Contents N500 rev. 3.1 Chapter 1 - General description ¾ Standard accessories ¾ ¾ ¾ ¾ ……………………………… Optional accessories ……………………………… Connections ……………………………………… Battery ……………………………………………... General advice ……………………………………… 1-1 1-2 1-2 1-3 1-4 Chapter 2 - General layout Keys/buttons on the control panel ………...…...……... ¾ General purpose functions …………….…..…… - Functions associated with measuring phase………. - Function "Other functions …" ………….…... - Functions operating on graphs ………….…...
Chapter 7 - Balancer mode ¾ Selection of the balancing program ¾ ¾ ¾ ¾ ¾ ………...……. Calibration sequence ……………………..………. Execution of measurement…………………….………. Unbalance measurement and calculation of the correction Splitting of correction weight ……………………… Saving of a balancing program ……………………… 7-2 7-6 7-8 7 - 10 7 - 13 7 - 14 Chapter 8 - Data manager mode ¾ Archive management ……..…………….………… ¾ Copying /shifting archive on USB key….…….….….… ¾ Sending archive to PC ……..…………….
Chapter 1 General description The N500 instrument is supplied, together with its accessories, in a special case. It is advisable, each time the instrument is used, to place back it in its case in order to avoid risk of damage during transit. Standard accessories: - Two velocity transducers dia.
Optional accessories: - acceleration transducer type TA-18/S complete with connection cable and magnetic base proximity sensor complete with stand, cable and magnetic base optical fibre photocell (60,000 RPM) complete with stand and magnetic base extension cable, length 10 metres, for transducers extension cable, length 10 metres, for photocell portable printer for direct printing of certificates on standard thermal or adhesive paper software CEMB PoInTer for data filing, management and printing. N.B.
Instead, to extract the connector, press its end part (blue or yellow) and at the same time pull the main body (grey), in order to release it. Caution: Avoid pulling the connector with force before releasing it as described above, otherwise there would be risk of damaging it. Battery The N500 instrument is provided with a built-in rechargeable lithium battery, which allows autonomy of more than eight hours under normal operating conditions of the instrument.
Caution: It is strongly recommended to recharge the battery with the instrument switched off: as recharging is completed within less than five hours such precaution prevents the battery charger from being connected for an excessively long period of time (max. 12 hours). Caution: The lithium battery is able to withstand the recharging-discharging cycles, even on a daily basis, without problems but it could become damaged if allowed to be fully discharged.
Chapter 2 General layout Keys/buttons on the control panel The control panel of the CEMB N500 instrument incorporates a keypad where the various keys or buttons can be subdivided by function: - on / off button Press this button to switch the instrument on; hold it down for at least 3 seconds to switch it off , then release the button. N.B. After pressing , the instrument is ready for use only at the end of the switching on procedure, signalled by the appearance of the home screen (see Chap. 3).
- buttons for navigating between the pages When this button is pressed in the setup screen, it confirms the settings selected and allows going onto the next screen. Instead, in the Measurement screen, it has the function of starting/stopping the actual measurement (see 2-4 Start / Stop the acquisition). N.B. To facilitate use of the instrument also with the left hand, the is located on both sides of the display.
- arrow keys When a graph is displayed, these keys increase or decrease respectively the minimum or max. value of the x axis ( , , ) or the y axis ( , ). Instead, when inputting a value for a parameter, they either shift the cursor to the left or right ( , ) and increase or decrease the value in question ( , ). - alphanumeric keypad This keypad serves for entering alphanumeric characters in the fields which do not allow just default selections.
General purpose functions In addition to many functions, specific for each different purpose and described in relative sections, there are certain general purpose functions which are described below. - Functions associated with the measuring phase Start / Stop acquisition: In all the Measurement screens, acquisition is started by pressing , and is subsequently stopped by again pressing . .
Caution: After changing the amplification, wait for a few seconds until the measurement becomes steady. - Function “Other functions...” When there are more than six functions accessible from a certain screen, there are not enough function keys to correspond to them; in such cases the key is associated with Pressing of this key causes substitution of the functions corresponding to with another five. The original correspondence can be reset by again pressing ...
Use of the cursor For easier reading and interpretation of the displayed data, it is possible to introduce a cursor in any graph, provided the visible region is not blank: this can be done with . A window at the top right corner of the graph contains the co-ordinates of the point where the cursor lies. The cursor can be shifted by one step to the right or to the left by using the following keys or respectively . For quick reaching of points from the current position, hold down or .
Change of display channel: If both measuring channels are enabled, various types of display are possible, namely: - just graph of channel Ch1 - just graph of channel Ch2 - graphs of channels Ch1 and Ch2 simultaneously The passing in sequence between the various possibilities is obtained by repeatedly pressing . This corresponds in each case to these options or General layout .
List of peaks When this function is selected, a table appears with the 10 peaks of highest value present in the zone of the spectrum displayed, and associated with the corresponding frequencies. Their value is calculated by applying an interpolation algorithm to the FFT graph; this also allows identifying peaks not situated in correspondence to one of the lines of the spectrum. When graphs). is pressed, the system quits this function and again displays the graph (or N.B.
- to save measurements The N500 instrument allows easy saving of the acquired data; for such purpose, four different archives are available for the four different types of acquisition possible: - waveform - spectra (FFT) - monitoring in time - monitoring in speed Pressing of allows displaying the archive corresponding to the measurement made.
- to capture and save displayed images In all screens of the N500 instrument, the image visible on the display can be captured with then saved in png format in an appropriate archive. This image can be used subsequently if required to accompany documentation produced by the operator. Selection of the position where to save can be done with the arrow keys and , then merely press to display a pop-up where to enter the required name, as explained in 2-3 – Alphanumeric keypad.
Chapter 3 Home screen (menu) After fully switching on the N500 instrument, it shows its Home screen which, besides showing a set of information: – Manufacturer logo and name of the instrument – Serial number (S/N) of the instrument – Current program version – Battery state: fully charged partly charged almost flat flat – instrument being charged (connection to socket via the battery charger supplied) as a normal menu, it also proposes and allows selection of the available modes, namely: - 1.
2. FFT analyzer mode - Splitting of the vibration into its component frequencies - Display of waveform of the vibration 3. Balancer mode - Balancing of rotors 4. Setup mode - Setting of the characteristics of sensors connected to the instrument - Setting of the general operating parameters of the instrument 5. Data manager mode - Data management (change of the name or delete the data saved on instrument N500) - Copying or shifting data to USB key. N.B.
Chapter 4 Setup mode Sensor setup The N500 instrument can be used with different types and models of sensors. Therefore in order to ensure correct measurement, it is necessary to preset exactly the type of sensitivity of the sensors actually connected. N.B. Although the instrument can operate correctly with any combination of sensors, it is advisable to connect sensors of the same type and model to the two channels. 1.
N.B. Although the required unit of measurement can differ from the natural one of the sensor, these are the only combinations are possible. TYPE OF SENSOR REQUIRED MEASUREMENT ACCEL acceleration, speed, displacement VELOC speed, displacement DISPLC displacement N.B. The N500 instrument is able to determine automatically whether there is no sensor connected to an enabled channel (i.e.
General Setup N.B. When the key is pressed, the SYSTEM INFO pop-up appears, containing full information concerning the system. Strike any key to close this window. The parameters for general use of the instrument should be preset in this page. 1. Date Use the alphanumeric keypad to enter the date in the format DD/MM/YYYY. 2. Time Use the alphanumeric keypad to enter the date in the format HH:MM:SS. 3. Language Select one of the possible languages: - ITALIANO - ENGLISH - DEUTSCH - FRANÇAIS - ESPAÑOL 4.
the instrument, then press end of which the pop-up to start the automatic updating procedure, at the signals successful transfer of the file and requests switching the instrument off, then on again to complete the operation. Caution: Updating of the firmware is a delicate operation, which could last a few minutes.
Chapter 5 Vibrometer mode One of the simplest, but at the same time most significant information in vibration analysis, is the overall value of the actual vibration. In fact, this is very often the first parameter to be considered when evaluating the operating conditions of a motor, fan, pump, machine tool... Appropriate tables allow discrimination between an optimum state and a good state, or from an allowable, tolerable, non-permissible or even a dangerous one. (see Appendix B – Evaluation criteria).
2. Type of measurement As with all physical quantities, vibration has a value which can vary from instant to instant: mathematically it may be described as a function of time. Hence its overall value can be calculated according to three different types: – – – RMS (Root Mean Square): This is the average value of the vibration previously squared; This is the typically used value, above all, for acceleration or speed measurements.
N.B. Use of the CUSTOM frequency band is only recommended for expert users who have sound knowledge of the basic concepts in digital signal processing. In fact, an incorrect choice of sampling parameters could lead to unsatisfactory results. For example, with too low a fmax, there is risk of losing important high frequency information; on the other hand, with too high a frequency, the resolution could be insufficient to distinguish the two peaks. 4.
10. amplification status of the channel N.B. The values obtained in this mode can be reused to evaluate the operating status of the instrument by using, for example, the tables and graphs given in Appendix B of this manual. The default measurement is that of the total vibration value, but by pressing it is possible to switch to measurement of the synchronous value: in this mode, information appears concerning the modulus, phase and speed of rotation.
When and then is selected, the entire monitoring can be saved in a file for subsequent analysis. When the acquisition is enabled for both channels, the data save is performed automatically for both channels in the same file. N.B. As access to the Monitoring in time function is gained from the VIBROMETER screen, the settings used for calculation of the overall value are the ones selected in the VIBROMETER SETUP screen. N.B.
Monitoring in speed In many situations it could prove useful to associate the vibration value with that of the speed of rotation of a shaft; in this way it could be possible to investigate, for example, how the overall or the synchronous component varies during machine starting or stop phase, with identification of any critical zones or zones with risk of resonance, which are best to avoid.
Monitoring is stopped by a further pressing of and the typical graph control functions become available (see 2-5 Functions operating on the graphs). - Set scale Show cursor Change of channel displayed List of peaks When analysis. is pressed, the entire monitoring can be saved in a file for subsequent When the acquisition is enabled for both channels, the data save is performed automatically for both channels in the same file. N.B.
Chapter 6 FFT (Fast Fourier Transform) analyzer mode A complete analysis of the vibration cannot fail to take into account the study of the various factors contributing towards forming its overall value. Hence it is essential to be able to carry out spectrum analysis with FFT (Fast Fourier Transform) algorithm. Such technique allows splitting and memorizing a measured signal into its component frequencies in a certain period of time, thus making it easier to discover their causes.
2. Type of measurement This is the mode in which each component (line) of the spectrum is applied; it can be: – RMS (Root Mean Square): This is the one most typically used, as it is associated with the overall RMS value. – PK (Peak): This is the maximum value reached by the component in question in a certain interval of time; it is rarely used because it does not provide information about the overall PK value; line by line it is simply equal to the RMS value multiplied by 1.41.
5. N° of lines Such parameter defines the number of lines used in the FFT algorithm, in practice associated with the resolution in frequency in the spectrum. This determines how close can be the frequency of two peaks so that they still remain distinct in the FFT graph. Such resolution is equal to f max N linee therefore to maintain it constant, when the max. frequency is increased, likewise the number of lines should be increased.
Spectrum analysis (FFT) The so-called FFT algorithm is applied to the signals acquired with due respect for the settings made; in accordance with the recommendations deriving from the mathematical treatment from which it has been taken, such numeric processing is preceded by application of a Hanning window to the acquired signal. This allows attenuating the edge effects due to digitizing as well as reducing phenomena of leakage in the spectrum. The Measurement page appears like the one shown in the figure.
Harmonic cursor When the cursor is displayed on an FFT graph (see. 2-6 Use of the cursor), it means that a special mode known as harmonic cursor is available.
Waveform function In the second series of functions (accessed by pressing ) is present which allows access to a page where the vibration signals are shown in relation to time. In this mode, the N500 instrument can be used as an actual oscilloscope, and further enhances the variety of information which can be deduced from the vibration signals. This mode also contains all the typical graph control functions (see 2-5 Functions operating on graphs).
One of the most frequent uses is the so-called Impact test: A hammer is used to stress a structure and to cause it to vibrate in order to determine its natural frequencies. For such purpose, a sensor should be placed in the zone to be examined and a threshold value chosen, which is higher than the background noise read, but lower than that produced by the hammering with which the structure is stressed. N.B.
When the trigger is enabled, the following settings become visible in the TRIGGER SETUP page: – Channel – Threshold 2. Channel This indicates on which channel (Ch1 or Ch2) to make the comparison between the signal value and the threshold value in order to activate the acquisition. N.B. If just one of the two measuring channels is enabled, obviously choice of the trigger channel is obligatory, hence it is forced automatically. 3.
After pressing the threshold value can be preset in two ways, namely: – By typing, using the numeric keyboard (only after pressing to shift the broken line in the graph); , it is possible – by using and to increase or decrease the value of a single digit, which can be selected with and (the broken line in the graph is shifted immediately, however at the end, pressing of is always necessary in order to confirm). N.B.
6 - 10 FFT analyzer mode
Chapter 7 Balancer mode One of the causes of vibration most frequently encountered in actual practice, is the unbalance of a rotating part (lack of uniformity of the mass about its axis of rotation); such unbalance can be corrected with a balancing procedure. The N500 instrument allows balancing any rotor under service conditions in one or two planes, by using one or two vibration pick-ups and a photocell.
As the calibration is normally a laborious procedure, the parameters derived should be memorized, then called in the case of subsequent maintenance work on the same machine. This is possible via the balancing programs: a program is defined with a series of settings in order to work on a particular rotor and it contains all the information and data acquired regarding such rotor. It is possible to save the current program at any moment in a special archive so that it is available at later dates. N.B.
1. New program – BALANCING SETUP The creation of a new program entails setting of a series of parameters. This is done in the BALANCING SETUP screen. 1. Number of planes This is the number of planes on which to act to correct the unbalance of the rotor. The number can be 1 or 2. 2. Filter accuracy Balancing under not particularly stable signal conditions is certainly critical and needs acquisition for longer times in order to obtain a satisfactory quality of the value measured.
For example, for a rotor with speed of rotation 600 RPM, it could be necessary to wait up to 10 seconds before being able to view the first result of the measurement. 3. Unit of measurement of the vibration This is the unit of measurement in which to supply the vibration to the sensors: – acceleration (g (acc)) – speed (mm/s, inc/s) – displacement (µm or mils) N.B.
2. Load program from archive When this option is selected, access is gained to the program archive. Arrow keys and allows scrolling the 10 available positions, thus selecting the required program (visible in negative, i.e. with white writing on black background); the program can then be loaded by pressing . If it is not possible to carry out the operation correctly (e.g.
Calibration sequence The calibration operation, necessary for assessing the unbalance of a rotor, is normally a procedure consisting of various steps.
1 - number and name of the balancing program (if loaded from the archive), or else ---2 - current speed of rotation, in RPM 3 - layout of the position of the sensors and correction planes on the rotor; indication of the plane on which to apply the test weight N.B. This representation is approximate only; the sensors and correction planes can be chosen in any position relative to each other (external sensors or sensors inside planes, ...
Execution of measurement To start the measurement in any of these steps, press ; a pop-up panel appears showing, in real time, the quality of the current measurement (for each channel). The higher is the level of the bars, the better will be the quality of the measurement (which is averaged over time). After reaching the required level, stop the measurement again by pressing .
Test weight Calibration requires the use of a test weight, to be applied in succession on the various correction planes. These two parameters should be preset, with the appropriate and by typing the appropriate values with the numeric functions keypad, and confirming with . To cover the various operational requirements when balancing on two planes, it is possible to specify a different test weight (value and angular position) on plane 1 and on plane 2. N.B.
Unbalance measurement and calculation of the correction In appearance the UNBALANCE MEASUREMENT page is very similar to the calibration page: 1 2 3 6 4 5 7 8 1 2 3 4 6 7 5 8 and the following information is given: 1 – number and name of the balancing program (when loaded from the archive), otherwise ---2 – current speed of rotation, in RPM 3 – layout of the position of the sensors and correction planes on the rotor N.B.
4 – indication of the correction weight, in value and position on every plane. N.B. The module is indicated in general units U, corresponding to those used in setting the test weight. As the program makes use of correction through addition of material, the position indicated is the one where to add the correction weight.
: direct printing of a balancing certificate by using the portable printer provided (optional). The certificate gives the unbalances on the correction planes (in units U), as well as the values of vibration (overall and synchronous) of these planes. The following is an example of this certificate: : function involving splitting of the correction weight on two presettable angles (see 7-13 Splitting of correction weight.
Splitting of correction weight In this page it is possible to select between the correction modes: - by addition of material - by removal of material By pressing push buttons and respectively. In certain practical situations it is not possible to correct in the position calculated theoretically as optimum position: in the case of a fan, for example, such position could fall in the gap between two blades, where obviously it is not possible to add or remove material.
Caution: Whatever the value of α1 and α2, the angle of revolution is subdivided into two parts, one part convex (<180°) and the other concave (>180°). In order to carry out the splitting, angles α1 and α2 should be chosen so that the correction position calculated during balancing, lies within the convex zone. If not, such splitting would be impossible, and the N500 instrument would indicate zero as correction weight for both positions α1 and α2. N.B.
Chapter 8 Data manager mode The N500 instrument allows saving the measurements made (FFT, waveforms and monitoring) in special archives, which can be managed through this special function directly accessible from the home screen. a MEASUREMENT ARCHIVE screen appears where it is Upon pressing possible to select between the following possibilities: – Data management (i.e.
When one of the archives in selected in the SELECT DATA MANAGER screen, its contents will be displayed making distinction between empty positions (-----), and occupied positions (name, date and time of save). After selecting one of the items of data, the latter can be renamed or eliminated (to free space) if it no longer serves. To fully clear the archive, press then confirm by pressing . N.B.
After inserting the pen drive in one of the two USB ports on the instrument it is necessary to select which archive/archives to be transferred. These will be marked with the symbol placed alongside its/their name. causes starting of the data transfer process, indicated by the Pressing of pop-up wait message At the end, the symbol indicates that the operation has been concluded successfully. Instead, any errors are given in the same pop-up message alongside the symbol Data manager mode .
Caution Never extract the USB key while the pop-up wait message is showed and before proceeding, wait at least for its led to flash slowly. If flashing is rapid, it means that the data transfer is still in progress and extracting the pen drive could block the system, besides causing data loss. In such case, it could be necessary to reboot the instrument.
Display of measurements present in the archive It is possible to display all the measurements and images saved in the N500 instrument by selecting them from the relative archive and pressing This makes it very easy to obtain comparisons and to make assessments directly "in field ". The various data are presented in screens wholly similar to the corresponding measurement screens.
8-6 Data manager mode
Chapter 9 CEMB PoInTer Program (optional) The data collected and memorized with the N500 instrument can readily imported to a PC (directly or using a USB key), and subsequently analyzed, processed, compared, printed. Such operation is considerably facilitated by using the CEMB PoInTer (Portable Instruments Terminal) software, available for Windows operating systems.
Installation and registration For installation of the CEMB PoInTer software, proceed to run the setup.exe program, contained in the CD-ROM, and then click on the button without changing any option. In this way the software will be installed in the default program directory.
N.B. To ensure correct installation and activation of the product, it is advisable to have the Administrator rights on the PC used; this is possible by making a login as Administrator user. Caution: Installation of the CEMB PoInTer software requires a different activation code on each PC, each one of which must be requested from CEMB by the abovementioned procedures.
Data Manager The archive can be fully handled with just a few simple operations using the mouse: - Select an item : click on the name; - expand / close a node (i.e. display or hide its children) : double click on the name or click on the symbol ; - add an item : click on and type its name; - eliminate an item (with all its children) : click on - rename an item : click on - copy a point : click on , then confirm when asked; and type its new name; ; N.B.
Caution: The measurement settings are essential data for a point. For this reason they must be modified after the creation of the point. In the case of incorrect entry, the point should be eliminated and then recreated. N.B.
Reading measurements saved on the N500 instrument CEMB PoInTer software allows you to import measurements saved in the N500 instrument directly to the PC using the connection cable provided for this purpose. To perform this operation, connect the instrument to the PC’s serial port, then press to start communication. Messages and information related to the communication status will be displayed in a dedicated pop-up window.
Loading of new measurements in the archive New measurements can be loaded into the archive from a USB key (see 8.2 Copying/shifting archive on USB key), or from those imported directly from the N500 instrument and saved in a temporary directory (see previous paragraph).
Selection and elimination of measurements A measurement can be eliminated by selecting it with a click and by pressing the key located under the list of measurements; this causes opening of a pop-up which requests explicit confirmation before proceeding to the deleting operation. Such operation, which causes data loss, is only allowed with the padlock open (see 9-5 Data Protection Password).
Display of graphs 4 2 3 1 5 5 1 – area of the graph 2 – list of measurements plotted (indicating the channel to which they belong) 3 – information regarding the cursor - measurement with which it is associated - point of the archive to which such measurement belongs - current co-ordinates - keys or buttons to shift it 4 – graphic functions: - dragging of cursor - zoom - shifting of graphs in the window 5 – general functions - return to main screen “Data Manager” - separate / combine graphs - add notes -
Cursor A cursor is present on the graph. This cursor is associated, by default, with the first measurement plotted. This can be changed by clicking on the graph with the right mouse button and making the required selection in the contextual menu. The cursor can be shifted by one step at a time either to the left or right with or else by pressing the arrow keys on the keyboard.
Shifting the graphs in the window After selecting it is possible to click on a point of the graph, then by holding down the mouse button, the entire graph can be shifted within the window. In practice, this corresponds to changing the minimum and maximum limits of both axes, without this, however, altering the scale. When the cursor is moved outside the window, the graph returns to the position prior to the shifting. N.B.
Creation and printing of certificates and reports Use of the CEMB PoInTer software allows easy creation and printing of vibration analysis certificates and reports, including data and/or graphs of the measurements taken and saved using the N500 instrument. When the key is pressed, the user must select the model (template) required for the certificate to be produced. This model is a simple HTML file that the same user can create as required using any type of HTML editor or a word processing program (e.g.
Appendix A Specification - Instrument - Dimensions: approx. 230 x 230 x 58 mm - Weight: 1.75 kg - Operating range - Temperature: from -10° to +50° C - Humidity in air: from 0 to 95% without condensation - Power supply - Rechargeable lithium battery, 6 Ah - Charging time: less than 5 hours (from fully discharged battery) - Power supply unit-battery charger for 100-240 V, 50/60 Hz (24 V, 1.5 A) - Autonomy: over 8 hours with normal use of the instrument – - Display ¼ colour VGA TFT 320x240 – 5.
- Measurement specifications - A/D converter: resolution 24 bit - Dynamic range: > 100 dB - Number of averages: from 1 to 16 - Resolution: 100, 200, 400, 800, 1600, 3200 lines - Frequency range: DC – 15kHz max - Background noise: typically less than 1.50 µV for a spectrum with 400 lines having a max. frequency of 1 kHz - Window: Hanning (always enabled) - Speed of analysis: 2.
Appendix B Evaluation criteria TABLE A MACHINE CATEGORIES BY EVALUATION CRITERIA Group according to ISO 10816 VDI 2056 I–K II – M III – G IV – T V–D VI – S MACHINES Machine parts that are closely related to the machine as a whole during normal working conditions. Grinding and boring machines. Electric motors (up to 15 KW) that need good balancing, e.g. dentist’s drills, aerosols, high quality electromedical and domestic appliances. Jet engine turbines and compressors. Fast compressors.
EVALUATION CRITERIA BASED ON THE VIBRATION MEASURED ON FIXED PARTS SPEED OF For almost all machines, the measurement of the total speed of vibration as RMS value on fixed parts of the structure is able to characterize the machine from the vibratory point-ofview. The total value is calculated in the frequency range 10 to1000 Hz or else, for slow machines (< 600 RPM) in the range 2 to 1000 Hz. Reference is made to the max. speed on the support in the three directions of measurement.
not admissible accettable admissible RMS velocity (mm/s) good uman sensitivity Graph for evaluating mechanical vibrations on the basis of the RMS velocity.
B-4 Evaluation criteria
Appendix C A rapid guide to interpreting a spectrum TYPICAL CASES OF MACHINE VIBRATIONS 1. PRELIMINARY RAPID GUIDE f = vibration frequency [cycles/min] or [Hz] s = shift amplitude [µm] Measured values during control: v = vibration speed [mm/s] a = vibration acceleration [g] n = piece rotation speed [rpm] Frequency data Causes Notes 1) f = n Unbalances in rotating bodies. Intensity proportional to unbalance, mainly in the radial direction, increases with speed. Rotor inflection.
7) f is much greater than n, not an exact multiple 8) f = natural frequency of other parts 9) f unstable with knocking Damaged roller bearings. Unstable frequency, intensity and phase. Axial vibration. Excessive wear on sleeve bearings. Completely or locally defective lubrication. Belts too tight. Characteristic audible screech. Multiple belts not homogeneous. Run between the belts. Low load gears. Teeth knock together because of insufficient load; unstable vibration.
2. TYPICAL SPECTRA OF VIBRATIONS RELATED TO THE MOST COMMON DEFECTS Note: The spectra are in an indicative graphic form. The N500 equipment produces a different form of graph. The following are the spectra of typical vibrations, caused by the most common defects found in practical experience. CPM = shaft rotation speed in rpm 1. UNBALANCE 2.
3. MECHANICAL LOOSENESS/PLAY 4. BELT 5.
6. SLEEVE BEARINGS 7. ROLLER BEARINGS 8.
3.
Appendix D Codes that can be used in models for certificates obtained using the CEMB PoInTer program. When the certificate is created, the CEMB PoInTer software automatically replaces some of the default codes in the model (#x# format) with corresponding information, related to the measurements displayed at the time.
D-2 #251# Point that measurement 1 is taken from #252# Point that measurement 2 is taken from #253# Point that measurement 3 is taken from #301# Total (overall) value of measurement 1 #302# Total (overall) value of measurement 2 #303# Total (overall) value of measurement 1 #351# Unit of measurement for the y axis for measurement 1 #352# Unit of measurement for the y axis for measurement 2 #353# Unit of measurement for the y axis for measurement 3 #401# Frequency of peak no.
#526# Value of peak no. 1 in graph 3 #527# Value of peak no. 2 in graph 3 #…# Value of peak no. .. in graph 3 #550# Value of peak no.
