1、 AMERICAN NATIONAL STANDARD ANSI/ISA-50.00.01-1975 (R2012) Compatibility of Analog Signals for Electronic Industrial Process Instruments Approved 17 July 2012 ANSI/ISA-50.00.01-1975 (R2012) Compatibility of Analog Signals for Electronic Industrial Process Instruments ISBN: 978-1-937560-54-6 Copyrigh
2、t 2012 by the International Society of Automation (ISA). All rights reserved. Not for resale. Printed in the United States of America. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means (electronic mechanical, photocopying, recordi
3、ng, or otherwise), without the prior written permission of the Publisher. ISA 67 Alexander Drive P.O. Box 12277 Research Triangle Park, North Carolina 27709 - 3 - ANSI/ISA-50.00.01-1975 (R2012) Preface This preface, as well as all footnotes and annexes, is included for information purposes and is no
4、t part of ANSI/ISA-50.00.01-1975 (R2012). This document has been prepared as part of the service of ISA toward a goal of uniformity in the field of instrumentation. To be of real value, this document should not be static but should be subject to periodic review. Toward this end, the Society welcomes
5、 all comments and criticisms and asks that they be addressed to the Secretary, Standards and Practices Board; ISA; 67 Alexander Drive; P. O. Box 12277; Research Triangle Park, NC 27709; Telephone (919) 549-8411; Fax (919) 549-8288; E-mail: standardsisa.org. The ISA Standards and Practices Department
6、 is aware of the growing need for attention to the metric system of units in general, and the International System of Units (SI) in particular, in the preparation of instrumentation standards. The Department is further aware of the benefits to USA users of ISA standards of incorporating suitable ref
7、erences to the SI (and the metric system) in their business and professional dealings with other countries. Toward this end, this Department will endeavour to introduce SI-acceptable metric units in all new and revised standards, recommended practices, and technical reports to the greatest extent po
8、ssible. IEEE/ASTM SI 10, American National Standard for Metric Practice, and future revisions, will be the reference guide for definitions, symbols, abbreviations, and conversion factors. It is the policy of ISA to encourage and welcome the participation of all concerned individuals and interests in
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10、hat ISA develops. CAUTION ISA DOES NOT TAKE ANY POSITION WITH RESPECT TO THE EXISTENCE OR VALIDITY OF ANY PATENT RIGHTS ASSERTED IN CONNECTION WITH THIS DOCUMENT, AND ISA DISCLAIMS LIABILITY FOR THE INFRINGEMENT OF ANY PATENT RESULTING FROM THE USE OF THIS DOCUMENT. USERS ARE ADVISED THAT DETERMINAT
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14、NG WHETHER ANY LICENSING TERMS OR CONDITIONS PROVIDED IN CONNECTION WITH SUBMISSION OF A LETTER OF ASSURANCE, IF ANY, OR IN ANY LICENSING AGREEMENTS ARE REASONABLE OR NON-DISCRIMINATORY. ANSI/ISA-50.00.01-1975 (R2012) - 4 - ISA REQUESTS THAT ANYONE REVIEWING THIS DOCUMENT WHO IS AWARE OF ANY PATENTS
15、 THAT MAY IMPACT IMPLEMENTATION OF THE DOCUMENT NOTIFY THE ISA STANDARDS AND PRACTICES DEPARTMENT OF THE PATENT AND ITS OWNER. ADDITIONALLY, THE USE OF THIS DOCUMENT MAY INVOLVE HAZARDOUS MATERIALS, OPERATIONS OR EQUIPMENT. THE DOCUMENT CANNOT ANTICIPATE ALL POSSIBLE APPLICATIONS OR ADDRESS ALL POSS
16、IBLE SAFETY ISSUES ASSOCIATED WITH USE IN HAZARDOUS CONDITIONS. THE USER OF THIS DOCUMENT MUST EXERCISE SOUND PROFESSIONAL JUDGMENT CONCERNING ITS USE AND APPLICABILITY UNDER THE USERS PARTICULAR CIRCUMSTANCES. THE USER MUST ALSO CONSIDER THE APPLICABILITY OF ANY GOVERNMENTAL REGULATORY LIMITATIONS
17、AND ESTABLISHED SAFETY AND HEALTH PRACTICES BEFORE IMPLEMENTING THIS DOCUMENT. THE USER OF THIS DOCUMENT SHOULD BE AWARE THAT THIS DOCUMENT MAY BE IMPACTED BY ELECTRONIC SECURITY ISSUES. THE COMMITTEE HAS NOT YET ADDRESSED THE POTENTIAL ISSUES IN THIS VERSION. The following individuals served as mem
18、bers of the 1975 ISA50 committee: NAME COMPANY V. Tivy, Chairman Bailey Meter Company M. Bergston Barber-Coleman Company D. Boyd Universal Oil Products Company C. Buehler Taylor Instrument Division, Sybron Corporation R. Dallimonti Honeywell Inc. E. Davis Consultant R. Deuschle Fisher Controls Corpo
19、ration M. Bradner The Foxboro Company R. Horne Beckman Instruments, Inc. E. Ida E.I du Pont de Nemours also see Annex A.) 4.5.1 “Fully Isolated“ shall mean that the power, output and electrical signal input terminals (where provided) are all electrically isolated from each other. - 13 - ANSI/ISA-50.
20、00.01-1975 (R2012) Figure 1 Consideration of transmitter types ANSI/ISA-50.00.01-1975 (R2012) - 14 - Figure 2 Consideration of electrical isolation for transmitters - 15 - ANSI/ISA-50.00.01-1975 (R2012) 4.5.2 “Input Isolated“ shall mean that the signal input terminals are electrically isolated from
21、all other terminals. 4.5.3 “Output Isolated“ shall mean that the output terminals are electrically isolated from all other terminals. 4.5.4 “Power Isolated“ shall mean that the power terminals are electrically isolated from all other terminals. 4.5.5 “Electrically Isolated“ in the above definition i
22、s used per the meaning in 2.11. 4.5.6 “Non-Isolated“ shall mean that electrical connections exist internally or externally between all terminals. 4.5.7 “Grounded Output“ shall mean that one side of the output signal will normally become grounded through the instrument mounting unless it is intention
23、ally isolated from earth ground. 4.6 Ripple and noise content The peak to peak ripple and total noise level shall not exceed 0.25% of the maximum signal. This is further defined as not exceeding 10 mV peak to peak on a 5 volt signal (derived by resistive drop from a 20 mA signal, or a voltage signal
24、) when measured at the output of a 10 Hz low pass, single stage R-C filter and when operated from a dc test power source having the maximum allowed ripple and noise permitted in 6.5.2, or from its normal ac power supply. (See Annex A.) 5 Standard receivers 5.1 Inputs 5.1.1 Conversion of a standard c
25、urrent input signal to the standard voltage input signal may employ a resistor of 250 ohms 0.25 ohms having a temperature coefficient of not over 0.01%/C. 5.1.2 Receivers of less than 1 to 5 volt range can be operated from a tap on such a resistor as long as the receiver is designed with a live zero
26、 which is at 20% of full scale. 5.1.3 A voltage receiver shall not alter the voltage drop across the standard 250 ohm input resistor by more than 4 mV. 5.1.4 Receivers shall not be damaged by an input of 10 volts or 40 mA, whichever is applicable. 5.1.5 Receivers may have less than 250 ohms resistan
27、ce provided that they shall not be connected to signal common if a standard voltage signal for other receivers must also be developed from the same input current. 5.2 Outputs 5.2.1 When a dual independent current and voltage output signal are both provided by a receiver (such as controller), the loa
28、d applied to the current output terminals can be required to be a fully isolated type. 5.2.2 The peak to peak ripple and total noise level shall not exceed 0.25% of the maximum signal. This is further defined as not exceeding 10 mV peak to peak on a 5 volt signal (derived by resistive drop from a 20
29、 mA signal, or a voltage signal) when measured at the output of a 10 Hz low pass, single stage R-C filter and when operated from a dc test power source having the maximum allowed ripple and noise permitted in 6.5.2, or its normal ac power supply. (See Annex A.) ANSI/ISA-50.00.01-1975 (R2012) - 16 -
30、5.3 Isolation Isolation of receivers shall be determined and specified in accordance with the terminology of 4.5, Electrical isolation. (Refer to Figure A.1 for illustrations of the various isolation categories. Also see Annex A.) 6 System 6.1 Signal common Signal common for the system will be speci
31、fied as follows: 6.1.1 For systems in which transmitters of type 2 and 3 are used, the circuit common, if any, shall be the negative terminal of the power supply and receiver signal. (See Figure 1 and Annex A.) 6.1.2 For systems in which transmitters of type 4 are used, with dc power supplies, the n
32、egative terminal of the power supply will be connected to circuit common. (See Figure 1 and Annex A.) NOTE It is expected that circuit common will be earth grounded rather than left floating. See Annex A. 6.2 Power supplies 6.2.1 It is not, at present, the intent of this standard to define, specify,
33、 or standardize upon power supplies. The need for standard test power sources is recognized so as to provide a common reference for evaluation of transmitter and receiver performance. 6.2.2 To comply with the most generally accepted standards for personnel safety, power supplies should be limited to
34、 an upper level of 42.4 volts dc or 30 volts rms ac (whose peak value is 42.4 volts). 6.2.3 When ac powered equipment is designed for other than line voltage, a nominal 24 volts rms (+10 to 15%) is recommended. (See Annex A.) 6.3 Transmitters Transmitters of types 2, 3, and 4 may be expected to shar
35、e a common dc power supply or be connected to individual power supplies. 6.3.1 Type 4 transmitters, when designed for ac operation, should employ the recommended nominal values stated in 6.2.3. 6.4 Receivers or signal processors Receivers or signal processors may share a common dc power supply, or b
36、e operated from individual internal power supplies receiving their energy from ac power lines, or may receive a portion of their energy from both dc and ac power sources. 6.4.1 Receivers, when designed for ac operation, should employ the recommended nominal values stated in 6.2.3. 6.5 Test power sou
37、rces 6.5.1 The standard dc test power source shall be variable between the limits of 23 volts and 42.4 volts. 6.5.2 The ripple and other noise, peak to peak shall not exceed 1.0 percent of the test voltage when measured at the output of a 120 Hz single stage low pass R-C filter. - 17 - ANSI/ISA-50.0
38、0.01-1975 (R2012) 6.5.3 The standard test power source for low voltage ac powered instruments shall be a nominal 24 volt rms (+10 to 15%), 50 or 60 Hz. This page intentionally left blank. - 19 - ANSI/ISA-50.00.01-1975 (R2012) Annex A Supportive information This annex is intended to provide supportiv
39、e information for the clauses and subclauses of the standard designated. 4.3.2 Load resistancegeneral purpose applications: The 300 and 800 ohm values represent a commonly adequate need for receivers and line resistance drops. Many transmitters will have significantly greater load resistance capabil
40、ity. Additional capability permits the use of other instruments and accessory devices which may be necessary or desirable to use in specific control loops. 4.3.2 Load resistanceintrinsically safe applications: A basic requirement for intrinsically safe applications is that the transmitter/power supp
41、ly combination has sufficient load capability so as to permit the addition of the necessary current and voltage limiting to the loop. Many standard transmitter/power supply combinations will have such capability. Detailed specifications for intrinsic safety are beyond the scope of this document. 4.3
42、.2.1 The class L parameters were determined from the following considerations: Transmitter minimum drop 12.0 volt Receiver drop (250 ohms) 5.0 volt Line drop (50 ohms) 1.0 volt Intrinsic Safety Resistor (250 ohms) 5.0 volt Total 23.0 volt This document recognizes that many systems have already been
43、designed for use with a 24 volt nominal or minimum power supply voltage value, and is not suggesting that 23 volts is a necessarily desirable minimum voltage to which all systems should comply. 4.3.2.2 The 32.7 volt supply for class H was determined by the consideration that a usual tolerance for an
44、 unregulated power supply is about +10 percent, 15 percent. If its upper limit is held to 42.4 volts for personnel safety, the lower limit calculates to be 32.7 volts. The 800 ohms resistance is obtained by considering that the extra 10 volts (approx.) allows 500 ohms additional loop resistance. Min
45、imum voltage means minimum available in the loop with system fully loaded and minimum power line voltage or a nearly discharged battery. Line drop in a common low voltage distribution system including fuses, circuit breakers, etc. must be taken into account. 4.4.1 and 4.4.2 Load resistance The trans
46、mitter load resistance capability will decrease by 50 ohms for each 1 volt reduction in the power supply. Similarly, it will increase by 50 ohms per volt increase in the power supply, but must not exceed the safe voltage capability of the transmitters. 4.5 and 5.3 Signal isolation This document assu
47、mes that future instrument systems including receivers may share a common power supply between several instrument loops and that their signal common may be interconnected and referenced to earth ground. To avoid “ground loop“ errors, compliance with the following isolation requirements is essential
48、unless signal isolators, individual floating power supplies or other special engineering techniques are employed. ANSI/ISA-50.00.01-1975 (R2012) - 20 - a) When grounded electrical input sensors are to be employed, type 2 and 3 transmitters should be specified as “input isolated“ and type 4 transmitt
49、ers should be specified as “fully isolated.“ b) When ungrounded electrical input sensors are to be employed, type 2 and 3 transmitters may be specified as “non-isolated,“ but “input isolated“ designs provide more protection against an input ground which might subsequently occur. Type 4 transmitters should be specified as either “power isolated“ or “input isolated,“ while again “fully isolated“ provides the maximum protection against subsequent grounding faults. c) In no event should transmitters with “grounded output“ per 4.5.7 be connected to grounded receivers. They r
