Temperature Sensors and LST Networks Vishay Micro-Measurements Special Purpose Sensors - Temperature Resistance thermometry is a widely employed method of measuring temperature, and is based on using a material whose resistivity changes as a function of temperature. Resistance Temperature Detectors (RTD's) have fast response time, provide absolute temperature measurement (since no reference junctions are involved), and are very accurate. Their measurement circuits are relatively simple, and the sensors, when properly installed, are very stable over years of use. Vishay Micro-Measurements resistance temperature sensors are constructed much like wide-temperature-range strain gages. The standard sensors utilize nickel or nickel/ manganin grids, although special-purpose gages are also available in Balco (R) alloy or copper foil grids. These temperature sensors are bonded to structures using standard strain gage installation techniques, and can measure surface temperatures from -452 to approximately +500F (-269 to +260C). Because of their extremely low thermal mass and the large bonded area, the sensors follow temperature changes in the structural mounting surface with negligible time lag. Balco is a trademark of the W.B. Driver Company TG TEMPERATURE SENSORS TG Temperature Sensors are normally selected for measurements from -320 to +500F (-195 to +260C). The sensing grid utilizes a high purity nickel. Three basic constructions are offered: ETG Sensors have a polyimide carrier for flexibility. It is available as an encapsulated gage with exposed solder tabs (Option E), or with integral printed-circuit terminals (Option W). The WTG Sensor incorporates integral leadwires and a high-temperature epoxy-phenolic matrix (reinforced with glass fiber) which fully encapsulates the grid. The WWT-TG Sensor is a slightly larger version of the WTG, but preattached to a 0.005-in (0.13-mm) thick stainless steel shim. This gage can be welded or bonded to a structure. The resistance at +75F (+23.9C) is 50 0.3% for the ETG and WTG Sensors; and 50 0.4% for the WWT-TG Sensors. Maximum operating temperature for ETG Sensors with Option E is +450F (+230C), and +350F (+175C) for Option W. All other types are +500F (+260C). TEMPERATURE SENSOR SELECTION DIMENSIONS GAGE PATTERN AND DESIGNATION Approximate Size Shown ETG-50A/Option ETG-50A/Option ETG-50B/Option ETG-50B/Option E W E W 50A/E 50B/E Opt W Feature WTG-50A WTG-50A/Option W WTG-50B WTG-50B/Option W 50A 50B Opt W Feature WWT-TG-W200B-050 For weldable temperature sensor, see appropriate datasheet inches millimeters MATRIX Length Width GAGE LENGTH OVERALL LENGTH GRID WIDTH OVERALL WIDTH 0.060 0.148 0.100 0.100 0.28 0.20 1.52 3.76 2.54 2.54 7.0 4.8 0.125 0.235 0.125 0.125 0.33 0.19 3.18 5.97 3.18 3.18 8.3 4.7 0.060 0.148 0.100 0.100 0.28 0.20 1.52 3.76 2.54 2.54 7.0 4.8 0.125 0.235 0.125 0.125 0.33 0.19 3.18 5.97 3.18 3.18 8.3 4.7 0.20 (shim length) 0.71 0.200 (shim width) 0.43 0.52 0.26 5.08 18.03 5.08 10.92 13.1 6.6 In addition to the standard line of temperature sensors described above, Vishay Micro-Measurements can furnish almost any type of sensor pattern desired, in a wide range of resistances. Contact our Applications Engineering Department for details. www.vishaymg.com 100 micro-measurements@vishay.com Document Number: 11522 Revision 03-Sep-03 Temperature Sensors and LST Networks Vishay Micro-Measurements Special Purpose Sensors - Temperature Temperature in C -100 0 TG LST MATCHING NETWORKS +100 The temperature coefficient of resistance of nickel sensors is very high but nonlinear as indicated in the graph. The sensor resistance can be measured directly and converted to temperature with the charts supplied in Tech Note TN-506, but since TG Sensors are commonly used along with strain gages, special matching networks have been developed to use with strain gage instrumentation. +200 140 130 120 These LST Matching Networks are small passive devices encapsulated in a molded epoxy case. They are connected between TG Temperature Sensors and the strain gage readout instrumentation to perform the following three functions: 110 100 1. Linearize the gage resistance versus temperature. 90 2. Attenuate the resistance change slope to the equivalent of 10 or 100 microstrain per degree F or C for a gage factor setting of 2.000 on the strain indicator. 80 60 TG Sensor 50 @ +75F (+23.9C) 50 4 3 5 2 Active Dummy 1 40 Strain Indicator 3. Present a balanced 350-ohm half-bridge circuit to the strain indicator at the reference temperature of 0F (Fahrenheit networks) or 0C (Celsius networks). 70 LST NETWORK 30 20 10 -200 -100 0 +100 +200 +300 +400 +500 Temperature in F In order to optimize performance, separate network designs are available for cryogenic and normal temperature ranges. Environmental temperature range of LST networks is -65 to +250F (-55 to +125C). Standard strain gage instrumentation, such as the Vishay Micro-Measurements Model P3500, is ideal for use with these sensors, eliminating the need to purchase separate readout devices. Typical data for 50 nickel sensor. NORMAL TEMPERATURE RANGE LOW TEMPERATURE RANGE NETWORK DESIGNATION LST-10F-350C LST-10C-350C LST-100F-350C LST-100C-350C OUTPUT SLOPE 10 microstrain/F 10 microstrain/C 100 microstrain/F 100 microstrain/C Document Number: 11522 Revision 03-Sep-03 SENSOR TEMPERATURE RANGE -320 to +100F -200 to +25C -320 to +100F -200 to +25C NETWORK DESIGNATION LST-10F-350D LST-10C-350D LST-100F-350D LST-100C-350D micro-measurements@vishay.com OUTPUT SLOPE 10 microstrain/F 10 microstrain/C 100 microstrain/F 100 microstrain/C SENSOR TEMPERATURE RANGE -200 to +500F -150 to +260C -200 to +500F -150 to +260C www.vishaymg.com 101 Temperature Sensors and LST Networks Vishay Micro-Measurements Special Purpose Sensors - Temperature CLTS-2B TEMPERATURE SENSORS The Cryogenic Linear Temperature Sensor (CLTS) is recommended for best accuracy over the temperature range of - 452 to +100F (-269 to +40C). The CLTS-2B is a small surface thermometer gage consisting of two thin foil sensing grids laminated into a glass-fiber-reinforced epoxy-phenolic matrix, and electrically wired in series. The two alloys are special grades of nickel and manganin that are processed for equal and opposite nonlinearities in resistance versus temperature characteristics. The CLTS-2B is fabricated with integral printed-circuit terminals to provide strong, convenient attachment points for the leadwires. Gage construction is illustrated at right. Because of its low thermal mass and thin construction, the CLTS-2B responds quickly and accurately to temperature changes in the surface to which it is bonded. Special design features protect the sensor from damage due to thermal shock, even during plunges from room temperature directly into liquefied gases, including LHe at -452F (-269C). Avoid prolonged exposure of the CLTS-2B to temperatures above +150F (+65C) as this may adversely affect characteristics of the manganin material. The maximum recommended curing temperature of the bonding adhesive is two hours at +200F (+95C). CLTS-2B SENSITIVITY The nominal resistance of the CLTS-2B is 290.0 ohms 0.5% at +75F (+23.9C). The resistance decreases linearly with temperature, reaching a nominal value of 220.0 ohms at -452F (-269C). This represents a change of 70 ohms for 527F, or a slope of 0.1328 ohms per degree F; the corresponding slope on the Celsius scale is 0.2391 ohms per degree C. With proper instrumentation a resolution of 0.01 can be easily achieved. Data readout can be accomplished by directly monitoring resistance change with an appropriate resistance measuring instrument. DIMENSIONS GAGE PATTERN AND DESIGNATION Actual size shown. CLTS-2B MATRIX GAGE LENGTH OVERALL LENGTH GRID WIDTH OVERALL WIDTH Length Width 0.130 0.205 0.280 0.280 0.43 0.31 3.30 5.21 7.11 7.11 10.9 7.9 CLTS MATCHING NETWORKS When used in conjunction with bonded strain gages, it is often most convenient to modify the CLTS output with a simple, passive resistance network that can be used with strain gage instrumentation as described with the TG Sensors. The sensitivity can be www.vishaymg.com 102 adjusted to 10 microstrain per degree F (CLTS-N-F) or C (CLTS-N-C); with a resolution of 0.1 when used with most strain indicators. This type of network also provides a high degree of leadwire compensation. Environmental temperature limits for CLTS Networks are -65 to +250F (-55 to +125C). micro-measurements@vishay.com Document Number: 11522 Revision 03-Sep-03