SPECTRO Inc. M90301 Operation User's Manual

Operation & User Manual
Source Frequency
Test Meter
Part Number M90301
Operation & User Manual
Source Frequency
Test Meter
Part Number M90301
© 2008-2012 Spectro, Incorporated. All rights reserved.
The information and descriptions in this document are the sole property of Spectro Incorporated and may not be copied, reproduced, disseminated, or distributed without explicit written permission from Spectro Incorporated. The statements, confi gurations, technical data, and recommendations in this document are believed to be accurate and reliable at the time of this publication, but Spectro Incorporated assumes no responsibility or liability for any errors or inaccuracies that may appear in this document. Spectro Incorporated is not responsible for any infringement of patents or other rights of third parties that may result from the use of this document. The content of this document is furnished for informational purposes only, is subject to change without notice, and does not represent a commitment or guaranty by Spectro Incorporated. Spectro Incorporated makes no warranty, express or implied, with respect to the content of this document. Spectro Incorporated shall not be liable for any loss or damage, including consequential or special damages, resulting from any use of this information, even if loss or damage is caused by Spectro Incorporated as a result of negligence or any other fault.
FluidScan is a registered trademark and SpectroInc, Spectroil, SpectroVisc, SpectroTrack, SpectroLNF, SpectroFTIR, and SpectroFDM are trademarks of Spectro, Incorporated. All other trademarks are the property of their respective holders.
Spectro Incorporated (“Spectro Inc.”) warrants to the original purchaser only, that all Spectro Inc. bench top instruments will be free from defects in material or workmanship for a period of twelve (12) months from date of installation or fi fteen (15) months from the date of shipment, whichever occurs fi rst. SPECTRO INC.’S SOLE OBLIGATION AND YOUR EXCLUSIVE REMEDY under this Limited Warranty and, to the extent permitted by law, any warranty or condition implied by law, shall be the repair or replacement of parts, without charge, which are defective in material or workmanship and which have not been misused, carelessly handled, abnormal conditions or operation, accidents or acts of God, or misrepaired by persons other than Spectro Inc. or Authorized Service Provider. To make a claim under this Limited Warranty, you must contact the Spectro Inc. Factory Service Center or Authorized Service Provider. The determination of whether any product has been subject to misuse or abuse will be made solely by Spectro Inc. If a hardware defect arises and a valid claim is received within the limited warranty period, at its option and to the extent permitted by law, Spectro Inc. will either (1) repair the hardware defect at no charge, using new parts or refurbished parts that are equivalent to new in performance and reliability, or (2) exchange the product with a product that is new or refurbished that is equivalent to new in performance and reliability and is at least functionally equivalent to the original product. Spectro Inc. may request that you replace defective parts with user-installable new or refurbished parts that Spectro Inc. provides in fulfi llment of its warranty obligation. A replacement product or part, including a user-installable part that has been installed in accordance with instructions provided by Spectro Inc., assumes the remaining warranty of the original product. For Authorized Service Provider, please contact Spectro Inc. Technical Support, +1-978-431-1130, or support@ spectroinc.com.
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Register Your Product.
Register your product online at http://www.spectroinc.com/register.htm.
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Product Safety
WARNING: High voltages are present during the operation of the Spectroil M! Observe all safety precautions! Turn OFF the main power switch and unplug the Spectroil M before performing any work.
Software CAUTION: Do not attempt to add any software or alter the original factory-installed software without checking fi rst with the Spectro Inc. Service Department.
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Product Safety Operation & User Manual
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Source Frequency Test Meter || vii
Contents
1.0 INTRODUCTION ......................................................................................................... 1
2.0 DESCRIPTION & SPECIFICATIONS .......................................................................... 3
3.0 MAINTENANCE & ADJUSTMENT ............................................................................ 5
3.1 Display Contrast Adjustment ........................................................................................... 5
3.2 Battery Replacement ........................................................................................................5
3.3 Calibration ....................................................................................................................... 6
4.0 PROCEDURE TO CHECK THE EXCITATION SOURCE FREQUENCY .................. 7
4.1. Auxiliary Gap Optical Fiber View ..................................................................................... 7
4.2 Auxiliary Gap Direct View ............................................................................................... 9
5.0 DETAILED DESCRIPTION OF EXCITATION SOURCE FREQUENCY ................. 13
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List of Effective Pages
 is manual consists of 18 pages plus a cover.
Summary of SFTM Manual Versions
Change
Ver-
Date Description
First Issue 1.0 30 June 1995 CID versions of the Spectroil M and Spectroil Jr+ 1 1.1 29 July 2008 Updated manual for current versions of the Spectroil M
that have SFTM docking ports.
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Section 1.0
Introduction
Source Frequency Test Meter || 1
1.0 INTRODUCTION
 is manual provides a description of the Source Frequency Test Meter (SFTM) and step-by-step procedure to measure and adjust the excitation source frequency of the Spectroil M family of Oil Analysis Spectrometers. Proper care and opera­tion of the Source Frequency Test Meter (SFTM), part number M90300 and information on the maintenance and adjustments to the SFTM are also provided.
 e Source Frequency Test Meter (SFTM) Figure 1-1, is a hand-held electronic measurement device used to check the frequency of oscillatory arc exci­tation sources.  e SFTM is easy to operate, it is battery operated, requires no calibration, and can be used in place of an oscilloscope. It is shipped in its own carrying case and includes the four AA batteries required for operation.
 e excitation sources in all versions of the Spectroil M are an oscillatory arc discharge.  ey have been designed to achieve excitation charac­teristics that produce a spectral signature to match the United States Department of Defense Joint Oil Analysis Program (JOAP) date base.  e per-
Figure 1-1, Source Frequency Test Meter
(SFTM) in its carrying case
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formance of the Spectroil M is directly dependent on the output characteristics and frequency of the oscillatory arc source.
It is absolutely necessary to check the excitation source frequency prior to performing the JOAP monthly correlation samples.  e source frequen­cy also has to be checked each time the instrument is deployed to a country where the line frequency is other than 60 Hertz, and/or to verify that no damage was incurred during transport.
Description and user maintenance of the SFTM is provided in Sections 2 and 3 of this manual. Step-by-step procedures for setting the excitation source frequencies of the Spectroil M are provided in Section 4.0 and a detailed description of the excitation source frequency and the need to verify it is explained in Section 5.
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Section 2.0
Description &
Specifi cations
2.0 DESCRIPTION & SPECIFICATIONS
 e Source Frequency Test Meter is a hand-held device used to check and to verify the excitation source frequency of the Spectroil M family of oil analysis spectrometers. It includes its’ own carrying case the four AA batteries required for operation. A special adapter is pre-installed for connection to the SFTM port on Spectroil M spectrometers.
 e SFTM control buttons used in measuring excitation source frequency, are noted in Figure 2-1.  e step-by-step procedure for checking the excitation source frequency of a Spectroil M is de­scribed in Section 4.0 of this manual.
Input Coupler / Aiming Light
Momentary Power Switch
MEMORY Switch
CONTRAST Control
Figure 2-1, Source Frequency Test Meter
(SFTM)
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SFTM SPECIFICATIONS
Item Description
Display: 5 digits, 10 mm (0,4”) Liquid Crystal (LCD) Measuring Range: 5 to 99,999 counts Resolution: 0.1 count ( < 1,000 discharge/min.
1 discharge/min. (> 1,000 counts)
Accuracy: +/- (0.05% + 1 count) Time Base: Quartz Crystal, 4.194 Mhz Operating Temperature: 0-50°C (32 - 122°F) Memory: Last/Maximum/Minimum values Battery: Four 1.5 volt AA batteries Power Consumption: Approximately 153 ma Size: 165 x 61 x 39 mm (6.5 x 2.4 x 1.5 inch) Weight: 235 g (0.52 LB) including batteries
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Section 3
Maintenance &
Adjustment
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3.0 MAINTENANCE & ADJUSTMENT
3.1 Display Contrast Adjustment
 e contrast of the LCD display may vary due to battery voltage drop or a change of the viewing angle.  e contrast is variable with the “CON­TRAST” adjustment knob on the control panel of the SFTM. It should be set for viewer prefer­ence.
3.2 Battery Replacement
 e LCD display will have a “LO” indication to warn the user that the batteries are low and should be replaced.  e warning appears when the bat­teries have discharged from the original 6.0 volts to approximately 4.5 volts. When the “LO” in­dication  rst appears, the SFTM can still be used for several hours, however, it is good practice to replace the batteries at the  rst opportunity.
 e battery compartment, Figure 3-1 is on the back of the SFTM.  e battery compartment
Table 3-1, SFTM battery compartment with
cover removed
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cover can be removed by momentarily depressing the latch with your  nger. Replace the old batter­ies with four (4) fresh AA batteries.  e correct polarity and location of the batteries is shown in each socket. All four batteries should be replaced at the same time. Replace the cover by lining up the bottom slots and closing until a “click” is heard to signify that it is latched.
3.3 Calibration
 e Source Frequency Test Meter does not require calibration with normal use.  e discharge rate is counted and controlled by a 4.194 MHz quartz crystal similar to a quartz watch.
Under normal circumstances, the SFTM does not require calibration. To verify calibration, point the SFTM toward a  uorescent light  xture and press and hold the Momentary Power Switch for at least 10 seconds. For power sources with 60 Hertz, the meter should read 7,200 +/- 100 and for 50 Hertz power sources, 6,000 +/- 100. If the SFTM measurement exceeds the tolerances speci­ ed, utilize the oscilloscope method.
Contact Spectro Inc. if you suspect that your SFTM has been abused and/or its operation is suspect.
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Section 4
Procedure
to Check the
Excitation
Source
Frequency
4.0 PROCEDURE TO CHECK THE EXCITATION SOURCE FREQUENCY
 ere are two methods to check the excitation source frequency using the Source Frequency Test Meter.  e  rst method employs an optical  ber that views the arc discharges as they occur across the auxiliary gap.  e second method measures the source frequency by directly viewing the arc discharges that occur across the auxiliary gap. Both methods work equally well, but the advan­tage of the  rst method is that it is faster and also does not expose the operator to areas with live voltage. Follow the steps listed below to check the excitation source frequency using the SFTM.
4.1. Auxiliary Gap Optical Fiber View
To check the excitation source frequency by mea­suring the discharges per minute across the auxil­iary gap using the SFTM, follow the steps listed below.
NOTE:  is procedure should be performed by the operator once per month prior to JOAP monthly correlations, whenever the instrument is moved, or every 2,000 burns.
1. Remove the SFTM from the protective con­tainer. If this is the  rst time this test meter is to be used, four AA size batteries will have to be installed before it can be operated.  ese batteries are provided with the test meter.
2. Hold the SFTM in the right hand and with your thumb, press and hold the momentary switch located on the upper right side of the SFTM.  is will turn the test meter ON and along the right side of the digital display a “0” (zero) should appear. If the image of the “0” is not clear, or if many characters simultaneously appear on the display, the CONTRAST control should be adjusted.
NOTE: Under normal circumstances, the SFTM does not require calibration. To verify calibration,
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point the SFTM toward a  uorescent light  xture and press and hold the Momentary Power Switch for at least 10 seconds. For power sources with 60 Hertz, the meter should read 7,200 +/- 100 and for 50 Hertz power sources, 6,000 +/- 100. If the SFTM measurement exceeds the tolerances speci ed, utilize the oscilloscope method.
3. Remove the threaded protective dust cover from the SFTM PORT and insert the dock­ing coupler of the SFTM into the SFTM PORT until it stops.  e SFTM coupler has a guide so that it can only be inserted at a convenient viewing angle. Refer to Figure 4-1.
4. Set the MODE switch on the control panel to OPERATE.
NOTE: Make four warm-up burns before proceed­ing.
5. Prepare the sample excitation stand for a routine analysis with a new disc and rod electrode and set the analytical gap in ac­cordance with the Spectroil M Operator’s Manual. Place a sample holder on the sample table and  ll it with base oil (0 ppm) standard oil. Raise the sample holder into the normal position. Close the sample stand door.
6. Press the START switch located on the front control panel.  e burn cycle will begin and the high voltage across the auxiliary gap will
appear as a concentrated stream of light. In actuality, this steam of light consists of ap­proximately 700 high voltage discharges per second and the function of the SFTM is to detect and quantify these arc discharges.
7. Press and hold the momentary power switch on the SFTM after the preburn period has completed (after approximately 6 sec­onds). If the SFTM is properly positioned to receive the light emitted across the aux­iliary gap, a small red light emitting diode (LED) located above the digital display of the SFTM will begin to  ash at a consistent rate. Hold the position of the SFTM steady and continue to hold the momentary power switch and monitor the consistency of the red LED to ensure that the signal is strong and consistent. Once the burn cycle is com­plete (30 seconds), release the momentary power ON switch of the SFTM and remove the SFTM from the port for a more conve­nient observation of the measurement.
NOTE: It is normal to observe  uctuations of approximately +/- 1000 discharges per minute (DPM) during the measurement cycle.
NOTE: If the red LED does not appear or  ashed at an erratic rate, the SFTM is not in position to permit the light from the auxiliary gap to enter the test meter. Repeat the procedure until a steady  ash­ing red light is obtained.
8. When the burn is complete, press and hold the MEMORY switch located on front of the SFTM one time. A number will appear momentarily, then the letters “LA” (last) will appear.  is number should be ap­proximately 54,000 and represents the last measurement the SFTM made before the power switch was released.  is reading is not signi cant for this procedure. Release the MEMORY switch to end the reading.
Table 4-1, SFTM inserted in SFTM port and
ready for use
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9. Press and hold the MEMORY switch a second time and a new number will ap­pear.  is is the number that will be used to
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determine the excitation source frequency.  is number must be 54,000 +/- 2000. If the MEMORY switch is held, the letters “UP” will appear, which designates that this was the highest reading taken during the burn. If the source frequency is within this range, then proceed to step 12 of this procedure. If not, SFTM port  ber may be defective. Check frequency with the Direct View Method, Section 4.2.
10. Upon completion of the source frequency check, replace the dust cover on the SFTM PORT to prevent any accumulation of debris.
11. Return the SFTM to its protective storage container.
12.  is procedure is now complete.
Top Trim Panel
Circuit Breaker CB1
Table 4-2, Location of CB1 and top trim panel
Excitation
Source
Access Panel
4.2 Auxiliary Gap Direct View
To check the excitation source frequency by mea­suring the discharges per minute across the auxil­iary gap using the SFTM, follow the steps listed below.
WARNING:  is procedure should only be per­formed by a qualifi ed technician.
1. Remove power from the Spectroil M by placing the main power circuit breaker CB1 to the OFF or down position, Figure 4-2.
2. Remove the four Phillips head mount­ing screws positioned in the corners of the Spectroil M top trim panel, Figure 4-2. Be sure not to lose the dress washers for these panel screws; they are not captive to the screws. Remove the top trim panel.
3. To remove the top excitation source access panel (the smaller of the two panels) Figure 4-3, turn the six 1/4 turn pawl fasteners screws counterclockwise until the maximum travel of the screw is achieved, approximately 10 rotations.
Table 4-3, Excitation source access panel
CAUTION: Do not overdrive the counterclock­wise travel of these screws, stop when light resis­tance is encountered. Once all fasteners have been loosened, remove the top access panel.
NOTE:  is panel has a safety interlock switch to protect unauthorized personnel from removing this panel with power applied. Only trained operators and electronic maintenance personnel are autho­rized to enter this compartment. To perform service in the excitation source compartment, the operator/ technician must bypass this safety interlock switch.
4. To bypass the interlock switch, Figure 4-4, grasp the plunger and pull in an upward direction until the plunger moves approxi­mately 1/4 inch.  is will bypass the inter-
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Auxiliary
Gap
Safety
Interlock
Switch
Table 4-4, Location of safety interlock and auxiliary gap
lock switch function and permit power to be applied to the instrument. If either of two safety interlock switches are not properly positioned or bypassed, circuit breaker CB1 will fail to latch in the ON position.
5. Place the circuit breaker CB1 in the up or ON position.  is will apply power to the instrument and after the computer has loaded the software and selected the proper line voltage and frequency settings for the current location, a burn can be made.
NOTE: Make four warm-up burns before proceed­ing..
6. Prepare the sample excitation stand for a routine analysis with a new disc and rod electrode and set the analytical gap in ac­cordance with the Spectroil M Operator’s Manual. Pour a new sample of base (0 ppm) standard and place this sample in position for analysis. Close the sample stand door.
7. Set the MODE switch on the control panel to OPERATE.
8. Remove the SFTM from the protective con­tainer. If this is the  rst time this test meter is to be used, four AA size batteries will have to be installed before it can be operated.  ese batteries are provided with the test meter.
9. Hold the SFTM in the right hand and with your thumb, press and hold the momentary switch located on the upper right side of the SFTM, see Figure 4-5.  is will turn the test meter ON and along the right side of the digital display a “0” (zero) should ap­pear. If the image of the “0” is not clear, or if many characters simultaneously appear on the display, the CONTRAST control should be adjusted.
NOTE: Under normal circumstances, the SFTM does not require calibration. To verify calibration, point the SFTM toward a  uorescent light  xture
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Table 4-5, Auxiliary gap assembly and ideal
position for source frequency test
and press and hold the Momentary Power Switch for at least 10 seconds. For power sources with 60 Hertz, the meter should read 7,200 +/- 100 and for 50 Hertz power sources, 6,000 +/- 100.
10. Locate the auxiliary gap on the excitation source component board, refer to Figure 4-4 for the location. Hold the SFTM approxi­mately 10 inches (25 cm) above the auxiliary gap with the input coupler pointing down­wards towards the auxiliary gap as shown in Figure 4-5.
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11. Press the START switch located on the front control panel, refer to the Spectroil M Operator’s Manual.  e burn cycle will be­gin and the high voltage across the auxiliary gap will appear as a concentrated stream of light. In actuality, this steam of light consists of approximately 700 high voltage discharg­es per second and the function of the SFTM is to detect and quantify these arc discharges.
12. Press and hold the momentary power switch on the SFTM after the preburn period has completed (after approximately 6 seconds). If the SFTM is properly posi­tioned to receive the light emitted across the auxiliary gap, a small red light emitting di­ode (LED) located above the digital display of the SFTM will begin to  ash at a consis­tent rate. Hold the position of the SFTM steady and continue to hold the momentary power switch and monitor the consistency of the red LED to ensure that the signal is strong and consistent. Once the burn cycle is complete (30 seconds), release the mo­mentary power ON switch of the SFTM and position it so it can be easily read.
Once the burn cycle begins, high voltage will be generated and distributed throughout the excita­tion source. Do not touch any components of the excitation source assembly while the excita­tion source is operating. Wait until the burn cycle terminates before attempting to make any adjustments. Always turn the MODE switch to STANDBY before making any adjustments.
Warning: Wear safety glasses or do not look di­rectly at the spark.  e spark from the auxiliary gap could harm your eyes if stared at for pro­longed periods of time.
Caution: Only trained personnel should carry out this procedure. It is performed in an area of the Spectroil M where high voltage potentials are present.
NOTE: It is normal to observe  uctuations of approximately +/- 1000 discharges per minute (DPM) during the measurement cycle.
If the red LED does not appear or  ashed at an erratic rate, the SFTM is not in position to permit the light from the auxiliary gap to enter the test meter. Repeat the procedure until a steady  ash­ing red light is obtained.
13. When the burn is complete, press and hold the MEMORY switch located on front of the SFTM one time. A number will appear momentarily, then the letters “LA” (last) will appear.  is number should be ap­proximately 54,000 and represents the last measurement the SFTM made before the power switch was released. T his reading is not signi cant for this procedure. Release
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the MEMORY switch to end the reading.
14. Press and hold the MEMORY switch a second time and a new number will appear.  is is the number that will be used to de­termine the excitation source frequency.  is number must be 54,000 +/- 2000. If the MEMORY switch is held, the letters “UP” will appear, which designates that this was the highest reading taken during the burn. If it is within this range, the procedure is complete; proceed with step 15. If not, the solid-state ignition circuit or high voltage capacitor may be defective, see Section 2.1.2 of the Spectroil M Maintenance Manual.
NOTE: If you press and hold the MEMORY switch a third time, the number will be the lowest measured value “DN” for the burn.  is reading is not signi cant for this procedure.
19.  is procedure is now complete.
15. Place the MODE switch to the STANDBY position. Shut down Windows and place the circuit breaker CB1 to the down position to remove power to the instrument. Remove the main power input cable by disconnect­ing the MIL-type connector from the mat­ing receptacle.
16. Press the interlock actuator inward to reset the normal operation of the switch.  is in­terlock should activate when the actuator is pressed inward to its maximum travel. Place the environmental sealing panel in position and start the six 1/4 turn pawl fasteners. Once all screws have been started, tighten all screws until they are snug, compressing the sealing gasket.
17. Install the exterior panel and secure it in position with the four Phillips head screws and dress washers.
18. Attach the main power input cable to the instrument, and plug the cable into the source of line voltage. Apply power to the instrument in accordance with all steps detailed in Section 2.1.3 of the Spectroil M Overview and System Description Manual.
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Source Frequency Test Meter || 13
Section 5
Detailed
Description
of Excitation
Source
Frequency
5.0 DETAILED DESCRIPTION OF EXCITATION SOURCE FREQUENCY
he excitation source of the Spectroil M is an oscil­lating alternate current (AC) electric arc discharge which has been optimized for oil matrices and the JOAP data base.  e excitation source is the most important subassembly of the spectrometer with regard to analytical performance (accuracy, repeatability, and JOAP data correlation).  e fol­lowing paragraphs will describe the function of the excitation source and explain factors which a ect its performance.
 e excitation source has two basic functions: 1) to provide a high voltage potential to overcome the resistance o ered by the air and oil between the graphite rod and disc electrodes which make up the analytical gap, and 2) to provide an ana­lytical potential capable of instantaneously vapor­izing the oil and any particles suspended in the oil medium.  is is accomplished with a solid­state excitation ignition circuit (SSEI) to charge a high voltage capacitor C2 until its potential is high enough to ionize the air between the graph­ite electrodes.  is ionization will appear as a high voltage arc across the analytical gap. Once the high voltage has ionized the air across the ana­lytical gap, the resistance between the gap is ef­fectively zero ohms or a short circuit to ground.  is momentary (approximately 3 microsecond) short circuit to ground is all that is necessary to discharge the potential which is stored on the ana­lytical capacitor C3.  is potential will instanta­neously vaporize the oil and any particles which are suspended in the oil at that one moment in time.  is vaporization potential will raise the en­ergy level of the valence electron(s) of the particles and when this energy is released as it returns to the ground state, it will create atomic emission which is the basis of this technique.
 is process occurs approximately 700 times per second and is referred to as the excitation source frequency.  e main reasons for the relatively high excitation source frequency are twofold:
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1) to provide a good statistical sampling of the particles spread across the disc electrode which is approximately 1/4 inch by 1/4 inch and 2) to raise the vaporization temperature su ciently to vaporize the refractory elements such as Si, Al and Ti.  is excitation frequency is regulated or elec­tronically controlled to ensure that the frequency remains constant over the complete burn cycle or from one oil type to the next. In order to allow the measurement of this excitation source frequency and still maintain optical alignment between the analytical gap and the optical processing assembly, a second gap called the auxiliary gap is designed into the excitation source and this gap is in series with the analytical gap.
 is excitation source frequency has become the standard for wear metal analysis, particularly in the United States Department of Defense (DoD) Joint Oil Analysis Program (JOAP). Over the last two decades, an extensive database of wear trends and maintenance guidelines have been established based on this excitation source characteristic and certain parameters, such as frequency.  is da­tabase has been derived based on the results of approximately 300  xed laboratory sites where actual mechanical system failures have been de­tected and the trend data leading up to the detec­tion of the impending failure have been analyzed to determine guidelines for appropriate corrective maintenance action.  ese stationary laboratories participate in a monthly data correlation program operated by the Technical Support Center of the Joint Oil Analysis Program in Pensacola, Florida. Prior to each monthly correlation data sampling or every 2000 burns, the laboratory normally has to check the excitation source frequency by us­ing an oscilloscope or SFTM.  is procedure has been referred to as checking the breaks per half cycle.
 e e ects of the physical and environmental characteristics have virtually been eliminated by the design of the solid-state excitation igni­tion circuit (SSEI).  is is accomplished by in­corporating an internally mounted ferromagnetic regulating transformer T1 which can stabilize
the nominal (120 or 240 VAC) input line volt­age having +/- 10% deviation to an output of 125 VAC within +/- 3%. However, since the high voltage transformer is simply a step-up voltage de­vice having an 80:1 ratio, it is understandable that an unstable line voltage will cause the high volt­age transformer output to vary. If this occurs, the charge stored on the high voltage capacitor will also vary thus resulting in an unstable excitation source frequency.  e frequency of the line volt­age is the second physical parameter which must be compensated for. Since the excitation source frequency is modulated from the line frequency, if the line frequency changes then the excitation source frequency will automatically change. Of course, if the components which make up the high voltage ignition circuitry were to fatigue, this will change or cause an unstable excitation source fre­quency. Last to be mentioned, but most probable to occur in application is erosion of the two 3/16” tungsten electrodes which together make the aux­iliary gap.  e auxiliary gap electrodes have ap­proximately 27,000 arc discharges during each 30 second analysis which originate from the parabol­ic tips.  is function is slowly removing tungsten material from the tips of these electrodes, which in e ect is enlarging the gap distance. As the gap distance gets larger, the resistance of the air gap is increasing and the net result is a decrease in the excitation source frequency.  is is the main rea­son that the standard operating procedure in the U.S. DoD laboratories is to perform a 2000 burn check of the excitation source frequency and reset the source frequency accordingly.
 e second parameter which can a ect the excita­tion source frequency is the environment in which the instrument must operate.  ese parameters are altitude and relative humidity, and their a ect are not easily remedied by design. In both cases, altitude and relative humidity, the resistance to current  ow o ered by the air across the auxiliary and analytical gaps can cause the excitation source to holdo .
Holdo occurs when the auxiliary gap has di ­culty breaking down.  is phenomenon is usu-
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Source Frequency Test Meter || 15
ally identi able by a pause in the time between the start of the burn and the countdown of the burn counter. While it is di cult to identify the actual cause of this phenomenon, it is believed to be in uenced by environmental conditions. To minimize this phenomenon, a set screw has been added to the auxiliary gap, Figure 3-13, to assist in breaking down its magnetic  eld. Holdo does not have an e ect on analytical results unless it ex­ceeds 2 seconds. Please refer to the troubleshoot­ing section of this manual if your instrument is experiencing holdo that exceeds two 2 seconds.
When the instrument is factory calibrated at near sea level, the excitation source is set using an oscil­loscope or the Spectro Incorporated Source Fre­quency Test Meter to the prescribed frequency. If the instrument is deployed to a higher altitude, the resistances across the gaps are reduced. With lowered resistance, the high voltage capacitor can discharge across these gaps more easily and more often within a  xed time period.  e result is an increase in excitation source frequency.
When an instrument is exposed to high relative humidity, nearly the same e ect occurs, how­ever, for a di erent reason.  e percentage of moisture in the environment makes the density of air higher and therefore o ers lower resistance to current  ow.  is allows the high voltage to conduct through the air more easily thus result­ing in an increase in excitation source frequency.  is is somewhat controlled in the Spectroil M with the incorporation of a heat exchanger which stabilizes the internal environment of the instru­ment. However, there is no humidity control in the sample excitation stand.
puter will adjust the calibration curves to make all the standards from 0 to 100 ppm read correctly. Now assume that we have an oil sample contain­ing iron wear particles.  ese particles range from 1 to 40 microns in size and are evenly distributed throughout the sample. Instrument #1 will totally vaporize all particles of iron from 0.1 to 5 microns but when a 30 or 50 micron particle reaches the analytical gap, only 10% will be vaporized be­cause of the excitation source frequency and the resident time in the analytical gap.  e analytical result for instrument #1 may be 100 ppm. Instru­ment #2 will also vaporize all particles from 0.1 to 5 microns, but will only vaporize 2% of the par­ticles in the 30 to 40 micron range.  e analytical result for instrument #2 can be perhaps as low as 70 ppm. Both instruments standardize correctly, and all standards read correctly, but they do not correlate on used oil samples because of the di er­ences in the excitation source frequency.
It is absolutely necessary to check and/or adjust the excitation source frequency prior to perform­ing the JOAP monthly correlation samples. It is also essential to check and/or adjust the excitation source frequency each and every time the instru­ment is deployed to a country where the line fre­quency is other than 60 Hertz and/or the eleva­tion or environment is di erent from the last time the frequency was set.
Maintaining the correct excitation source fre­quency is the most in uential parameter to achieving good JOAP data correlation. For sake of discussion, let’s assume that the excitation source frequency of instrument #1 is set exactly correct in accordance with Section 2.2.1 or 2.2.2, and instrument #2 is operating 20% lower than speci cation. Both of these instruments will stan­dardize without any problem because the com-
July 2010/Version 1.2
16 || Operation & User Manual
July 2010/Version 1.2
1 Executive Drive, Suite 101 • Chelmsford, MA 01824 USA
Email: service@spectroinc.com • Web: www.spectroinc.com
1.978.486.0123 • Fax 1.978.486.0030
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