1、Specifications and Tests for Strain Gage ForceTransducersReaffirmed 29 September 1995ISA37.81982 (R1995)Formerly ISAS37.81982 (R1995)STANDARDISA The Instrumentation,Systems, andAutomation Society TMCopyright 1982 by the Instrument Society of America. All rights reserved. Printed in the UnitedStates
2、of America. No part of this publication may be reproduced, stored in a retrieval system, ortransmitted in any form or by any means (electronic, mechanical, photocopying, recording, orotherwise), without the prior written permission of the publisher.ISA67 Alexander DriveP.O. Box 12277Research Triangl
3、e Park, North Carolina 27709ISA-37.8-1982 (R1995) Specifications and Tests for Strain Gage Force TransducersISBN 0-87664-381-0ISA-S37.8-1982 (R1995) 3PrefaceThis preface, as well as all footnotes and annexes, is included for informational purposes and is not part of ISA-37.8-1982 (R1995).This Standa
4、rd has been prepared as a part of the service of ISA, the international society for measurement and control, 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 wel
5、comes 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 Depar
6、tment 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, recommended practices, and technical reports. The Department is further aware of the benefits to USA u
7、sers of ISA Standards of incorporating suitable references to the SI (and the metric system) in their business and professional dealings with other countries. Towards this end, this Department will endeavor to introduce SI and acceptable metric units in all new and revised standards to the greatest
8、extent possible. The Metric Practice Guide, which has been published by the Institute of Electrical and Electronics Engineers as ANSI/IEEE Std. 268-1992, and future revisions, will be the reference guide for definitions, symbols, abbreviations, and conversion factors.It is the policy of ISA to encou
9、rage and welcome the participation of all concerned individuals and interests in the development of ISA standards, recommended practices, and technical reports. Participation in the ISA standards making process by an individual in no way constitutes endorsement by the employer of that individual, of
10、 the ISA, or of any of the standards which ISA develops.This Standard is intended as a guide for technical personnel at user facilities as well as by manufacturers technical and sales personnel whose duties include specifying, calibrating, testing, or showing performance characteristics of strain-ga
11、ge linear accelerometers. By basing users specifications as well as technical advertising and reference literature on this Standard, or by referencing portions thereof, as applicable, a clear understanding of the users needs or of the transducers performance capabilities, and of the methods used for
12、 evaluating or proving performance, will be provided. Adhering to the specification outline, terminology and procedures shown will not only result in simple, but also complete specifications; it will also reduce design time, procurement lead time, and labor, as well as material costs. Of major impor
13、tance will be the reduction of qualification tests resulting from use of a commonly accepted test procedure and uniform data presentation.The development of this Standard was initiated as the result of a survey conducted in December 1960. A total of 240 questionnaires was sent out to transducer user
14、s and manufacturers. A strong majority indicated in their replies a need for transducer standardization. As strain-gage force transducers were one of the types shown to be most in need of standardization, a Subcommittee, SP37.8, was formed. To provide a coordinated document, this committee was compo
15、sed of representatives from government, user and manufacturer categories. This Standard was then processed over several mail-review and revision cycles until a consensus of reviewers was reached.4 ISA-S37.8-1982 (R1995)The following individuals served on the 1975 SP37.8 committee:NAME COMPANYJ. J. E
16、lengo, Jr. Chairman Revere Corporation of AmericaP. F. Fuselier Lawrence Radiation LaboratoryR. E. Gorton Pratt bonded or unbonded, wire or foil; Semiconductor; bonded or unbondedd) Location of Strain-Gage Mounted directly on force sensing element or mounted on auxiliary member activated by force se
17、nsing element12 ISA-S37.8-1982 (R1995)e) Number of Active Strain-Gage Bridge Arms (elements)f) One, Two-arm active, Four-arm bridgeg) Number of Strain-Gage Bridges h) Mounting Surface Requirements4.1.3 Basic electrical design characteristicsThe following electrical design characteristics shall be li
18、sted. They are applicable at “ambient conditions“ as specified in 4.2.4.1.3.1 Excitation* Expressed as “_ volts dc“ or “_ volts rms at _ Hz,“ or, expressed as “_ mA dc“ or “_ mA rms at _ Hz.“ Preferred values of voltage 5, 10, 15, 20, and 28 volts.4.1.3.2 Maximum excitation* Expressed as “ _ volts d
19、c“ or “_ volts rms at _ Hz,“ or, expressed as “_ mA dc“ or “_ mA rms at _ Hz,“ and defined as the maximum value of excitation voltage that will not permanently damage the transducer.4.1.3.3 Input impedance* Expressed as “_ _ ohms at _ _ Hz“ and “_C (F).“ If impedance is resistive, specify “dc.“ NOTE
20、 Output terminals are to be open-circuited for this measurement.4.1.3.4 Output impedance* Expressed as “ _ _ ohms at _ _ Hz“ and “_ C(F) .“ If impedance is resistive, specify “dc.“ NOTE If input terminals are to be short-circuited for this measurement, so specify.4.1.3.5 Electrical connectionsWhethe
21、r the electrical termination is by means of a connector or a cable, the pin designation or wire color code shall conform to the following:*Defined in ISA-S37.1ISA-S37.8-1982 (R1995) 13:NOTES1. The output polarities indicated on the above wiring diagram apply when an increasing force (compression or
22、tension) is applied to the transducer. For universal force transducers, the indicated polarities apply when the tension force is applied to the transducer; a compression force will produce a negative output.2. For shielded transducers, pins 5, 7, and 9 shall be shield terminals for 4, 6, and 8 wire
23、systems, respectively.3. Type connection: Solder or weld.4.1.3.6 Insulation resistance Expressed as “_ megohms at _ volts dc at _ C(F) between all terminals or leads connected in parallel, and the transducer case.“4.1.4 Supplemental electrical design characteristicsListing of the following design ch
24、aracteristics is optional.4.1.4.1 Shunt calibration resistor(s) Expressed as “_ _ ohms for _ % _% of full scale output at _C(F).“NOTE The terminals across which the resistor(s) is (are) to be placed shall be specified if the resistor(s) is (are) listed.12 34W= WHITER=REDW-R = WHITE-REDW-G = WHITE-GR
25、EENG=GREENW-B = WHITE-BLACKB=BLACKW-Y = WHITE-YELLOW7/G9/I SHEILD (FLOATING)4/D -INPUT8/H2/B +OUTPUT6/F5/E1/A +INPUT3/C -OUTPUTCONNECTORPrimary wiring terminals1/A,2/B,3/C,4/DAuxiliary wiring terminals 5/E, 6/F, 7/G, 8/H( Optional)14 ISA-S37.8-1982 (R1995)4.2 Performance characteristicsThe pertinent
26、 performance characteristics of strain-gage force transducers shall be tabulated in the order shown. Unless otherwise specified, they apply at the following ambient conditions:Temperature 23 2C (73.4F 3.6F); Relative Humidity 90% maximum; Barometric Pressure 98 10 kPa (29 3 inches of Hg).4.2.1 Range
27、* Usually expressed as “_ to _ newtons (pounds force) compression or tension“ or “ _ to _ newtons (pounds force) compression and _ to _newtons (pounds force) tension.“NOTE If 4.2.2 and 4.2.3 are used to specify performance characteristics, the tolerance in 4.2.3 may be omitted. Alternately, the foll
28、owing may be specified: 4.2.3 - 4.2.6.4.2.2 End points*Expressed as “_ _ mV and _ _ mV open circuit per volt (mA) excitation,“ or “_ _ mV and _ _ mV open circuit at _ volts (mA) excitation.”4.2.3 Full Scale Output (FSO)* Expressed as “_ _ mV open circuit per volt (mA) excitation,“ or “_ _ mV open ci
29、rcuit at _volts (mA) excitation.“4.2.4 Zero-measurand output Expressed as “ _% of full scale output.“ Determined at full rated excitation, with zero measurand applied to the force transducer.4.2.5 Zero drift Expressed as “_ % of full scale output over a period of _ (specify time) with no load applie
30、d.“4.2.6 Sensitivity driftExpressed as “ _ % of full scale output over a period of _ (specify time) with _ newtons (pounds force) applied.“4.2.7 Linearity*Expressed as “ _ linearity within _% of full scale output in _ specify direction(s) of loading.“NOTE The type of linearity specified shall be one
31、 of the types defined in ISA-S37.1; namely, end point, independent, least squares, terminal, or theoretical slope.4.2.8 Hysteresis Expressed as “_% of full scale output upon application of ascending and descending forces including rated force.“ Alternately, 4.2.7 and 4.2.8 may be combined as follows
32、.*Defined in ISA-S37.1ISA-S37.8-1982 (R1995) 154.2.9 Hysteresis and linearity Expressed as “combined hysteresis and linearity within _% of full scale output upon application of ascending and descending forces including rated force.“4.2.10 Repeatability*Expressed as “within _% of full scale output ov
33、er a period of _ (specify time) and with _ cycles of load application.“Alternately 4.2.7, 4.2.8, and 4.2.10 may be combined as follows.4.2.11 Static error band Expressed as “ _% of full scale output as referred to _straight line,“ (see 4.2.7).NOTE The static error band includes errors due to lineari
34、ty, hysteresis, and repeatability.4.2.12 Creep at load Expressed as “ _ % of full scale output with the transducer subjected to rated force for a period of _ ( specify time).“4.2.13 Creep recovery Expressed as “ _ % of full scale output measured at no load and over a period of _ (specify time) immed
35、iately following removal of rated force, that force having been applied for an identical period of time as specified in 4.2.12.“4.2.14 Warm-up period* Expressed as “ _ minutes for subsequent drifts in sensitivity of zero-measurand balance not to exceed _% of full scale output.“4.2.15 Static spring c
36、onstantExpressed in newtons per meter or (pounds force per inch), see 6.3.4.2.16 Equivalent dynamic masses Expressed in kilograms (pounds mass), for both ends of transducer, see 6.3.4.2.17 Internal mechanical damping Expressed in newtons per meter/second relative velocity (pounds force per inch/seco
37、nd relative velocity), between ends at a frequency of _ Hz and a dynamic load of _newtons (pounds force).4.2.18 Overloading rating, safe Expressed as “application of_ newtons (pounds force) for_ minutes will not cause permanent changes in transducer performance beyond specified static error band.“4.
38、2.19 Rated force Expressed as “ _ newtons (pounds force) either compression or tension.“ This is the maximum axial force the transducer is designed to measure within its specifications.16 ISA-S37.8-1982 (R1995)4.2.20 Thermal sensitivity shift* Expressed as “ _% of sensitivity _ per C(F) temperature
39、change over temperature range from_ to _C (F).” 4.2.21 Thermal zero shift*Expressed as “ _% of full scale output per _C (F) temperature change over temperature range from _ to _C (F).“4.2.22 Temperature error band* Expressed as “output values are within _% of full scale output from the straight line
40、 establishing static error band (as defined in 4.2.11) over temperature range from _ to _C (F).“4.2.23 Temperature gradient error* Expressed as “less than _ % of full scale output while at zero load and subjected to a step function temperature change from _ to _C (F) lasting for _ minutes and applie
41、d to _ (specify particular part) of the transducer.“4.2.24 Cycling life Expressed as “ _ full scale cycles over which transducer shall operate without change in characteristics beyond its specified tolerances.“4.2.25 Other environmental conditions Other pertinent environmental conditions that shall
42、not change transducer performance beyond specified limits shall be listed. The following are examples:a) Shock Triaxialb) High Level Acoustic Excitationc) Humidityd) Salt Spraye) Electromagnetic Radiationf) Magnetic Fieldsg) Nuclear Radiation4.2.26 Storage life Expressed as “Transducer can be expose
43、d to specified environmental storage condition for _ (days, months, years) without changing the following performance characteristics beyond their specified tolerances.“NOTE Environmental storage conditions shall be described in detail. Pertinent perfor-mance characteristics (examples: sensitivity z
44、ero drift) shall be specified.*Defined in ISA-S37.1ISA-S37.8-1982 (R1995) 174.2.27 Abnormal loading effects (Refer to Figure 1.)4.2.27.1 Concentric angular load effect Expressed as “ _ % of full scale output difference from true output (axially loaded output multiplied by cosine of angle) resulting
45、from a load applied concentric with the primary axis at the point of application and at _ degrees angle with respect to the primary axis.“4.2.27.2 Eccentric angular load effectExpressed as “ _ % of full scale output difference from true output multiplied by cosine of angle) resulting from a load app
46、lied eccentric with the primary axis and at a _ degree angle with respect to the primary axis.“4.2.27.3 Eccentric load effect Expressed as “ _ % of full scale output difference from axially loaded output resulting from a load parallel to but displaced_ mm (in.) from concentricity with the primary ax
47、is.“4.3 Additional terminology4.3.1 ambient pressure effects: The change in sensitivity and the change in zero-measurand output due to subjecting the transducer to a specified ambient pressure change.4.3.2 creep at load: The change in output occurring with time under rated load and with all environm
48、ental conditions and other variables remaining constant.4.3.3 creep recovery: The change in zero-measurand output occurring with time after removal of rated load, which had been applied for an identical period of time as employed in evaluating Creep at Load.18ISA-S37.8-1982(R1995)Figure 1BB BECCENTRICITYECCENTRICITYL=LcosBL=LsinBasLLa BL LLFig.1a Fig.1b Fig.1cError =a 1/cosBaX100 Error =a 2/cosBaX100% RatedOutputError =a 3aX100RatedOutput% RatedOut
