1、Transmission SystemsAPI RECOMMENDED PRACTICE 552 FIRST EDITION,OCTOBER 1994 REAFFIRMED,AUGUST 2015Transmission SystemsManufacturing,Distribution and Marketing DepartmentAPI RECOMMENDED PRACTICE 552FIRST EDITION,OCTOBER 1994REAFFIRMED,FEBRUARY 2007SPECIAL NOTES1.API PUBLICATIONS NECESSARILY ADDRESS P
2、ROBLEMS OF A GENERALNATURE.WITH RESPECT TO PARTICULAR CIRCUMSTANCES,LOCAL,STATE,AND FEDERAL LAWS AND REGULATIONS SHOULD BE REVIEWED.2.API IS NOT UNDERTAKING TO MEET THE DUTIES OF EMPLOYERS,MANU-FACTURERS,OR SUPPLIERS TO WARN AND PROPERLY TRAIN AND EQUIPTHEIR EMPLOYEES AND OTHERS EXPOSED CONCERNING H
3、EALTH ANDSAFETY RISKS AND PRECAUTIONS,NOR UNDERTAKING THEIR OBLIGATIONSUNDER LOCAL,STATE,OR FEDERAL LAWS.3.INFORMATION CONCERNING SAFETY AND HEALTH RISKS AND PROPERPRECAUTIONS WITH RESPECT TO PARTICULAR MATERIALS AND CONDI-TIONS SHOULD BE OBTAINED FROM THE EMPLOYER,THE MANUFACTURER,OR SUPPLIER OF TH
4、AT MATERIAL,OR THE MATERIAL SAFETY DATA SHEET.4.NOTHING CONTAINED IN ANY API PUBLICATION IS TO BE CONSTRUED ASGRANTING ANY RIGHT,BY IMPLICATION OR OTHERWISE,FOR THE MANU-FACTURE,SALE,OR USE OF ANY METHOD,APPARATUS,OR PRODUCTCOVERED BY LETTERS PATENT.NEITHER SHOULD ANYTHING CONTAINEDIN THE PUBLICATIO
5、N BE CONSTRUED AS INSURING ANYONE AGAINSTLIABILITY FOR INFRINGEMENT OF LETTERS PATENT.5.GENERALLY,API STANDARDS ARE REVIEWED AND REVISED,REAF-FIRMED,OR WITHDRAWN AT LEAST EVERY FIVE YEARS.SOMETIMES AONE-TIME EXTENSION OF UP TO TWO YEARS WILL BE ADDED TO THISREVIEW CYCLE.THIS PUBLICATION WILL NO LONG
6、ER BE IN EFFECT FIVEYEARS AFTER ITS PUBLICATION DATE AS AN OPERATIVE API STANDARD OR,WHERE AN EXTENSION HAS BEEN GRANTED,UPON REPUBLICATION.STATUS OF THE PUBLICATION CAN BE ASCERTAINED FROM THE APIAUTHORING DEPARTMENT TELEPHONE(202)682-8000.A CATALOG OF APIPUBLICATIONS AND MATERIALS IS PUBLISHED ANN
7、UALLY AND UPDATEDQUARTERLY BY API,1220 L STREET,N.W.,WASHINGTON,D.C.20005.Copyright 1994 American Petroleum InstituteiiiFOREWORDThis publication reflects the current practices in the transmission of instrument measure-ment and control signals in a refinery.Throughout this publication,soft-conversion
8、(calculated)units are provided in paren-theses following actual units.Soft-conversion units are provided for the users referenceonly.API publications may be used by anyone desiring to do so.Every effort has been madeby the Institute to assure the accuracy and reliability of the data contained in the
9、m;however,the Institute makes no representation,warranty,or guarantee in connection with this publi-cation and hereby expressly disclaims any liability or responsibility for loss or damageresulting from its use or for the violation of any federal,state,or municipal regulation withwhich this publicat
10、ion may conflict.Suggested revisions are invited and should be submitted to the director of the Manufac-turing,Distribution,and Marketing Department,American Petroleum Institute,1220 LStreet,N.W.,Washington,D.C.20005.vCONTENTSPage1Scope.12References.13General.13.1Advantages of Transmitted Signals.13
11、.2Design Considerations for Transmission Systems.13.3Electronic.13.4Pneumatic.13.5Fiber Optics.23.6Digital Field Bus.24General Information on Electronic Systems.24.1General.24.2Standard Electronic Signal Ranges.34.3Regulatory Codes and Recommended Practices.35Reducing Electrical Interference in Elec
12、tronic Systems.35.1Sources of Electrical Interference.35.2Minimizing Unwanted Voltages in Signal Transmission Circuits.45.3Instruments to be Interconnected.56Engineering Factors in Selection of Wire Types for Electronic Systems.66.1Process Controls with Milliampere Signals.66.2Process Controls with
13、Voltage Signals.66.3Digital Communications Signals.76.4Process Control Low Energy/Voltage Sensors.76.5Process Control with Pulse Output Meters.76.6Low-Impedance Sensors to Computers.76.7Turbine Meters.76.8Magnetic-Flow Transmitters.77Specifications for Wires and Cables in Electronic Systems.77.1Wire
14、 Size.77.2Stranded Wire.77.3Insulation.87.4Temperature Rating.87.5Overall Jacket.87.6Shielding.87.7Number of Crossovers.87.8Wire and Pair Identification.87.9Communication Wires.87.10Lightning Protection.88Typical Applications of Wire Types Used in Electronic Systems.89Guidelines for Separation of Wi
15、res in Electronic Systems.89.1Similar Signal Levels.89.2Signal and Power Wiring.89.3Proximity to AC Fields.910 Effect of Transmission Distance on Electronic Signal Installations.911 High Temperature Areas.912 General Information on Installation Methods for Electronic Systems.913 Installation of Tray
16、s for Electronic Systems.913.1Locations and Advantages.913.2Description.914 Installation of Raceways in Electronic Systems.1114.1General.11viPage14.2Aboveground Installations.1114.3Underground Installations.1114.4Routing.1215 Messenger Cable.1216 Surge Protection for Cables in Electronic Systems.1216.1General.1216.2Types of Electrical Surges.1316.3Types of Protective Devices.1316.4Selection and Installation of Surge Protection Devices.1617 Wiring for Field Mounted Process Instruments.1917.1Leaka