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 an increase in the number of DCUs to improve communication.
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.
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. The image below illustrates how the downspout, iron pipe, and the AC unit all shadow the RF signal.
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.
Signal Propagation 8 MTU Installation Guidelines
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 In this example, the RF signal is reflected off of the iron fence and absorbed by the exterior wall of the home.
Mounting Considerations 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).
Exterior Mounting 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.
Mounting Considerations 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.
Interior Interior MTUs installed inside of a building should be mounted on an exterior wall that is not immediately facing a neighboring building. As with exterior installations, the MTU should 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. Check the signal prior to entering the building, and then again at the proposed mounting location.
Mounting Considerations 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.
Interior 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. • Mount the MTU so that the top is several inches below the ceiling.
Mounting Considerations Pit MTUs connected to meters located in meter pits may be mounted to approved, non-metallic pit lids. The MTUs should be mounted with the Aclara logo facing the pit lid, as shown in the following image. Pit lids that are ribbed on the underside require short spacers, while meter pit lids that are smooth on the underside require long spacers. Short spacers are marked with an S, and long spacers are marked with an L.
Pit MTU to pit lid mounting procedures vary according to pit lid model. Please refer to the appropriate pit lid installation instructions for specific mounting procedures. Summary • Mount the MTU to approved, non-metallic meter pit lids only. • Mount the MTU with the label facing the pit lid. • Use the appropriate spacers for the type of meter pit lid.
WIRING 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. The black inulated cable is for port 1, and the gray insulated cable is for port 2. Wire Length MTUs are provided with a standard wire length of 12 feet.
Connections Connections All connections must be made using silicone gel filled IDCs. Typical splice connectors will require removing approximately 1" of the outer cable jacket. CAUTION It is important that you do not damage the insulation of the inner conductors when removing the outer jacket. Aclara recommends you refer to the specific manufacturer for detailed installation instructions. The connectors must be installed according to the manufacturer’s instructions.
A PPENDIX CHAPTER 0 A RECOMMENDED EQUIPMENT CHAPTER0 This appendix provides a detailed list of recommended tools and supplies for specific installation types.
22 MTU Installation Guidelines
A PPENDIX CHAPTER 0 B CHECKLIST CHAPTER0 Use the following checklists to help verify the correct installation of MTUs.
