Newnes Sensor Technology Handbook 2005 Yyepg Lotb Part 16 potx

This page intentionally left blank 591 A P P E N D I X A Lifetime Cost of Sensor Ownership Analyzing It, Calculating It Overview “There is nothing in the world that some man cannot make a little worse and sell a little cheaper, and he who considers price only is that man’s lawful prey.” —John Ruskin (1819−1900) The lifetime cost of a sensor or transducer involves more than the initial cost for the item itself. By looking at the total cost of ownership, an optimum purchase decision can be made specific to your application. Introduction If you purchase a car, the initial purchase price may only be 60% of the total lifetime cost of the vehicle. Gas, oil, repairs, insurance, maintenance, taxes, license fees, and other costs can exceed the initial purchase price over a 5- to 10-year typical vehicle lifetime. If your company purchases a PC, the initial purchase price may only be 10% of the total lifetime cost of the computer. Installation, support, training, upgrades, and re- pairs usually dwarf the initial outlay. Have you looked at the total cost of ownership for the sensors and transducers you are using? Do you look at these costs before making a specification? Typical “Initial Cost” Purchase Analysis When someone asks you how much did something “cost,” you typically state a figure based on what was shown on the quote, invoice, or receipt. In the case of a transducer, this is often only the cost of the transducer and possibly an amount for shipping, taxes, and related transaction costs. 592 Appendix A This cost accounting may make the boss and the finance department happy. It can also reduce effectiveness and profitability. What’s Missing You may say to yourself, “I’m only buying a simple transducer. What other costs could there be?” I’m glad you asked. Below is a list of other costs that you may incur in the purchas- ing, maintaining, installing, and use of your transducer. These costs, in total, can become much larger than the initial “invoice” purchase price. Installation. Does the transducer design require you to make a special mounting plate or is flexible mounting inherent in the product? How long does installation take? Can installation be performed by a lower-skilled employee or must a higher- skilled technician or engineer perform the task? Cabling, Connectors, and Signal Conditioning. Does the sensor require the pur- chase of additional electrical cable, electrical connectors, signal conditioning, and related instrumentation? Reliability. What is the stated lifetime of the product? Does it have an MTBF (mean time before failure) rating? Does the vendor have reliability statistics of the product being used in an environment similar to your own? Unscheduled downtime costs can be huge in factory automation, aviation, and capital-inten- sive applications. Scheduled Down Time. Is calibration or scheduled maintenance required? How will this downtime affect your operations? Will alternate sensors need to be installed? Can this work be done during other maintenance periods? Repairs. Is the product repairable or is it discarded at the end of its lifetime? Are there costs associated with its disposal? Can the repair be performed on site or must the item be returned to the manufacturer? Calibrations. Can calibrations be performed on site or is factory return required? How often are calibrations required and what is the cost? Usability. Is the signal from the product easy to work with or does it require special- ized power supplies, amplifiers, and related equipment that must be procured, installed, learned, and configured? 593 Lifetime Cost of Sensor Ownership Lead Time. Longer lead times require you to spend more time scheduling and may require you to stock sensors to avoid stock out situations. On-time Performance. Does the sensor get delivered on time? If you planned for receiving the item in 7 days but the shipment does not show up for 21 days, you will spend valuable time re-scheduling resources and nagging the vendor to get the product to you. Environmental Rating. Unintended uses can often make environmental protection an important feature. A misplaced cup of coffee or an inadvertent blow from a steel- toed shoe can wreak havoc on your “office environment” sensor. And increase your costs. And if you plan to add environmental protection yourself, remember to add this cost to the solution’s total cost. Shipping. It may not seem like much to pay a flat small fee for shipping. But add that flat small fee over spare parts, factory calibrations, repairs, and replacements and the amount can become substantial. If shipping is based on weight and volume, look at the products you are consid- ering specifying. Are there any size or weight differences? Are there are tariff differences related to the products originating from different countries? Stocking Requirements. Lead time, reliability, repairability, ontime shipping and other factors influence the stocking (inventory) levels required for the transducer. A rule of thumb is that annual inventory carrying costs are 25% with ranges from 18% to 75%. Your carrying costs may be higher than 25% based on this analysis: Cost of Money 6 to 12% Taxes 2 to 6% Insurance 1 to 3% Warehouse Expenses 2 to 5% Physical Handling 2 to 5% Inventory Control 3 to 6% Obsolescence 6 to 12% Deterioration and Pilferage 3 to 6% Recalibration 5 to 10% Total 30 to 65% To reiterate, the above are annual carrying costs that will continue as long as you hold the products in your inventory. 594 Warranty. What is the length of warranty? What are the terms of the warranty? Are extended warranties available? What are the warranty restrictions? Training. Are there extraordinary education or training requirements to use the sensor and related instrumentation? Is calibration straightforward is a course required? Documentation. Are adequate user manuals and application notes available? Do us- ers need to spend valuable time learning and documenting the product? Customer Service. Is customer service readily available? What are the hours of op- eration? How responsive is customer service to your inquiries regarding pricing, shipping information, and repairs? Is Web site pricing and ordering available? Technical Support. Is technical support available 24/7/365? Are there fees associ- ated with technical support? Is the information provided complete, accurate, and timely? Still Not Convinced? Do you believe total cost of ownership is not relevant in your application? Consider the experience of an airline who went with “an affordable” choice only to find out 15 months later that the transducers were surviving for only 12 months on average and needed to be replaced annually. The replacement transducer selected did cost 20% more but was available off-the-shelf and was previously qualified for aircraft use. There have been no failures with the replacement transducers and no replacements have been required after 36 months of continuous use. The Bottom Line To do an interactive comparison of sensor and transducer total lifetime costs, use the Total Cost of Ownership Calculator at http://spaceagecontrol.com/calctco.htm. Conclusion The selection of the proper sensor or transducer for a given application includes an evaluation of the costs of the sensor or transducer. Initial purchase costs can be less than 20% of the product’s lifetime costs. Only by considering the lifetime costs can you ensure you are specifying an optimum solution. Appendix A 595 Lifetime Cost of Sensor Ownership References and Resources: 1. For an analysis on downtime costs, see The Hidden Cost of Downtime (Smart- Signal Corporation). 2. Richardson, Helen: Transportation & Distribution, “Control Your Costs Then Cut Them,” December 1995. This page intentionally left blank 597 A P P E N D I X B Smart Sensors and TEDS FAQ 1. What is IEEE 1451? IEEE 1451 is a set of standards that were established to address smart sensor systems and to develop a comprehensive set of sensor and software protocols. It was hoped that the standard would pave the way for seamless connection of many parts of smart sensors and associated hardware and software. 2. What is IEEE 1451.2? The first of these standards was IEEE 1451.2. The standard was designed to gain a standard way to specify the device operation and calibration, a standard physi- cal interface between the sensor and the communications device, and the ability to use standardized off-the-shelf components to build smart sensors. IEEE 1451.2 had considerable challenges that ultimately led to virtually no adoption of it in practical applications. 3. What is IEEE 1451.4? IEEE 1451.4 directs its attention to only the TEDS part of the sensor and signal conditioning system. IEEE 1451.4 adopts a valuable approach by taking a much more simple approach to other smart sensor concepts by simply focusing on the self-identification aspects of a sensor. IEEE1451.4 does this by specifying a table of self-identifying parameters that are stored in the sensor in the form of a TEDS (Trans- ducer Electronic Datasheet). 4. What is P1451.4? The IEEE1451.4 committee have only published a draft specification. All indications are that the standard will change slightly before it is published in its final format. National Instruments and its sensor partners have decided not to wait for the final ver- sion and are suggesting that sensor vendors start producing sensors based on the draft specification. The draft specification is defined as P1451.4 for (P)reliminary release, to separate it from the eventual 1451.4 specification. 598 Appendix B 5. What is TEDS? TEDS is an acronym for Transducer Electronic Datasheet. It is a table of parameters that identify the transducer and are held in the transducer on a EEprom for inter- rogation by external electronics. The definition of the table is still not fully defined by the IEEE committee so carries the designation IEEE P 1451.4 for preliminary. Note: TEDS is the data contained on a sensor that is defined by IEEE1451.4. Honey- well Sensotec has for the last 8 years used the TEDS concept in its SIG CAL or SIG MOD. This TEDS in the SIG CAL Plug and Play technology is defined by Honeywell Sensotec rather than the IEEE1451.4 standard. 6. What data is carried in 1451.4 TEDS? There are four areas of TEDS data. One is the basic data that identifies the transducer. The EXTENDED TEDS is where all the electrical and physical properties are stored. The USER area is where a sensor user can store data regarding the sensors location, next calibration date etc. The TEMPLATES section has yet to be fully defined by the IEEE1451.4 committee but will likely contain additional data that is distinct for each class of sensor and will be compiled by the manufacturer. An example of this might be the calibration curve for a ASTME74 load cell. Basic TEDS Standard and Extended TEDS User Area Templates Manufacturer ID Sensotec Model Number 41 Serial Number 462992 Version Letter 53e Calibration Date April 22, 2002 Temperature effect on span 0.0045 Temperature effect on offset 0.0045 Min Operating Temperature -53 Max Operating Temperature 121 Response Time 0.0005 Min Electrical Output -2 Max Electrical Output +2 Sensitivity 1.998 Bridge Impedance 350 Excitation Nominal 10 Excitation Maximum 15 Excitation Minimum 3 Max Current Draw 30 Sensor Location 23 right dyno Calibration Due Date April 21, 2003 Special Calibration Date 12.3-0 175x-0.00 Wiring Code Wiring Code #15 Transducer Electronic Data Sheet TEDS [...]... Pa 603 multiply by 0.3048 4047 9.294E-02 1.000E+04 6.452E-04 1000 16. 02 2.767E+04 1.069E+07 515.40 1055 4.1859 1.000E-07 1.602E-19 1.3557 4.187E+12 3.600E+06 4.187E+15 1.000E-05 4.4484 0.2780 4188 5.6786 1.496E+11 0.3048 2.540E-02 160 9 1853 3.085E +16 1.661E-27 0.4535 1200.00 14.59 1.260E-04 0.4535 1.3557 0.1130 7.062E-03 0.2931 745.71 3 516 1.000E+05 0.1000 3377 248.82 9.807E+04 47.89 divide by 3.2810... data once the signal conditioning has read the information off the EEprom It is up to sensor manufacturers to use the dot 4 standard either passively or actively Honeywell Sensotec has chosen to use the IEEE1451.4 table actively and provides ‘Plug, Play and Calibrate’ of the sensor and signal conditioning system Sensor analog output 1010010100101010 1010101000101010 1110111001011101 1010101010100001...Smart Sensors and TEDS FAQS 7 What is the output of a TEDS sensor? There are two types of TEDS sensor outputs: four wire outputs or two wire outputs/ two wire ICP outputs (Integrated Charge Pump) used on accelerometers In the case of four wire systems... Benzene (0°C) Carbon tetrachloride (0°C) Glycerin (0°C) Kerosene (0°C) Mercury (0°C) Oil - light machine (0°C) Water (0°C) 623 0.6000 2.2000 0.5200 0.5200 0.2300 1.1000 16. 27 46.73 53.65 7.4420 164 .40 0.6030 0.1100 22.68 24.30 24.66 14.94 2.8000 16. 56 4.39 52.74 26.10 25.20 5.4000 12.96 9.0000 4.0000 5.0000 19.80 17.82 11.34 6.4800 9.3600 4.5000 1.708E-05 1.390E-05 1.860E-05 8.345E-06 1.026E-05 1.660E-05... Interrogates table and sets instrument up ready to go Sensotec Plug Play and Calibrate 8 What is Plug and Play? Plug and Play is the name adopted for the technology surrounding IEEE1451.4 Plug and Play, however, suggests that the user can plug the sensor into the signal conditioning and everything is automatically configured and is ready to take measurements The IEEE1451.4 standard does not explicitly... 2.1 2.9 - 4.5 4.5 1.00000 Dielectric Strength (V/mil) 600 Max Temp (°F) 800 400 200 200 450 280 450 - 990 450 - 1200 170 500 500 725 40 -280 335 150 - 200 250 150 - 500 170 100 - 700 300 140 550 616 480 1560 2 .16 2.8 - 4.5 88.0 80.4 55.3 76.7 - 78.2 1.2 - 2.1 1000 400 80 APPENDIX F Index of Refraction Material Vacuum Air at STP Ice Water at 20 C Acetone Ethyl alcohol Sugar solution(30%) Fluorite Fused... HK31A-H24 Molybdenum - wrought Nickel - pure Platinum Silver - pure Steel AISI 304 621 1047 544.00 2547 293.00 461.00 130.00 1300 1340 937.00 235.00 503.00 419.00 126.00 544.00 138.00 4 216 55.70 47.70 25.50 334.00 1368 162 .76 23.93 451.90 577.40 87.03 199.20 2258 5.6000 18.90 38.00 1.800E-05 1.121E-07 1.753E-06 0.3300 0.3300 0.3300 0.0300 0.1950 0.2200 0.4200 0.4200 0.3500 0.3500 0.3200 0.3900 0.3700... The IEEE1451.4 standard was written around the same EErom as utilized by the Honeywell Sensotec ‘Sig Cal’ Conversion of a Sig Cal sensor to IEEE1451.4 requires a software change only The IEEE 1451.4 defines a passive system only where the table of data that resides in the sensor ‘Sig Cal’ on the other hand uses a Honeywell Sensotec defined table of data and then uses that data to set up the SC2000 so... 0.1000 3377 248.82 9.807E+04 47.89 divide by 3.2810 2.471E-04 10.7600 1.000E-04 1550 1.000E-03 6.243E-02 3.614E-05 9.357E-08 1.940E-03 9.478E-04 0.2389 1.000E+07 6.242E+18 0.7376 2.388E-13 2.778E-07 2.388E -16 1.000E+05 0.2248 3.5968 2.388E-04 0.1761 6.685E-12 3.2810 39.3700 6.214E-04 5.397E-04 3.241E-17 6.022E+26 2.2050 5.711E-03 6.853E-02 7937 2.2050 0.7376 8.8510 141.60 3.4120 1.341E-03 2.844E-04 1.000E-05... wrought Nickel - pure Platinum SiC Alpha SiC sintered KT Silver - pure Steel AISI 304 Steel AISI C1020 Tantalum Titanium B 120VCA Tungsten Aluminum 2017 Aluminum 3003 Aluminum 99.996% Copper Nickel ASTM B160 Steel AISI 304 Steel AISI C1020 Air Aluminum 2024-T3 Aluminum 6061-T6 Aluminum 7079-T6 Beryllium QMV Borosilicate glass Concrete Copper - pure Dow Corning 200 (350 cST) Ethanol (25°C) Gold - pure Ice . format. National Instruments and its sensor partners have decided not to wait for the final ver- sion and are suggesting that sensor vendors start producing sensors based on the draft specification X B Smart Sensors and TEDS FAQ 1. What is IEEE 1451? IEEE 1451 is a set of standards that were established to address smart sensor systems and to develop a comprehensive set of sensor and software. attention to only the TEDS part of the sensor and signal conditioning system. IEEE 1451.4 adopts a valuable approach by taking a much more simple approach to other smart sensor concepts by simply