Portable equipment N300 Vibrometer Balancer USER INSTRUCTION
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Table of contents N300 rev. 1.2 Chapter 1 - General description ¾ Standard accessories ¾ ¾ ¾ ¾ ¾ ¾ ……………………………… Optional accessories ……………………………… Inputs ……………………………….……… Reset button ……………………………………… Battery ……………………………………………… Adjustment and calibration…………………………. ..… General advice ……………………………………… 1-1 1-2 1-2 1-3 1-4 1-5 1-5 Chapter 2 - General overview ……………………………………………... 2-1 Start / Stop acquisition functions ……………………… ¾ Changing the channel displayed ………………….…...
Chapter 6 - Balancing function ¾ Imbalance measurement and correction calculation.……….. ¾ Additional functions ………………………………… ¾ Displaying balancing results from the records ……….… ¾ Measurement settings ………………………………… 6-3 6-5 6-5 6-7 Chapter 7 - CEMB N-Pro program (optional) ¾ System requirements ¾ ¾ ¾ ¾ ¾ ¾ ¾ ¾ ¾ ¾ ¾ …………………………….… Installation of the software ……………………….
Chapter 1 General description The N300 instrument and its accessories are supplied in a strong, solid case designed to withstand demanding environments (steelworks, refineries, workshops, etc) and air travel. It can also be locked with a padlock for greater security. We recommend the instrument is returned to its case after every use to protect it from damage during transport.
Optional accessories: - diameter 40 velocity transducer complete with connection cable, magnetic base and probe optic fibre photocell (60,000 RPM) complete with upright and magnetic base 10m-long extension cable for transducers 10m-long extension cable for standard photocell 1 USB data cable CEMB N-Pro software for saving, managing and printing data.
To extract the connector, press the terminal part (blue or yellow) and simultaneously pull the main body (grey), to release it. Warning: Do not try to pull the connector out with force without releasing it as described above as it could damage it. Reset button In some special circumstances, CEMB customer service may advise you to reset the N300 instrument. To do this, press the button located on the lower part of the instrument using a small object with a rounded tip.
Battery The N300 instrument is equipped with an integral rechargeable lithium battery, offering a battery life of more than ten hours under normal operating conditions. The battery status is indicated by an icon in the upper right hand corner of the screen. battery fully charged battery partly charged battery almost flat (battery life remaining when this appears is approx.
Warning: Recharge the instrument before storing it if you do not intend to use it for a long period of time. In this case, remember to recharge it every 3 months: the internal clock also consumes power (even though the amount consumed is low), therefore after a long period of disuse it is possible that the battery will be flat.
1-6 General description
Chapter 2 General overview Keypad The keyboard on the CEMB N300 instrument has a limited number of keys, enough to guarantee easy and intuitive use. - on/off key Press this key to turn the instrument on; hold it down for at least 3 seconds to turn it off, then release the key. Note: After pressing , the instrument’s serial number and the version of the firmware installed will be displayed briefly in the lower part of the screen.
- back key Press this key to quit the current screen and return to the previous one. It can also be pressed when setting parameters to end the operation without changing any values. - function key (F) When available, it displays the additional functions bar in the lower part of the screen. - set key (SET) In the settings screen it enables the “edit” function for the parameter selected. In the Vibrometer and Balancing screens it enables the “edit” function for all of the measurement parameters.
Start/Stop acquisition function In all measurement screens acquisition is started by pressing pressing the same and is later stopped by . The acquisition enabled status is easy to identify by the presence (in the upper left hand corner of the screen, below where the channel displayed is indicated) of an arrow rotating to describe a circumference.
- List of peak values When selected, this function displays a table containing the amplitudes of the highest components of the signal, with the corresponding frequency listed beside each one. Up to five peak values are listed in descending order, irrespective of their frequency. If the signal measured is composed of a lower number of significant components, a lower number of peak values will be displayed. Use the peaks.
- YY are the last two figures of the year (08 for 2008, 09 for 2009, …) HH is the time of day (from 00 to 23) mm are the minutes of the hour (from 00 to 59) The position to open can be selected using the and arrows, then the additional functions bar must be displayed and one of the following operations must be selected: - save the measurement (or balancing operation) performed. The current date and time are automatically used to identify the data recorded.
Note: Before deleting data from the records, the symbol asks the operator to confirm the operation, which will result in the data being deleted definitively. Press the key to confirm; with , the data will not be deleted. Note: The and keys, which respectively increase and decrease the position selected by 3, can be used to scroll through the records quickly.
Chapter 3 Initial screen (menu) When turned on, the Instrument model N300 displays the main screen containing the CEMB symbol, the instrument’s name, the battery status, the date and time and the icons used to access the various pages: – – – Vibration measurement Balancing General settings (setup) After selecting the desired page using the and arrows, press to open it. 1.
The data transfer function, identified by a relative screen, opens automatically when a USB cable is inserted into the port of the N300 instrument and that of a PC whilst the first screen is displayed. In this state the PC acts as master, whilst the N300 instrument acts as a simple slave, therefore pressing keys no longer has any effect. Once the data has been transferred to the PC (see Chapter 7–6 Reading data from the N300 instrument), disconnect the USB cable to return to the main panel.
Chapter 4 Setup function All of the parameters required for correct operation of the N300 instrument can be set in the setup screen. You can scroll up and down the list of parameters that can be set using the and arrows. The parameter selected will be displayed in white on a black background (in negative). To edit the value press the then confirm with the key, insert the desired value when requested to do so, key. To quit the edit function without changing the previous value press .
Note: Although the instrument can operate correctly with any combination of sensors, we recommend that sensors of the same type and model are connected to the two channels. For both possible types: - accelerometer velocimeter displacement ACC VEL DIS two different sensitivity levels can be set, identified respectively by “1” and “2”.
Time Time must be entered in the N300 instrument using two figures for the hours (from 00 to 23) and two for the minutes (from 00 to 59). To assist the operator, the hh:mm format is displayed below the current time. New values can be entered following the same procedure as that described above for the sensitivity of the sensors (see above).
Chapter 5 Vibrometer function One of the simplest, but at the same time most important, values in vibration analysis is the overall value of the vibration itself. This is often the first parameter to consider when assessing the operation of a motor, fan, pump, machine tool, etc. Suitable tables are used to discriminate between an excellent condition or a good, acceptable, tolerable, unacceptable or even dangerous condition. (see Appendix B – Judgement criteria).
1. Enabling/Disabling a channel: Each of the measurement channels of the N300 instrument can be: enabled when you wish to connect a sensor and take a measurement disabled when no sensor is connected - In the event that a channel is disabled, all of the other measurement settings disappear, and pressing displays the OFF message. 2. Sensor type: One of the sensors for which the sensitivity has been set must be selected (see 4.
5. Type of vibration Like all physical sizes, vibration has a value that can vary from one moment to the next; mathematically it can be described by a function of time. Its overall value can therefore be calculated in three different types: − − − RMS (Root Mean Square): mean square value the mean value of the previously squared vibration; the most commonly used, especially for acceleration or velocity measurements.
that even the high-frequency zone, where bearing-related problems usually occur, can be included in the spectrum. Note: Other things being equal, the selection of a low maximum frequency (less than 1000 Hz) considerably lengthens the amount of time required for acquisition and measurement. 2. No. of averages Shown next to the N symbol, it indicates the number of spectrums that must be calculated and averaged to increase the stability of the measurement.
Measurement results On the Vibrometer page the measurement results are displayed on the screen, successfully combining the need for clarity and complete information. 2 3 4 1 5 7 6 8 Overall measurement: 1. channel that the measurement displayed refers to 2. status of the channel displayed: = enabled 3. 4. 5. 6. 7. 8.
Synchronous measurement: 2 3 4 1 5 7 6 8 1. channel that the measurement displayed refers to 2. status of the channel displayed: = enabled = disabled 3. sensor connected to the channel 4.
For correct measurement ensure that the shaft velocity is stable and is read correctly by the instrument. One of the following symbols will be displayed in the event that it is not read correctly, is unstable, or is lower than the minimum value or higher than the maximum one (see Appendix A): Symbol Condition Action to be taken - Check that the rotating body is not executing an acceleration ramp: otherwise wait till the end of the ramp .
− connect the photocell to the N300 instrument and position it at a distance of between 50 and 400 mm from the rotating body. Slowly turn the rotating body (if possible by hand, otherwise as slowly as possible) and check that the LED positioned on the back of the photocell only lights up once per turn, when the ray of light lights up the reference mark. If that is not the case, move the photocell closer to or further away from the piece or tilt it away from the surface.
2. 3. 4. 5. 6. saving date and time frequency field used number of averages global vibration value (Overall) of channel A, with units and measurements highest component of the vibration of Channel A, expressed for the purpose of brevity in the value @ frequency format 7. global vibration value (Overall) of channel B, with units and measurements 8.
Chapter 6 Balancing function One of the most frequent causes of vibration is an unbalanced rotating body (unevenness of the mass around its rotation axis), which can be corrected by balancing. The N300 instrument can be used to field balance any type of rotating body, on one or two planes, using 1 or 2 vibration detectors and a photocell. All of the situations are covered by ad hoc procedures guiding the operator step-by-step through the sequence of operations.
Warning: Take great care when positioning the photocell: as the rotating body requires manual intervention, make sure that it is still and cannot be started up accidentally. If the rotating body cannot be rotated by hand when positioning the photocell, it should be positioned in points in which the LED is visible without having to get too close to the moving bodies. Further information can be found in the appendix entitled Balancing precision for rigid rotating bodies.
Unbalance measurement and correction calculation. Selecting the symbol in the main screen opens the Balancing function: the value of the correction mass to be applied to plane P1 will be displayed based on the parameters of the last calibration carried out. In the case of two-plane balancing, press the key to display the correction mass on plane P2. This page contains the following information: 2 3 1 5 4 6 7 9 8 1.
plane to which the sensor must be applied, which must always remain connected to channel A of the N300 instrument. The correction displayed relates to the same plane on which the detector is applied. Warning: Two-plane balancing with a single sensor involves moving the same detector from one plane to another various times, but it must always be repositioned in the exact same position each time.
Additional functions By pressing the key, the additional functions bar displays the functions available in the unbalance measurement page of the balancing function: allows access to the calibration values for the current balancing (see 6 – 6 Calibration procedure). The guided procedure starts automatically at the first step yet to be carried out, or the last step (in the event that they have already been completed). opens the balancing records (see next paragraph).
Calibration procedure Calibration, required in order to assess the unbalance of a rotating body, is generally a procedure composed of various steps to be performed in sequence: - Calibration for single-plane balancing: 1) first spin without test mass 2) second spin with test mass on the balancing plane - Calibration for two-plane balancing with two sensors: 1) first spin without test mass 2) second spin with test mass only on the P1 balancing plane 3) third spin with test mass only on the P2 balancing plane
8. 9. 10. 11. average velocity of the rotating body at the selected calibration step velocity unit of measurement value and angular position of the calibration mass plane on which to apply the test mass test mass on plane P1 test mass on plane P2 12.
2. Sensor type The same explanations described in 5.2 – Sensor type apply. 3. Synchronous filter width The same explanations described in 5.4 – Synchronous filter width apply. 4. Units of measurement The same explanations described in 5.2 – Units of measurement apply. 5. Type of vibration The same explanations described in 5.2 – Type of vibration apply. 6. Units of frequency The same explanations described in 5.3 – Units of frequency apply. 7.
Note: The test mass value must be indicated in generic U units: the operator is free to decide whether to convert these U into the physical units preferred (mg, g, kg, etc), bearing in mind that the unbalance and required correction values will also be expressed in the same U units. Warning: The test mass has been chosen correctly if it causes the vibration to vary enough in each of the spins, compared to that of the first spin.
Chapter 7 CEMB N-Pro program (optional) Data saved in the N100 and N300 instruments can easily be imported into a PC, organised and saved to the hard disk and subsequently analysed, compared, printed, etc. These operations are made possible thanks to CEMB N-Pro software (Professional Environment for N-Instruments), available for Microsoft Windows operating systems. The interface has been carefully designed to make it intuitive and therefore extremely simple to use even for inexperienced users.
Note: In the event of installation in a Windows Vista and Windows 7 operating system, the following operations must be completed before the software can be used: - right-click on the CEMB N-Pro program icon on the desktop - select the 'Compatibility' menu - enable the option 'Execute program in operating mode for:' and choose 'Windows XP (Service Pack 2)' - enable the option 'Execute program as administrator' - press OK Installation of drivers for USB communication with the N100 and N300 instruments Do no
Enable the options ‘Search for the best driver in these paths’ and ‘Include this path in the search’. Using the ‘Search’ button, select the ‘USB driver’ sub-folder from the one in which the CEMB N-Pro software is installed. At this point press ‘Next >’. At the end of this guided procedure, the ‘USB Serial Converter’ hardware should be correctly installed.
Activating the software The first time the software is started a pop-up is displayed containing the software’s serial number (S/N) and requesting the corresponding activation code. This can be obtained by sending an e-mail to CEMB customer service Vibration Analysis division (see www.cemb.com) specifying the subject: "CEMB N-Pro activation code" and specifying in the message your data and the serial number (S/N) as shown in the pop-up.
Use of the software The buttons on the function bar in the upper part of the page allow full access to all of the functions available in the CEMB N-Pro software. The data record contents are always visible on the left, subdivided into vibration measurements (overall, or synchronous) balancing operations - All of the remaining space is reserved for information related to the function enabled at that moment in time, as described in the following paragraphs.
- - record viewing functions: - display the element selected - edit the notes associated with the element displayed (vibration or balancing measurement). For maximum flexibility, 3 different notes can be associated to each element: users are free to enter the information deemed appropriate on a case by case basis.
- connect the N instrument to the PC and wait for a few seconds - click on the drop-down menu again and select Refresh - the port that the instrument has been connected to is the one added to the list noted down previously Warning: Always connect the N instrument to the same USB port on the PC. Otherwise it will be necessary to change the COM port number in the General Settings window, and in some cases even repeat the USB driver installation procedure.
Note: Pressing before the transfer is complete quits this operation immediately, therefore preventing its completion. Note: Reading data from the instrument does not change the records present in the instrument itself: after checking that they have been imported into the PC correctly, the operator can delete them from the instrument if he wishes, as described in 2 – 4 Measurement records. Note: Balancing data is only available for the N300 instrument.
Displaying data present in the records After selecting a file from the records, the contents can be displayed in a clear and detailed manner by pressing the key. The various data types will be displayed as follows: Overall vibration value measurement: 2 3 5 1 4 6 1. 2. 3. 4. 5. 6.
- (zoom x) : the portion of the x axis to be enlarged can be selected by clicking on one point and moving the cursor horizontally; - (zoom y) : the portion of the y axis to be enlarged can be selected by clicking on one point and moving the cursor vertically; - (autoscale) : by clicking on the graph the extremes of the axes will automatically be set to the most suitable values, based on that displayed; - (zoom in) : clicking in one point enlarges the zone around it; - (zoom out) : clicking in one p
Synchronous vibration value measurement: 1 2 4 3 5 1. 2. 3. 4. 5. amplitude of the synchronous vibration value phase of the synchronous vibration value frequency of the synchronous vibration value measurement information and parameters notes associated with the measurements Balancing data: 1 2 4 3 5 7 8 6 1. type of balancing (on one or two planes) 2. value (in generic U units) and phase of the initial imbalance 3.
4. value (in generic U units) and phase of the final imbalance (that is to say after balancing) 5. value and phase of the final vibration (that is to say after balancing) 6. velocity of the rotating part 7. balancing information and parameters 8. notes associated with balancing The notes associated with each measurement can be entered or edited at any time by pressing .
Note: To assist users, the CEMB N-Pro program includes some example templates that can be used as a base to create customised reports. These models are located in the sub-folder named Report Templates in the N-Pro directory in which the program is installed. Warning: If you wish to customise one of the templates present in the Report Templates folder, it is best to save the edited model with another name or in a different folder.
Appendix A N300 instrument technical data - Instrument - Dimensions (W x L x H): 84 x 180 x 52.5 mm - Weight: 385g including battery - Operating conditions - Temperature: from -10° to +50° C - Air humidity: from 0 to 95% without condensate - Power supply - rechargeable 1.8Ah Lithium battery - charging time: less than 5 hours (when battery is completely flat) - battery charger: - input 100-240 VAC, 50/60 Hz, 0.2A - output 8.4VDC, 0.71A, 6.
A- 2 Technical data
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 Information related to the creation of customised templates (models) for certificates generated by CEMB N-Pro software. Numeric codes When the certificate is created, the CEMB N-Pro software automatically replaces some of the default codes in the template (#x# format) with corresponding information related to the measurements displayed at the time.
D-2 #49# N100 or N300 apparatus firmware version #50# Frequency and velocity units of measurement #51# Date on which the measurement was taken #61# Time at which the measurement was taken #301# Total vibration value (overall) - channel A #302# Total vibration value (overall) - channel B #311# Synchronous vibration value - channel A #312# Synchronous vibration value - channel B #321# Synchronous vibration phase - channel A #322# Synchronous vibration phase - channel B #331# Synchronous
#477# Vibration peak 2 value – channel B #...
processing program is used and the document is then saved in HTML format, the alignment, spacing, sizes, etc may be altered after being converted and saved and the final HTML model may not turn out exactly as desired. Users of Microsoft Word 2000 or higher will have experienced this situation frequently. Various HTML editors are available, including: - KompoZer multilingual, it can be downloaded free of charge from the website http://www.kompozer.
Appendix E List of symbols used for the instrument Functions accessed from the main screen vibration measurement (vibrometer) balancing instrument’s operating parameter settings Functions accessed from the additional functions bar open the recorded measurements page display a list of the highest vibration peaks present open the calibration procedure (self-learning) for the current balancing operation open the calibration procedure (self-learning) for a new balancing operation value of test mass used in th
Operating parameters accelerometer 1, or accelerometer type 1 (in the event that there are two different types) accelerometer 2, or accelerometer type 2 (in the event that there are two different types) velocimeter 1, or velocimeter type 1 (in the event that there are two different types) velocimeter 2, or velocimeter type 2 (in the event that there are two different types) current date current time unit of measurement to be used for physical sizes display backlighting intensity time after which the display
vibration expressed in mm/s vibration expressed in µm (1 µm = 10-6 m) vibration expressed in inch/s (1 inch/s = 25.4 mm/s) vibration expressed in mils (1 mil = 25.
Specific symbols used for data loaded from the records vibration measurement records balancing records display the measurement saved in position 3 of the records overall vibration value amplitude of the vibration’s highest component frequency of the vibration’s highest component unbalance of the rotating body initial unbalance of the rotating body (first calibration spin) and residual unbalance (end of balancing) Operator messages press OK to start the measurement press OK to confirm data overwriting or an
23826 MANDELLO DEL LARIO (LC) ITALY BALANCING ACCURACY OF RIGID ROTORS The purpose of balancing is to improve the distribution of the mass of a rotor so that it may rotate on its bearings without creating unbalance centrifugal forces higher than a predetermined permissible value. This aim can and must be attained only to a certain degree as, even after balancing, residual unbalance will inevitably persist.
BALANCE QUALITY GRADES FOR VARIOUS GROUPS OF ROTORS Note: The rotor classes in italics are not included in the ISO standards, but have been added by the Author.
HOW TO USE THE BALANCING TOLERANCE GRAPH The balancing quality grade G is determined according to the characteristics of the rotor and the machine on which the rotor is mounted under normal service conditions (see table). The balancing tolerance in gr·mm may be obtained from the residual eccentricity e (micrometers) multiplied by the rotor weight P (kg). The residual permissible eccentricity may then be deduced from the graph, as a function of the rotational speed, in correspondence with the G grade.
CONDITIONS OF VALIDITY OF THE BALANCING TOLERANCE GRAPH 1.
P in grams d in mm h1-h2-h in mm The total weight to be removed from a drill hole is: P = 7.85 10-3 V (where V is the total volume of the hole) (1) considering that: V = V1 + V2 where 2 æd ö V1 = π ⋅ ç ÷ ⋅ h1 (Volume of cylindrical pan) and è2ø V2 = 2 1 æd ö π ⋅ ç ÷ ⋅ h2 (Volume of conical part) 3 è2ø h1 = h − h2 ; h2 = d tan 30° 2 (1) becomes: 3) If b < æπ ö P = 7.85 ⋅ 10 −3 ç d 2 h − 0.
Weight removed in grammes (For small weight see diagrams 2 – 3 – 4 – 5) Cone only 1 - GENERAL DIAGRAM OF WEIGHT REMOVABLE BY DRILLING IN STEEL Hole depth (h) in mm
Ø 0,5 – 1,5 mm Weight of material removed (steel) in milligrammes Cone only 2 - DIAGRAM FOR FINE DRILLING Hole depth (h) in mm
Ø 1 – 6 mm Weight of material removed (steel) in grammes Cone only 3 - DIAGRAM FOR FINE DRILLING Hole depth (h) in mm
Ø 2 – 10 mm Weight of material removed (steel) in grammes Cone only 4 - DIAGRAM FOR FINE DRILLING Hole depth (h) in mm
Ø 5 – 12 mm Weight of material removed (steel) in grammes Cone only 5 - DIAGRAM FOR FINE DRILLING Hole depth (h) in mm
6 - DIAGRAM OF WEIGHT per cm OF A STEEL PLATE AS A FUNCTION OF DIMENSIONS L - s Weight of plate in g/cm Width of plate (L) in mm Thickness of plate (s) in mm
