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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information may not be published, reporduced, or otherwise disseminated without the express written authorization of Aclara. Any
software or firmware described in this document is furnished under a license and may be used or copied only in accordance with the
terms of such license.
DISCLAIMER
The information in this document is subject to change without notice and should not be construed as a commitment by Aclara. Aclara
assumes no responsibility for any errors that may appear in this document.
No responsibility is assumed for the use or reliability of software on equipment that is not supplied by Aclara.
TWACS, STAR, and Metrum Cellular are registered trademarks of Aclara Technologies LLC.
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Table of Contents
Summary of Contents for Aclara MTU
- Page 1 DISCLAIMER The information in this document is subject to change without notice and should not be construed as a commitment by Aclara. Aclara assumes no responsibility for any errors that may appear in this document. No responsibility is assumed for the use or reliability of software on equipment that is not supplied by Aclara.
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Page 3: Table Of Contents
Table of Contents Warnings, Cautions, and Notes FCC/IC Compliance......iii FCC/IC RF Exposure Guide ......iii Field Calibration Procedure . - Page 4 Table of Contents M T U I n s t a l l a t i o n G u i d e l i n e s...
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Page 5: Warnings, Cautions, And Notes
FCC/IC RF Exposure Guide Aclara Technologies LLC low power RF devices and their antennas must be fixed-mounted on indoor or outdoor permanent structure(s) providing a separation distance of at least 20 cm from all persons during normal operation. This device is not designed (and it has no external connection) to operate in conjunction with any other antennas or transmitters. - Page 6 FCC/IC Compliance M T U I n s t a l l a t i o n G u i d e l i n e s...
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Page 7: Overview
If, at any time, you would like to speak with a Aclara representative about any product or service or if you do not have a user name and password to access the Portal, please... -
Page 8: Recommended Equipment
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. • Cable ties • Silicone gel filled electrical insulating IDCs (Aclara #043-1913) • Staple gun •... -
Page 9: Signal Propagation
Every Meter Transmission Unit (MTU) installation location presents its own set of variables, and this document is intended to help guide installers by providing general information about UHF radio transmissions and MTUs. -
Page 10: Free Space Attenuation
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. -
Page 11: Rf Reflection
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. -
Page 12: Rf Shadowing
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. M T U I n s t a l l a t i o n G u i d e l i n e s... - Page 13 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.
- Page 14 Signal Propagation M T U I n s t a l l a t i o n G u i d e l i n e s...
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Page 15: Mounting Considerations
Exterior Mounting Issues with performance of exterior mounted MTUs are typically the result of mounting the MTU too low, or mounting it in such a way that it is blocked by various obstructions. In the following real world example, the MTU is mounted between the protruding exterior wall and the hose reel, both of which absorb the RF signal. - Page 16 Exterior Mounting In this example, the RF signal is reflected off of the iron fence and absorbed by the exterior wall of the home. M T U I n s t a l l a t i o n G u i d e l i n e s...
- Page 17 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).
- Page 18 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.
- Page 19 • 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. • When mounting multiple MTUs in the same location, leave at least 4 inches between the MTUs if mounting side by side, and at least 3 inches between MTUs if mounting one above another.
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Page 20: Interior
In this case, the RF signal is not only directed towards the floor, but heavily shadowed by the pipes. The MTU should be mounted to the wall and away from the metal pipes, as shown below. M T U I n s t a l l a t i o n G u i d e l i n e s... - Page 21 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.
- Page 22 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.
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Page 23: Pit
Mounting Considerations 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. - Page 24 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.
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Page 25: Wiring
MTUs are provided with a standard wire length of 12 feet. If necessary, additional wire may be used to extend the range between the meter and the MTU up to 500 feet. (Some meters require shorter wire lengths. Please refer to the meter manufacturer’s documentation for exact limitations.) Always use cable of with 22... -
Page 26: Connections
It is important that you do not damage the insulation of the inner conductors AUTION 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. - Page 27 3 Conductor, 22 AWG, solid copper wire w/black jacket 3 Conductor, 22 AWG, solid copper wire w/gray jacket Gel-filled, insulation displacement connectors (Aclara #043-1913, or equivalent) Direct burial splice kits (Aclara #043-1912, or equivalent) Short MTU spacers (Aclara #056-8150S) Long MTU spacers (Aclara #056-8150L)
- Page 28 M T U I n s t a l l a t i o n G u i d e l i n e s...
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Page 29: Appendix B: Checklist
Is there minimum of 6 inches of clearance between the MTU and any pipes, conduit, downspouts, etc.? Is there a minimum of 5 feet of clearance between the MTU and any large metal objects, such as dumpsters, HVAC ducts, or cabinets? Is there any damage to the wiring (e.g.
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