This file is raw output from pdftotext and may not be ideal for distribution. If you are a maintainer for Hackipedia, please sit down when you have time and clean this text version up. Source PDF: /mnt/main/jmc-storage/docs/SCTE/ANSI SCTE 044 Test Method for DC Loop Resistance (2010).pdf Like all conversions the text below should be fully readable as UTF-8 unicode text. --------------------------------------------------------------- ENGINEERING COMMITTEE Interface Practices Subcommittee AMERICAN NATIONAL STANDARD ANSI/SCTE 44 2010 Test Method for DC Loop Resistance NOTICE The Society of Cable Telecommunications Engineers (SCTE) Standards are intended to serve the public interest by providing specifications, test methods and procedures that promote uniformity of product, interchangeability and ultimately the long term reliability of broadband communications facilities. These documents shall not in any way preclude any member or nonmember of SCTE from manufacturing or selling products not conforming to such documents, nor shall the existence of such standards preclude their voluntary use by those other than SCTE members, whether used domestically or internationally. SCTE assumes no obligations or liability whatsoever to any party who may adopt the Standards. Such adopting party assumes all risks associated with adoption of these Standards or Recommended Practices, and accepts full responsibility for any damage and/or claims arising from the adoption of such Standards or Recommended Practices. Attention is called to the possibility that implementation of this standard may require use of subject matter covered by patent rights. By publication of this standard, no position is taken with respect to the existence or validity of any patent rights in connection therewith. SCTE shall not be responsible for identifying patents for which a license may be required or for conducting inquires into the legal validity or scope of those patents that are brought to its attention. Patent holders who believe that they hold patents which are essential to the implementation of this standard have been requested to provide information about those patents and any related licensing terms and conditions. Any such declarations made before or after publication of this document are available on the SCTE web site at http://www.scte.org. All Rights Reserved © 2005, 2010 Society of Cable Telecommunications Engineers, Inc. 140 Philips Road Exton, PA 19341 i TABLE OF CONTENTS 1.0 SCOPE .........................................................................................................2 2.0 EQUIPMENT...............................................................................................2 3.0 PROCEDURE ..............................................................................................2 4.0 CALCULATIONS .......................................................................................3 5.0 REPORT ......................................................................................................4 6.0 ACCURACY ...............................................................................................4 1 1.0 SCOPE 1.1 This method is intended for use in determining the DC Loop Resistance of coaxial cables. Due to low resistances a four-wire test method is used. 2.0 EQUIPMENT 2.1 Fluke PM 6304 Programmable Automatic RCL Meter, or equivalent. 2.2 Four wire test leads as required. 3.0 PROCEDURE 3.1 Strip approximately 1 inch (2.54 cm) of the insulation exposing the inner conductor on both ends of the cable under test. Also, expose enough outer conductor or braid to make a good connection with the test leads. Cables tested on a reel must be constructed with outer jacket insulation. 3.2 Calibrate the RCL meter by connecting the leads together and performing the appropriate trim or calibration as required by the manufacturer. 3.3 Connect the measurement leads, see Figure 1, one lead to the center conductor on one end of the cable, and the other lead directly to the same conductor on the opposite end. Measure DC resistance. Record this value as Rcc. 3.4 Following the same procedure connect one test lead to the outer conductor of the cable, and the other directly to the same conductor on the opposite end. Measure DC resistance. Record this value as Roc. 3.5 After both conductors of the cable have been measured, determine temperature of test in degrees F. Note: Cable should stabilize in its environment for 24 hours. 2 + Source Sense - Figure 1: 4 Wire DC Resistance Measurement Note: Ensure a good connection of the leads to the conductor(s) under test. 4.0 CALCULATIONS 4.1 The conductor resistance varies with length and temperature. The conversion from per reel or length to specified values are as follows: RLoop = (Rcc + Roc) Where: Rcc = Center Conductor Resistance Roc = Outer Conductor Resistance Resistance, Ohms per 1000 feet = (RLoop * 1000)/L (feet) Resistance, Ohms per 1000 meter = (RLoop * 1000)/L (meters) Where: RLoop = Measured Loop Resistance (Ohms) 3 L = Length of Reel (Feet) or (Meters) 4.2 Resistance requirements are usually given as 68 F (20 C). Values obtained at temperatures other than 68 F can be corrected to 68 F as follows: R Resistance at 68 F, Ohms = 1 .0022(T 68) Where: R = The resistance of the specimen at the test temperature (Ohms) T = The temperature of the test ( F) 0.0022 = ( F) Temperature coefficient of resistivity. Note: Temperature coefficient of resistivity is valid for both copper and aluminum. 5.0 REPORT 5.1 Date 5.2 Specimen identification (Type, Reel No., etc.) 5.3 Inner conductor resistance, outer conductor resistance, loop resistance per reel length and per specification requirement (uncorrected and corrected to 68 F) 5.4 Specimen Length 5.5 Temperature of Test 6.0 ACCURACY 6.1 The accuracy of this measurement depends on several factors. Since the DC resistance values are specified in Ohms/(1000 feet) or (km), one should measure a length 1000 feet for drop cable and a length 2000 feet for Trunk & Distribution type cable. Also, the accuracy of the recorded specimen length, the recorded temperature, and lead connections are important. Overall accuracy, 4 however, can be assumed within the published accuracy figures for the meter itself considering the resistance value being measured. 5