Model 13-4615-47 Temperature Amplifier User`s Manual
Contents
1. 150 to 650 C Attenuator Steps 2 5 10 25 50 100 250 500 1000 degrees F S plus OFF Attenuator Inaccuracy 0 25 of calibrated step Sensitivity Vernier Multiplies full scale sensitivity by a minimum of 2 5 times Input Configuration Differential Floating from case Input Impedance 1 MQ minimum for DC to 10 Hz Common Mode Rejection DC greater than 140dB on most sens range w 3502 unbalanced 60 Hz greater than 120 dB on most sens range Maximum Allowable Input 260 volts RMS across input signal terminals Voltage without Damage 500 volts DC or Peak AC from common to chassis Zero Line Instability After 15 minute warm up With Time 05 C for 24 hrs With Temperature 04 degrees C ambient change With Line 2 of full scale for 10 line voltage change Gain Stability With Time 05 of reading 24 hrs With Temperature 03 of reading C With Line 1 of reading for 10 line voltage change Output Voltage 5V into 2 kQ or greater in parallel with O2u f or less Output Impedance lt 5Q Output Noise lt 2 of Full Scale P P DC to 100 Hz on most sens range decreasing on less sensitive ranges Non Linearity 55 C or 1 F or 2 whichever is greater over linearized range for 1000 RTD Frequency Response 3 dB down at 10 Hz 20 lower with plug in capacitors not supplied Filter Roll Off 18dB octave or 60dB decade Digital Panel Meter Output 10mV F or C 1000 degrees maximum 100mV F or C2. 100 degrees maximum Calibrated Zero Suppression Practical ration of suppression setting to attenuator setting 100 1 usable to 500 1 Range 0 to 999 degrees Resolution degree F or C Non Linearity 2 at suppression reading 05 Inaccuracy at 25 C nominal line 2 at suppression reading 05 Stability After 15 minute warm up With Time 015 of suppression range 24 hrs With Temperature 0125 of suppression range C With Line 01 of suppression range for 10 line voltage change Noise 02 PTP from DC to 100Hz Operating Temperature 0 C to 50 C 4 32 F to 122 F Operating Humidity 95 Storage Temperature 40 C to 70 C 40 F to 158 F Power Input Voltage DC and 15Vdc at 100ma Line Load Regulation 5 Ripple 5 millivolts RMS maximum RTD Current Excitation Steps 2ma at 1009 0 4 ma at 500 Q 0 2 ma at 1000 Q all at 0 C Copper RTD Operation Range 75 C to 150 C Linearity Within 2 C Nickel RTD Operation from 75 C to 150 C Range 60 to 180 C Linearity Within 2 C Thermistor Probe Operation internal switch selectable from 6 C to 180 C Range 0 to 42 C Linearity Within 5 C from 4 C to 40 C within 1 C from 0 C to 42 C Excitation Approximately 765 millivolts DC supplied internally 1 3 SUPPLIES AND ACCESSORIES Parts Supplied with the Preamplifier Input Connector Male Plug in Resistors R 42 4 5 KQ R 46 100 KQ R 50 225 KQ Optional Acc
3. 161 05 162 91 164 76 166 62 168 47 170 32 172 16 174 00 175 84 177 68 179 51 181 34 183 17 185 00 186 82 188 64 190 46 192 27 194 08 1255 1260 1265 270 275 280 285 290 295 300 305 310 315 320 325 330 335 340 345 350 355 360 365 370 375 380 385 390 395 400 405 410 415 420 425 430 435 440 445 450 455 460 195 89 197 70 199 50 201 30 203 09 204 88 206 67 208 46 210 25 212 03 213 81 215 58 217 36 219 13 220 90 222 66 224 42 226 18 227 94 229 69 231 44 233 19 234 93 236 67 238 41 240 15 241 88 243 61 245 34 247 06 248 78 250 50 252 22 253 93 255 64 257 34 259 05 260 75 262 45 264 14 265 83 267 52 Temperature C 465 470 475 480 485 490 495 500 505 510 515 520 525 530 535 540 545 550 555 560 565 570 575 580 585 590 595 600 605 610 615 620 625 630 635 640 645 650 Resistance of Element Ohms 269 21 270 89 272 57 274 25 275 93 277 60 279 27 280 93 282 59 284 25 285 91 287 57 289 22 290 87 292 52 294 16 295 80 297 43 299 07 300 70 302 33 303 95 305 58 307 20 308 82 310 43 312 04 313 65 315 26 316 86 318 46 320 05 321 65 323 24 324 83 326 41 327 99 329 57 Temperature C Resistance of Element Ohms 110 115 120 125 130 135 140 145 150 155 160 165 170 175 180 185 190 195 200 205 210 215 2
4. THAT THIS MODEL BE RETURNED TO THE FACTORY FOR RECALIBRATION Note Under normal conditions complete calibration should be performed every 6 months After repair of the unit or some other change in the electronics it is neces only to recalibrate those circuits affected by the change 5 2 2 Equipment Required The following is a list of test equipment necessary for calibration a b i Chart Recorder Harvard 2000 Series Oscilloscope general purpose with filter cut offs D C Source Digitec Model 3110 or equivalent D C Source 500V for over voltage checking A C Source Wavetek Model 142 or equivalent A C Source 260V Isolated DVM Keithley 172 or equivalent General Resistance RTD 100 Simulator Decade Resistance Box DB 62 or equivalent 5 2 3 Preliminary Procedure a Set Front Panel controls as follows DEG FULL SCALE OFF F C SWITCH c SENSITIVITY Detent xl Set internal controls as follows Remove shorting plug from E23 and E24 Make sure shorting plug is on E7 and E8 Set RTD Therm Switch to RTD Connect the Amplifier to a 2000 Series Recorder or appropriate power source d Use a 2 KQ resistor across the output when the preamplifier is not connected witl Harvard Recorder e Use a 100 Q precision resistor across the input See Figure 5 1 for a reference f Power ON Warm up approximately 10 minutes 5 2 4 Preliminary Adjustments and Checks Follow the steps of Table 5 1 in order after c
5. normal way as with RTDs SECTION V CALIBRATION AND MAINTENANCE 5 1 MAINTENANCE a General Maintenance on the preamplifier is limited to cleaning only CAUTION 1 Before attempting to clean preamplifier turn OFF power and remove from enclo 2 Avoid use of chemical cleaning agents which might damage plastic or printed surfaces Do not use chemicals which contain toluene Cellusolve acetone or similar solvents EXTERIOR Remove loose dust with a soft cloth or small paint brush dirt which remains can be removed with a soft cloth dampened in a mild detergent and water solution DO NO USE ABRASIVE CLEANERS INTERIOR Dust in the interior should be removed occasionally due to its electrical conductivity under high humidity conditions Blow off accumulated dust with dry low pressure lt Remove any dirt which remains with a soft paint brush or a soft cloth dampened in mild detergent and water solution A cotton tipped applicator is useful for cleaning narrow spaces and or printed circuit boards 5 2 CALIBRATION 5 2 1 General The Harvard Temperature Amplifier Model 13 4615 47 has been accurately calibre before shipment from the factory and should give long troublefree service Should recalibration be required it should be performed by qualified technical personnel o CAUTION CALIBRATION SHOULD NOT BE ATTEMPTED UNLESS SUITABLE SPECIFIEE TEST EQUIPMENT IS USED SINCE SPECIAL HIGH PRECISION EQUIPMENT IS REQUIRE ITIS RECOMMENDED
6. 1 1 INTRODUCTION The Harvard Model 13 4615 47 Temperature Amplifier Figure 1 1 is designed to give very accurate temperature readings in fractions of a degree over an extremely wide range temperature by using several different values of RTD s and Thermistor Probes This versatile amplifier is capable of handling four different basic RTD values of 100 200 500 and 10009 by simply installing a jumper in the appropriate position Contacts E 25 and E 26 are provided to extend the rang of RTD resistance values An internal switch is provided to adapt the amplifier to Thermistor operation A front panel switch is provided so that s specific temperature can be read in Farenheit as well as Celsius For ease of setup the attenuator switch is presented in Degrees Full Scale form 1000 Degrees to as little as 2 Degrees Full Scale The sensitivity control permits stepless adjustment of from 1 to 2 5 times the Full Scale reading The amplifier would not be complete without the Degrees Suppression Switch This switch allows you the extreme versatility that is promised You are able to suppress 999 Degrees of temperature either plus or minus The Harvard Temperature amplifier is compatible with Harvard 200 and 2000 Series Direct Writing Recorders It may be used independently or with other recording systems when installed in an optional portable or rack mounted case with a built in power supply 1 2 SPECIFICATIONS Measurement Range 240 to 1200 F
7. 20 225 230 235 240 245 250 255 260 265 270 275 280 285 290 Temperature vs Resistance Table Copper Probe 10 Q 0 C 209 214 218 223 228 233 238 243 248 253 259 264 269 275 280 286 292 297 303 309 315 321 328 334 340 347 353 360 366 373 380 387 394 401 408 416 423 32 00 C Ohm 50 7 9 40 8 32 30 8 74 20 9 16 10 9 58 0 10 00 10 10 42 20 10 84 30 11 26 40 11 68 50 12 10 60 12 53 70 12 95 80 13 37 90 13 79 100 14 21 110 14 63 120 15 06 130 15 48 140 15 90 150 16 32 160 16 73 Appendix Schematic Drawings This section contains complete schematic drawings for this Harvard product The schematics are arranged in numerical order by drawing number All documents included in this section are listed below in alphanumeric order by title along with t drawing numbers to help locate them The part number of any PC board assembly be obtained by replacing the initial 2 in the schematic number with an 8 Alphabetical List of Schematics Description of Assembly Schematic Drawing Number amp Revision I Preamplifier Assembly 13 4615 47 295377 A 1 Board Assembly 295269 S 2 Preamplifier Assy 13 4615 474029 CL 212200
8. 5 Pen should remain on right edge 6 Remove Probe Let it hang in air assuming 68 F 20 C Pen should swing 80 lin to the left 7 Change the F C switch to F and the Degrees F S switch to 100 With the Probe in water the deflection to the left should be 32 lines With the Probe hanging in air approximate deflection should be 68 lines Assuming 100 lines channel divide by 2 for 50 lines channel 4 GENERAL The Temperature preamplifier 13 4615 47 is an amplifier primarily designed to g temperature readings to the fraction of a degree celsius utilizing as a transducer a platinum type 385 RTD Resistance Temperature Device when wired to a 2000 Se Recorder or related equipment The preamplifier will also accept other RTD Probes as Platinum 392 copper or nickel or by internal switch except Thermistors such the YSI 400 4 2 THE RTD Platinum RTDs have highly stable characteristics and are outstandingly reproducible Their resistance is a function of temperature However the relationship of resistanc temperature is non linear and necessitates careful design or linearization circuitry An RTD in its simplest form could be as follows It would be necessary to read the ohmmeter value and then refer to a chart to perc the correct temperature The current flow through the RTD must be kept low to pr self heating Small deviations would be limited by the resolution of the meter We are capable of in this RTD Temperature A
9. DVM Zero Switch in the Zero position Output should read 0 0 volts 2 5 mV 5 3 8 Degree Centigrade Fahrenheit Conversion Set the 10 100 mV switch in the 10 mV position Adjust R Standard per the following Table Monitor the edge connector pin 2 Hi pin 5 Lo as in the following Table R Standard Temp F C Output Tol Q Degrees Switch Volts mV 39 65 150 C 1 50 5 39 65 238 F 2 38 10 84 21 40 F 40 10 84 21 40 C 40 5 100 00 0 C 0 00 5 100 00 32 F 32 10 138 50 22 F 2 012 10 138 50 100 C 1 00 5 329 57 650 C 6 50 13 329 25 1200 F 12 00 25 5 3 9 Output Noise 1 Set Full Scale switch to 2 5 6 Degrees F C to C Set R Standard at 100 00 Q Attach an oscilloscope frequency response limited to 100 Hz to the edge connec pin 2 Hi pin 5 Lo Keep preamplifier away from strong AC fields Noise as read on the scope must be less than 10 mV p p 5 3 10 Output Oscillating Check A 1 4 5 Switching Offset Control Set as in steps 1 2 3 of Output Noise above Attach a 2 KQ resistor and a 02 u fd capacitor across pins 5 and 2 of the edge connector The scope Bandwidth should be 10 MHz and the input set at AC Switch the Degrees Offset between 100 and 000 Observe the scope for evidence of oscillation Disregard switching transients Switching Resistance Box Place the 2K resistor and the 02 u fd capacitor across pins 5 and 2 of the edge connector Alternate
10. R 6 10 Volt Reference Sets 10 volt reference voltage R7 Therm Excitation Sets excitation voltage for thermistor R 8 Zero Thermistor Sets bridge zero for thermistor operation R9 Gain Sets gain of input stage for RTD operation R10 Zero RTD Sets zero for RTD operation Item Control Description R 11 Mid Range Used to adjust mid range equalization for RTD operation R 12 Hi End Used to adjust high end equalization for RTD opera R 13 F Offset Used to feed in the equivalent of 32 degrees durin the conversion of degrees C to degrees F R 14 U2 Offset Removes offset voltage from U2 R 15 U3 Offset Removes offset voltage from U3 R 16 U5 Gain Sets gain of output stage U5 R 17 U6 Offset Removes offset voltage from U6 R 18 10 volt reference Sets 10 000 volt reference voltage S2 RTD Therm Used to convert from RTD to Thermistor Probe operation S 3 10mV 100mV Used to select DPM output at 10mV Degrees or 100mV Degrees 3 4 PRELIMINARY OPERATION RTD 1 Set Deg F S to OFF 2 Sensitivity to X1 Detent 3 F C Switch to C 4 Degrees Suppression 000 5 Internal Controls a RTD Therm to RTD b Jumper across E7 E8 for 100 Q RTD 3 5 OPERATION RTD 1 Install preamplifier 2 Hook up test resistor 100 Q 1 or 1002 RTD as shown in Figure 3 3 If you use an RTD put it in ice water 3 Turn on recorder 4 Adjust pen position to the right edge of the chart 5 Turn Deg Full Scale to 100 Pen should remain on the right edge 6 Change
11. Voltage Tol Copper 10 Q RTD Value Q Hi Lo Adjust Reading mV See Table 2 2 Copper 10 10 1 2 RI 50 mV 1 4 3 R9 1 870 V 5 5 3 R10 0 V 2 Simulate 93 33 Deg C 13 93 5 3 R9 746 V 2 Simulate 0 Deg C 10 5 3 R10 0 V 2 Repeat last two steps until no further adjustment is necessary Rtd Simulator Voltage Tol Copper 100 O RTD Value Q Hi Lo Adjust Reading mV See Table 2 2 Copper 100 100 1 2 RI 50 mV 1 4 3 R9 1 870 V 5 5 3 R10 0 V 2 Simulate 93 33 Deg C 139 3 5 3 R9 746 V 2 Simulate 0 Deg C 100 5 3 R10 0 V 2 Repeat last two steps until no further adjustment is necessary Rtd Simulator Voltage Tol Copper 100 O RTD Value Q Hi Lo Adjust Reading mV See Table 2 2 Nickel 120 NOTE Do not touch R4 if it was tampered with see speci note Turn R12 to full CW position Amplifier OFF Ohmmeter 6 5 R11 Adjust to 22 kQ 1K SPECIAL NOTE To adjust R4 remove jumper E27 28 120 1 2 R4 240 mV 1 Re install jumper at E27 28 Simulate 0 Deg C 120 5 3 R10 0 V 2 Simulate 93 33 Deg C 200 14 5 3 R9 8 V 2 Simulate 0 Deg C 280 82 5 3 R10 644 V 5 Repeat steps in order until no further adjustment is necessary See Appendix A for Temperature Resistance Tables covering Platinum Nickel and Copper RTD probes Table 2 1 Jumper Placement RTD Probes Platinum Type 385 Probe Resistance Jumper 100 Q E7 E8 200 Q E5 E6 500 Q E3 E4 1000 Q El E2 TABLE 3 2 RESISTOR TABLE RTD PLUG IN RESISTORS Resistor Pl
12. ace R 42 E9 E10 R 46 E11 E12 R 50 E13 4 E14 R 103 E25 4 E26 Short E27 4 E28 Short E23 4 E24 E7 E8 ES E6 E3 E4 El E2 3 1 GENERAL This section illustrates and describes the controls of the Temperature Platinum 4 5 KQ 98 KQ 225 KQ Jumper See Table 2 1 Nickel 120 6 7 KQ 118 KQ Jumper Jumper Jumper for jumper placement Section III OPERATION Copper 10 965 Q 104 KQ 665 Q 13 4615 47 and provides complete operating instructions 3 2 FRONT PANEL CONTROLS Item numbers listed below refer to circled numbers in Figure 3 1 Item Control 1 Attenuator 2 F C 3 Degrees Offset 4 Sensitivity 5 DPM Zero 3 3 INTERNAL CONTROLS Description Selects full scale sensitivity Copper 100 965 Q 104 KQ 13 KQ Amplifier Mo Toggle switch selects either F or C Selects polarity of offset and steps 0 through 999 degrees in one degree steps Thumbwheel switch Single turn potentiometer with locking knob Multiplies full scale sensitivity by a minimum of 2 Spring return toggle switch Zeroes out the Digital Panel Meter Item numbers listed below refer to numbers in Figure 3 2 Item Control Description R 1 RTD 1000 Sets current for 1000 Q RTD probes R2 RTD 500 Sets current for 500 O RTD probes R3 RTD 200 Sets current for 200 O RTD probes R 4 RTD 100 Sets current for 100 O RTD probes R5 4 Volt Reference Sets 4 000 volts reference across TP 16 and TP 17
13. basic ranges of RTD can be accommodated by simply switching in the p jumper Small variations can be adjusted 5 by the four single turn pots 4 4 DEGREE CENTIGRADE TO DEGREE FAHRENHEIT CONVERTER FIGURE 4 3 At the flip of a switch you can convert from Centigrade to Fahrenheit An operation amplifier converts the formula Deg Far 9 5 Deg Cent 32 for this accomplishmer Thirty two 32 Degrees is injected in the circuit at R 13 at the rate of 8 mV degre The output therefore is equal to 32 x 8 256 mV 32 F The output of the C to F Converter stage goes two ways One is to a non inverting that has a gain o 1 25 10mV or 12 5 100mV The output of this stage is used drive external panel meters or other devices at 10 or 100 mV The second path is used to supply 8 mV degree to the summing point of the suppression amplifier 4 5 SUPPRESSION AMPLIFIER FIGURE 4 4 Twelve binary weighted resistors coupled with three decade Thumbwheel switches introduce a plus or minus offset in one degree steps from one to 999 The output of stage is at 8 mV degree The output of this stage goes to the sensitivity control th the attenuator which has 2 to 1000 Full Scale settings plus OFF 4 6 OUTPUT STAGE FIGURE 4 5 The attenuator drives an Intersil IC L7650CPD Op Amp This device was chosen for excellent specifications as to offset voltage and temperature drift Its output swing somewhat limited because of its 8 volt suppl
14. essories Extender Card and Cable Assembly R1 288308 45000 R1 288308 10002 R1 288308 22502 887291 Connector Adapter Adapt Phone Plug for YSI Thermistors 11 5407 54 Recalibrating Kit Assembly see Paragraph 2 7 3 696167 SECTION 11 INSTALLATION 2 GENERAL This section describes the checks and inspections that should be made upon receiving the Harvard Temperature Amplifier Model 13 4615 47 with a Temperature Amplifier Model 13 4615 47 with a 2000 series unit It covers installation procedures signal input connections and outline dimensions 2 2 INITIAL INSPECTION Prior to attempting any electrical connections or operation visually examine the unit for broken or loose knobs dented or nicked panels and broken or chipped rear connectors 2 3 INSTALLATION Preamplifier Model 13 4615 47 may be mounted in Harvard 2000 Recorder frames Harvard portable case or rack mounted separately in a Harvard rack adapter kit 1 Insertion To install the preamplifier into its appropriate slot a Slide the preamplifier into the enclosure until the rear output card edge connector is engaged See Figure 2 1 REAR VIEW b Tighten the rear retaining screw until the preamplifier front panel is flush with the edge of the enclosure DO NOT OVERTIGHTEN This locks the preamplifier into the enclosure c Connect the 7 pin plastic input signal connector and secure it by turning the threaded plastic locking ring clockwise 2 Re
15. input resistor to 138 5 Q 1 100 Pen will move to left chart edge Remove the probe from the ice water and let it hang in the room assuming 68 F 20 room temperature The pen should deflect 20 divisions to the left Change the F C Switch to F Using the resistor 100 Q at the input 32 lines deflection to the left 32 F With 114 67 O at input 100 lines deflection to the left 100 F Using a 100 Q RTD Probe in ice water 32 lines deflection to the left 32 F With RTD Probe hanging in air 68 lines deflection to the left 68 F Assuming 100 lines channel divide by 2 for 50 lines channel 3 6 ZERO SUPPRESSION After completion of paragraph 3 5 you can test the Zero Suppression by dialing in a negative temperature equivalent to the temperature that is then being recorded Example If you are recording 68 you would dial 68 The pen would then deflect t or the right edge The recorder would then display 68 attenuator setting 68 3 7 PRELIMINARY OPERATION THERMISTOR 1 2s C Set Deg F S to OFF Sensitivity to X1 Detent F CtoC Degrees Suppression 000 Internal Controls RTD Therm Switch to Therm Remove R46 between E11 E12 Remove R42 between E9 E10 3 8 OPERATION THERMISTOR l Install preamplifier 2 Hook up Thermistor Probe and put it in ice water as in Figure 3 4 3 Turn on recorder 4 Adjust the pen position to the right chart edge 5 Turn Degrees F S to 2
16. l Scale Positions per Table R Standard ohms 100 00 100 78 101 95 103 90 109 73 119 40 138 50 194 08 280 93 329 57 0 2 5 10 25 50 100 250 500 5 3 6 Variable Sensitivity Linearity Set the Full Scale Switch to 100 Set the R Standard to 138 50 Q Output should be 5 volts 40 mV 64V 4E 13 2 72V 4E 14 8 80 mV E 56 800 mV E 2 08 72V E 14 8 n 5 Lo pin 2 Hi Output Tolerance Full Scale Volts Volts 2 0 1 2 5 1 5 5 a 10 5 25 25 5 1 50 5 05 100 5 04 250 5 02 500 5 02 1000 3 25 02 Turn the variable sensitivity CCW Output drops to below 2V Adjust variable sensitivity control so that the output is 2V 1 mV Change the R Standard to 194 08 Q Output now reads 5 volts 20 mV Adjust variable sensitivity for an output of 5 volts 1 mV R Standard Q 194 08 175 84 Output Volts 5 00 4 00 Tol mV 1 15 157 32 3 00 15 138 50 2 00 20 119 40 1 00 20 120 00 0 25 Turn the Full Scale Switch to OFF Turn variable sensitivity control CW to detent position 5 3 7 10 mV 100 mV Degree Check Full Scale switch to OFF Adjust R Standard to 138 50 Q Connect DVM to card edge connector pin 5 Lo pin J Hi With the 10 mV 100 mV switch in the 10 mV position output should read 1V 4 mV With the 10 mV 100 mV switch in the 100 mV position output should read 10 50 mV Hold the
17. moval a Disconnect the input connections with a counterclockwise turn to the connector and pull b Loosen the rear retaining screw The preamplifier will move forward about 1 8 of an inch c Carefully slide the entire preamplifier out of the Harvard 2000 enclosure 2 4 INPUT CONNECTIONS Figure 2 2 shows the pin connections located at the rear of the Temperature Amplifier For the convenience of the user a mating guarded multi pin connector Harvard Model 11 5407 50 is supplied For YSI Thermistor Probes use the Harvard Model 11 5407 54 connector 2 6 PRELIMINARY SET UP PLATINUM a Set switch S 2 see Figure 3 2 to RTD mode Make sure R 42 and R 46 see Figure 2 6 are inserted into E9 E10 and E11 E12 respectively A jumper must be installed into E7 E8 for 1000 RTD operation For other probe resistances see Table 2 1 Jumper for E23 E24 must be installed b The probe should be hooked to the preamplifier as described in paragraph 2 4 2 7 TYPICAL WIRING DIAGRAMS The following diagrams typify the ease of wiring the Probes to the preamplifier The pin numbers correspond to circled pin connections identified on Figure 2 2 2 7 1 RTD Probes After wiring per Figure 2 4 use the preliminary set up procedure given in paragraph 2 6 a These instructions and Table 2 2 should answer questions on the hookup and preliminary operation in the RTD mode 2 7 2 Thermistor Probes The amplifier is set up properly when S2 i
18. mplifier simplified reading of tempe and extended resolution to 2 degrees F or C Full Scale as seen by using our chart recorder as an indicating device This high resolution can be obtained up to 998 degrees plus or minus by using the Degrees OFF SET switch It can handle temperatures from 150 to 650 Centigrade 238 to 1200 Fahrenheit See Figure 4 1 Block Diagram on Page 4 2 The RTD is connected in a 4 wire configuration In this way the length of the connec wires do not effect the accuracy and the voltage developed across the RTD by the controlled current limiter is fed directly into a high impedance instrument amplifie 4 3 BASIC INPUT CIRCUITRY FIGURE 4 2 The key feature of this circuitry is the Lin A and Lin B feedback components Lin the main linearization path Lin B works only at the extremely high range when th associated diode barely comes into conduction At high temperatures Lin A and perhaps Lin B cause an increase in negative current that goes to the summing input the top amplifier This causes an increase in the output of the top amplifier which causes a corresponding increase in the current through the RTD resulting in Lineari at the output Since the gain is less than 1 and the feedback positive no oscillation occurs There is now at TP 5 an output of 8mV degree Celsius that represents the temperature of the RTD linearized to better than 5 degrees throughout the desired range Four
19. ompleting the following preliminary s up Step Description Test Points Output Resistan Hi Lo Volts Tol Adj 1 123 0 0 10mV None 2 143 10 0 ImV R 18 153 10 0 1mV R 6 3 1617 4 01 mV R 5 4 1 2 200 05mV R 4 Remove jumper E7 E8 install at 1 2 100 ImV R 3 Remove jumper E5 E6 install at 1 2 Remove jumper E3 E4 install at Remove jumper El E2 install at 5 4 3 6 7 5 2 5 Main RTD Calibration Step Description Test Points Output Resiste Hi Lo VoltsTol Adj 5 3 INSPECTION CHECKS 5 3 1 Hi Pot Make sure R 42 and R 46 are in place RTD jumper at E7 E8 RTD Therm Switch to RTD Jumper at E23 E24 in place Power on 5 minute warm up Input 260 VRMS 60 Hz through isolation transformer to pins 1 and 2 for 30 secc Remove Input 500 VDC between pin 5 and case for 30 seconds A current flow of over 10 mA on either set up indicates a balance WARNING HI VOLTAGE CAN KILL 5 3 2 Common Mode Rejection 1 Use Figure 3 for proper set up Input 100 Q Full Scale switch to 2 F C switch to C Thumbwheel to 000 Sensitivity full CW Short out 350 Q resistor going to input pin 1 Attach oscilloscope 2 hi 5 lo Scope Cut off 100 Hz to Output Card Edge Input 30 V p p 60 Hz Frame Lo 5 Hi Oscilloscope should read lt 90 mV p p Short out 350 Q resistor going to input pin 2 and open switch to pin 1 Output reading should be the same as in step 4 Remove Generator and oscilloscope Substitute DVM in
20. place of Scope Attach a 400 VDC supply in place of the oscillator Frame pin 5 Use a 10 mA fuse for protection Disregard initial voltage shift when first turned on New reading should not vary more than 125 mV from initial reading Repeat step 6 shorting resistor in leg with pin 2 and opening the one with pinl Remove voltage Short both 350 Q resistors 5 3 3 RTD Zero Set RTD box to 100 000 Q 0 C Full Scale Switch to OFF Output 0 0V 10 mV Full Scale Switch to 100 Output O OV 15 mV Full Scale Switch to 2 Output O OV 1V 5 3 4 Degrees Suppression Linearity and Accuracy Monitor with DVM TP 3 Lo TP 9 Hi Set thumbwheel switch to 000 Use Figure 5 1 for input Adjust R standard for least error Follow the Table Thumbwheel DVM Reading Tolerance mV Deg Offset E Error Adjust 000 Error Reading 001 8mV E 416 002 16mV E 432 003 24mV E 448 004 32 mV E 464 005 40 mV E 480 006 48 mV E 496 007 56 mV E 512 008 64 mV E 528 009 72 mV E 544 010 80 mV E 560 020 160 mV E 720 030 240 mV E 880 040 320 mV E 1 040 050 400 mV E 1 020 060 480 mV E 1 36 070 560 mV E 1 52 080 640 mV E 1 68 090 720 mV E 1 84 100 800 mV E 2 08 200 16V E 3 6 300 24V E 5 2 400 32V 4E 6 8 500 40V E 8 4 600 48V E 10 0 700 5 6V E 11 6 800 900 010 100 900 5 3 5 Full Scale Accuracy Connect DVM to edge connector pi Check output in all Ful
21. rmistor Test 1 Set up input as in Figure 5 2 2 Put RTD Therm switch in Therm mode 3 Unplug R 42 and R 46 4 Connector DVM Lo to pin 5 Hi to pin 2 on edge connector 5 Sensitivity at detent position 6 Offset to 000 7 Degrees F C in C position 8 Test per the following Table Therm Sw Resistor F S Sw Reading Volts Centigrade Ohms 0 7355 2 0 4 6011 5 4 10 4483 10 5 20 2814 25 4 30 1815 25 6 38 1301 50 3 8 42 1108 50 4 2 Tol 2 2 V i9 125 100 mV 100 50 100 9 This completes inspection 10 Restore R 42 and R 46 to their proper positions 11 Rut RTD Therm Switch in RTD mode Appendix A Temperature Vs Resistance Table Platinum 385 100 Q 0 C C Ohm 100 60 20 95 62 23 90 64 25 85 66 27 80 68 28 75 70 29 70 72 29 65 74 29 60 76 28 55 78 27 50 80 25 45 82 23 40 84 21 35 86 19 30 88 17 25 90 15 20 92 13 15 94 10 10 96 07 5 98 04 0 100 00 5 101 95 10 103 90 15 105 85 20 107 79 25 109 73 30 111 67 35 113 61 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235 240 245 250 117 47 119 40 121 32 123 24 125 16 127 07 128 98 130 89 132 80 134 70 136 60 138 50 140 39 142 28 144 17 146 06 147 94 149 82 151 70 153 57 155 45 157 32 159 19
22. s in the Thermistor Mode and R 42 and R 46 have been removed from their operating position and stored see Figure 2 6 This amplifier has been calibrated at the factory for use with YSI 400 Thermistors so no adjustment should be necessary for proper operation The YSI 400 Thermistor Probes Harvard part numbers 369500 18010 thru 18026 are to be used with our connector Adapter 11 5407 47 For a fast test of your probe and amplifier operation you can try the following Set up the amplifier as in the preceding paragraph Degrees Suppression to 000 e F C Switch C Place probe tip in Ice Water distilled 0 C e Oscillograph to Zero Center with Degrees Full Scale at 0 Degrees Full Scale to 2 Adjust R 8 if necessary to center of chart For any further adjustment refer to the section on Calibration 2 7 3 Recalibration Kit Assembly In order to operate this amplifier with other than Platinum Probes some other resistors are necessary as described in Table 2 2 By ordering part number 696167 Kit Assembly you will receive the following resistors and two jumper leads all packaged together Symbol Part Description 696167 Kit Assembly R 42 R1 288308 965RO Resistor 9650 R 42 50 281851 67000 Resistor 6 7 KQ R 46 50 281851 10402 Resistor 104 KQ R 46 50 281851 11802 Resistor 118 KQ R 103 50 281851 13001 Resistor 13 KQ R 103 50 281851 665R0 Resistor 6652 267235 Jumper 2 in kit 2 7 4 Recalibration Rtd Simulator
23. the R Standard between 100 00 and 200 00 Q There should be no evidence of oscillation Use both the 10 and 100 mV Degree positions for this test Leave the switch in the 10 mV position 5 3 11 Frequency Response 1 Attach the amplifier as in Figure 5 4 10 11 12 13 14 Set Full Scale Switch to 10 Set Degrees F C to C Use an oscilloscope with a bandwidth of 1 KHz Set Scope on AC Set the AC Generator to 1 Hz Sine Wave Adjust the amplitude of the generator to give a 5 Volt p p response on the oscilloscope Raise the generator frequency until the amplitude on the scope drops to 3 5 V p Generator output amplitude must be held constant This frequency must fall between 8 and 12 Hz Change generator frequency to 100 Hz Shunt 250K resistor with 50K Adjust generator for a 5V p p readout on the scope Readjust the generator frequency to 200 Hz Generator output amplitude must held constant The scope reading should have dropped to 50 mV p p Remove all connections 5 3 12 RTD Test 100 1000 Q 1 2s Set the FS switch to 100 Degrees F C switch to C Offset to 000 Install the 100 00 Q resistor at the input Use Figure 5 1 for reference Output should read 0 00 V 15 mV Check Table for proper RTD jumper position to match the input resistance T RTD Jumper Input Resistance Ohms E7 E8 100 00 E5 E6 200 00 E3 E4 500 00 E1 E2 1000 00 Re install jumper at E7 E8 5 3 13 The
24. y Latch up was a major problem If the input voltage is allowed to increase over the supply voltage on either of its inputs latch up would occur To take care of latch u 20 KQ resistor was installed in the input line This limits the current to less than 1 thus preventing the latch up We need a gain of 312 5 in this output segment Because the Intersil Amp has limit output we lowered its gain to 156 75 At the same time adding a 741 IC to be used output amplifier with a gain of approximately 2 R 16 was provided so that the exa gain can be set NOTE Most internal manipulations are handled at 8mV degree This level allows fo linear operation up to 1200 F which is 8 mV x 1200 or 9 6 Volts This is well witl the range of op amps using 15 volt supplies The RTD Amplifier has a high frequency response that is down 3 dB at 10 Hz 20 Additional filtering to lower the upper limit even more can be had by plug in capac not supplied 4 7 THERMISTOR OPERATION An internal switch RTD Therm is provided to convert from RTD to Thermistor oper using YSI Type 400 Thermistor Probes For this mode the RTD Therm Switch sets uj bridge at the input R 42 input stage gain and R 46 input stage zero are unplugg The Bridge Circuit is as follows See Figure 4 6 Resistor R8 is used to adjust the low end of the desired range and the voltage feedii the bridge is adjusted so that TP 5 output is 8 mV C From this point the output is handled in the
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