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Summary of Contents for KOHTECT BT-77
- Page 1 BT-77 Bearing Tester with Non-Contact Tacho Operating Instruction Manual...
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Page 3: Table Of Contents
KOHTECT BT-77 CONTENT Page INTRODUCTION................1 1.0 BT-77 INSTRUMENT DISCRIPTION AND FUNCTION....1 1.1 Specification 1.1.1 Standard Condition for Operation 1.1.2 System Specification 1.2 Overview on Rolling Bearing Condition Monitoring 1.3 Understanding Shock Induced “Carpet value” and “Maximum value” 1.4 Tachometer 1.5 Design of BT-77 1.5.1 Operation Keys 2.0 TAKING MEASUREMENT WITH THE INSTRUMENT....7 2.1. Instrument display and measuring modes 2.1.1 Setting the system real time and date 2.2 Taking Bearing Diagnosis Measurements 2.2.1 Selection and setting up the measuring points 2.2.2 Set up initial parameter & taking bearing measurements 2.2.3 Taking bearing diagnosis measurement and save 2.2.4 File format and open measured file 2.3 Evaluation of the Measuring Results 2.4 Measuring RPM by Tachometer 2.4.1 Set up instrument and measuring RPM 2.4.2 Measuring RPM by the Tachometer 3.0 ROLLER BEARING CONDITION MONITORING BY THE SHOCK PULSE METHOD (MEASUREMENT METHOD)..14 3.1 What is Shock Pulse Method (SPM) and it basis 3.2 How Shock Pulse Measured and Evaluated for Rolling Bearing 3.3 Evaluation of Bearing Condition with BT77 3.4 Method and measurement location of the bearing 4.0 DELIVERY.................19... - Page 4 KOHTECT BT-77...
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Page 5: Introduction
KOHTECT BT-77 INTRODUCTION This manual is intended for the study of the BT-77 bearing condition tester. The manual contains description of the BT-77 bearing checker operating principle, operating procedures of the intended use and bearing shock pulse evaluation concept. 1.0 BT-77 INSTRUMENT DISCRIPTION AND FUNCTION 1.1 Specification 1.1.1 Standard Conditions for Operation: • Operating temperature (device & sensor), -10 to 55°С, (±5)°С; • Relative humidity 80% at temperature 30 °С; • Atmospheric pressure, 84 to 106.7 KPa (630 - 800 mm Hg); • Resonance frequency, 32 kHz; • Measurement unit, dB , dB , dB • Range, max. 99dB; • Resolution, 1 dB; • Accuracy, ± 5%; • Operating temperature (tacho), 10 to 55°С, (±5)°С;... -
Page 6: Overview On Rolling Bearing Condition Monitoring
However, manufacturing defects, damages, which appear during operation, dirt in the bearing, insufficient or incorrect lubrication – all these factors cause the collision of the bearing elements and, as a result, acoustic oscillations of a wide spectrum are generated in the bearing body. A specially designed transducer (patent №18652) is used to filter out the part of this spectrum that carries information on the bearing faults detection. The transducer filters those acoustic oscillations which are generated by the bearing defects, and converts them into electronic signal proportional to the magnitude of shock pulse signal, that is amplified and measured by the BT-77 electronic unit in the relative units of decibels (dB). A real new bearing is just from the beginning of its use, a source of induced vibration, the amplitude of the shock pulse of which is dB The dB , initial value depends on the large number of factors; however, in practice it is possible to limit them to diameter D (mm) of the neck and its rotating speed � (rpm). The... - Page 7 KOHTECT BT-77 value of dB features the condition of a new correctly installed and lubricated bearing. The shock pulse amplitude increases as a result of wear and improper use. Shock acceleration amplitude over running the value of dB - dB features a damage, and is used for the evaluation of bearing condition. This enable BT-77 to tell the difference of shock pulse values induce is low shock and high shock, a normalized measurement scale call dB is uses, see beneath Table-1.0. 0 - 25 Good condition 25 - 40 Satisfactory condition > Poor condition, breakdown risk Table-1.0 Fig-1.0...
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Page 8: Understanding Shock Induced "Carpet Value" And "Maximum Value
KOHTECT BT-77 50 - dB - absolute value at measuring point 40 - dB - value features bearing failure (dBa - dBi) 30 20 - dB - original value of the shock acceleration amplitude 10 - 0 - response threshold of the bearing checker -5 -10 Figure-1.1 - An example of these values ratio. Pattern of the induced oscillations, which are registered by BT-77, changes according to the bearing faults. 1.3 Understanding Shock Induced “Carpet value” and “Maximum value” At the measurements, the bearing checker allows to filter out and measure two specified values of the shock acceleration amplitude: the Carpet value (dB ) and the Max. value The dB background value (the Carpet value) refers to the frequent collisions of the... -
Page 9: Tachometer
KOHTECT BT-77 For instance, at the shock acceleration amplitude measuring of a well lubricated and correctly installed bearing, the dB is only slightly higher than dB . But when one measures shock acceleration amplitude of a bearing having faults, these faults are detected by dB maximum values, at that, the background dB value depends on the lubrication condition, and can grow increase substantially when there is insufficient lubrication followed by frequent metal-to-metal contacts. -
Page 10: Design Of
KOHTECT BT-77 contrast when taking RPM measurement. The measured RPM reading can also be saved within the device with file name end by “tac” extension. 1.5 Design of BT77 Constructively BT-77 Bearing Tester is designed in a light and strong alloy casing protected by silicon sleeve with the rechargeable internal battery power supply, socket for the measuring probe and USB port for tachometer sensors or file upload to PC for data management. The controls and connectors location is shown on the Fig. 1.2a & Fig. 1.2b. Fig. 1.2a Fig-1.2b Top view of BT-77 1. BT-77 device 2. Bearing shock pulse measuring probe 3. Tachometer sensor and magnetic stand 4. Socket for measuring probe 5. USB port for Tachometer sensor/ PC com 6. Socket for AC charger 7. Soft membrane push pad for operation 8. Back-lite monochrome LCD display... -
Page 11: Operation Keys
KOHTECT BT-77 1.5.1 Operation Keys Turn O� Enter setup menu OK / Start Return / back to earlier step Adjust up or increase Adjust down or decrease/ OFF (press and hold) 2.0 TAKING MEAUSREMENT WITH THE INSTRUEMNT Before using the instrument, it is a good practices to check proper mechanical functioning of the controls, connectors and power state when switch on. Note the device automatically switches off after 150 seconds when no further operation. 2.1 Instrument Display and Measuring Modes To switch “O�” the BT-77 bearing tester, press . The device perform self test as shown in Fig-2.1 and automatically enter the first default operation mode - USB interface, Fig-2.2. To connect device to PC for report print and view, make sure device is set in USB interface mode and press to ready for interface. Connect the USB cable between device and PC via the USB port. -
Page 12: Setting The System Real Time And Date
Mount the stationary extenders (pins or bolts 6-8 mm) of desired length or provide holes for measuring probe access in the bearing housings located behind the machine protective gears or caps. ATTENTION! Keep the probe location and the force the same during the measuring cycle! The BT-77 Tester automatically switches off after 150 seconds when no further operation. - Page 13 KOHTECT BT-77 2.2.2 Set up initial parameter & take bearing measurements • Press to turn on BT-77, press key to switch display to bearing diagnosis measurement mode shows in Fig-2.3. • Press to begin new measurement shown in Fig-2.4 and press again to start taking reading. B e a r i n g s 7 7 D 1 1 = = = = = = = = = = = = = = = = 2 .
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Page 14: Taking Bearing Diagnosis Measurement And Save
KOHTECT BT-77 diameter or shaft diameter “D” and RPM, “N” speed for the machine. ATTENTION! Measurement calculation method: Single - single reading with dB taken into account. Result – normalized value of , dB for condition evaluation based on the technology developed by the Central Research &... -
Page 15: File Format And Open Measured File
“xxx.b77”or “xxx.tac” extension) to be saved, see Fig-2.6 in section 2.2.4 save measured file. • Press to confirm data saved. 2.2.4 File format and open measured file For BT-77, any measured reading on display reading is saved within the device in standard format with self device generated directory or file names in term of date and time (“0325” mean 25 March and “165301” mean 16hrs, 53 mins, 01 sec) follow by “b77” extension format for data file, see Fig-2.6. Main directory name / 0 3 2 4 _ 1 7 0 4 0 5... -
Page 16: Set Up Instrument And Measuring Rpm
KOHTECT BT-77 The measuring results are recorded into the report. While continuously monitoring the equipment condition, it is recommended to use the records as graphical data representation to show clearly the tendency of condition change at the measuring points. Table-2 Pump inventory numbe1121r Bearing № 1 Bearing № 2 Bearing № 3 Bearing № 4 Date 10 30 50 10 30 50... - Page 17 2.4.2Measuring RPM by the Tachometer • Press to turn on BT-77, press key to switch display to Tachometer measurement mode shows in Fig-2.7a. T a c h o m e t e r T a c h o E P C = 1 3 0 0 4 . 8 1 R P M 2 .
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Page 18: Roller Bearing Condition Monitoring By The
KOHTECT BT-77 3.0 ROLLER BEARING CONDITION MONITORING BY THE SHOCK PULSE METHOD (MEAUREMENT METHOD) 3.1 What is Shock Pulse Method (SPM) and it basis Designation of the Shock Pulse Method (SPM) is a signal processing technique used to measure rolling bearing condition and the quality of their lubrication in the motor, pumps, separators, turbo compressors for diesel boost, etc. Using the instruments to measure shock pulses, one can determine the air or gas leaks via looseness in the high-pressure vessels or pipes. The research work conducted at Central Research &... -
Page 19: How Shock Pulse Measured And Evaluated For Rolling Bearing
KOHTECT BT-77 can be easily filtered out all other vibrations, i.e. vibration frequencies. The shock pulse method involves monitoring and analyzing the decaying transient process. 3.2 How Shock Pulse Measured and Evaluated for Rolling Bearing The outer raceways of the bearing always feature roughness. Therefore a bearing under normal operating undergoes the mechanical impacts and creates shock pulses. Shock pulse value is dependent on the bearing surface condition and the peripheral condition of the bearing. Shock pulse value of the regular bearing features 1000 times increase since the time a bearing is new up to the moment when a bearing needs replacement. Because of the very large dynamic range shock pulses are measured on a decibel scale. Empirical tests showed that even the new and lubricated bearing generates shock pulses. The value of this initial impact is set as dB (dB, initial value). As the bearing wears, the value dB (average shock pulse value) increases. �ormalized value dB... - Page 20 KOHTECT BT-77 < Good condition = 20 - 40 Satisfactory condition > Poor condition (i.e. bearing need replacement) Table-3 3.3 Evaluation of Bearing Condition with BT-77 Technical condition of the bearing is mainly determined by the level and relation of two measuring values dBm and dBc. - maximum value of normalized signal in decibel. - carpet value of normalized signal in decibel (background of the bearing). However, under the work of the bearing the peak strikes have not only varying magnitudes, but frequencies as well. Fig-3.2 shows the typical examples of the...
- Page 21 KOHTECT BT-77 1. Good bearing generates mainly shocks in the interface between the loaded rolling element and the raceway. These shocks create normal background level with low carpet value (dB < 10) and random strikes with maximum value dB < 20 dB. 2. When the defects occur on the outer raceway of a bearing or a bearing element, the general background features peak signals with Max ��alue dB > 40 dB. The collisions happens randomly, quite often their carpet values stand within the limits dB < 20 dB. Though when the bearing failure occurs, the carpet value can be decreased. As a rule, a great difference between dB and dB values occurs. 3. When there is no lubrication supply or tight (loose) roller bearing fit, the Carpet ��alue will reflect this by increasing (dB > 10), even there are not any defects on the outer raceway of a the bearing. The Max ��alue and the Carpet ��alue are relatively close (dB = 30, dB = 20). 4. Under pump cavitation both backgrounds feature high magnitude value. Shock pulse standards on pump cavitation are published. The measurements are taken on...
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Page 22: Method And Measurement Location Of The Bearing
KOHTECT BT-77 Driving gear failure in the gear box also can cause the periodic strikes. These strikes will be rhythmic in respect to the shaft speed (on all bearings installed in the gear box). Don’t take measurements when you start the motor or you just applied the lubrication (complete it in 15 minutes). Table-3.2 shows mentioned above and other possible cases of increased values of shock impulses. It may happen that a new bearing may have the Carpet ��alue dBc more than 20 dB. If these values are stable within some time interval, bearing condition is acceptable. 3.4 Method and measurement location of the bearings Shock pulse measurements should be completed on the bearing housing. When free access to the bearing housing, use the measuring probe as shown in Fig-3.3a, 3.3b 3.3c and Fig-3.3d. -
Page 23: Delivery
KOHTECT BT-77 Fig-3.3c Shock pulse zones. 1 - ��ibration measuring probe 2 - Bearing housing 3 - Stress wave propagation 4 - Defective rolling bearing 5 - Shock pulse measuring zones (Bearing load zone) Fig-3.3d 4.0 Delivery Set № Description Qty �ote 1. BT-77 w/ rechargeable battery inserted 2. Bearing ��ibration measuring probe 3. IR Tachometer w/ mounting stand 4. AC Charger, 220-230��olts 5. Liquid maker 6. Carrying Case with Foam-insert 7. Operating Instructions Manual in CD-ROM 1 8. CD-ROM PC software 9. USB PC communication cable 10. Maker calibration certificate Table 4.0...
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