CEMB USA N300 User Manual

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Portable equipment

N300

Vibrometer Balancer

USER INSTRUCTION

Dichiarazione CE di Conformità

Declaration of Conformity

EG-Konformitäts-Erklärung

Déclaration de Conformité

Declaration de Conformidad CE

Declaração CE de Conformidade

EC-Verklaring van Overeenstemming

Försäkran om CE-överensstämmelse

CE-overensstemmelses-erklæring

CE-vaatimusmukaisuus-vakuutus

∆ήλωση Συµµόρφωσης CE

La Ditta

The Company

Die Firma

La Maison

La Compañia

A Empresa

dichiara con la presente la conformità del Prodotto

herewith declares conformity of the Products

erklärt hiermit die Konformität desProdukts

déclare par la présente la conformité du Produit

Declare la conformidad del Producto

com a presente declara a conformidade do Produto

Costruzioni Elettro Meccaniche ing. Buzzi & C. S.p.a.

23826 MANDELLO DEL LARIO - (Lecco) ITALY

Strumento Instrument Instrument Instrument

Instrumento Instrumento

Tipo

Type

Typ

Type

Tipo

Nr. di serie

Serial Number

Fabriknummer, usw

Numero de série

Numero de fabricacion

Número de série

Numero Distinta Base

Manufacturing List Number

Erstellungsliste nummer

Numéro de liste de construction

Numero lista de base

Número da Lista de Base

Via Risorgimento, 9

N300

--------------------

48AN64013

Het bedrijf

Företag

Virksomheden

Virksom

heten

Yhtiö

Η εταιρία

verklaart bij deze de onvereenstemming van het product

∆ηλώνει µε την παρούσα τη συµβατότητα του Προϊόντος

försäkrar härmed att produkten

erklærer herved, at produktet

bekrefter herved at produktet

vakuttaa että tuote

Instrument Instrument Instrument Instrument Instrument

Όργανο

Type

Typ

Type

Tyyppi

Τύπος

Serienummer

Serienr

Sarjanro

Αρ. Σειράς

Nummer basislijst

Produktionslistans nr.

Produktionslistens nr.

Produksjonslistens nr.

Valmistusluettelon nro.

Αριθµός Καταλόγου Παραγωγής

alle norme sottostanti / with applicable regulations below / mit folgenden einschlägigen Bestimmungen / selon les normes ci-dessous / con directivas subaplicables / com

as normas indicadas em baixo / met de onderstaande normen / överensstämmer med följande föreskrifter / stemmer overens med følgende forskrifter

on yhdenmukainen seuraavissa laeissa olevien ehtojen kanssa / στους παρακάτω κανονισµούς

Direttive CEE / EC Directive / EG Richtlinie / Directive CEE / Directivas CE / Directivas CEE / EEG-richtlijnen

EU-direktiv / EØF-direktiver / EU-direktiver / EU-direktiivit / Οδηγίες CEE

2006/95/CE – 2004/108/CE

Norme Armonizzate Adottate /Applied Armonized Standards / Angewendete Harmonisierte Normen / Normes Harmonisées Appliquées / Normas Aplicadas en

Conformidad / Normas Harmonizadas Aplicadas / Toegepaste geharmoniseerde richtlijnen / Standarder / Standardit / Εναρµονισµένοι Εφαρµοζόµενοι Κανονισµοί

EN 12100-1:2005 EN 12100-2:2005 EN 294:1993 EN 349:1993 EN 418:1992 EN 457 :1993 EN 60204-1:2006 X EN 60439-1:1990 X EN 61000-6-3/A11:2005 X EN 61000-6-1/IS1:2006 X EN 61000-6-4-:2002 X EN 61000-6-2:2006 X

Data / Date / Datum / Date / Fecha / Data

Datum / Datum / Dato / Pvm / Ηµεροµηνία

16/03/2009

CEMB Spa

Ing. Carlo Buzzi

Firma /Signature / Unterschrift /Signature / Firma / Assinatura

Handtekening / Underskrift / Allekirjoitus / Υπογραφή

M06PRG01

N300 rev. 1.2 Table of contents

Chapter 1

- General description

¾ Standard accessories ……………………………… 1 - 1 ¾ Optional accessories ……………………………… 1 - 2 ¾ Inputs ……………………………….……… 1 - 2 ¾ Reset button ……………………………………… 1 - 3 ¾ Battery ……………………………………………… 1 - 4 ¾ Adjustment and calibration…………………………. ..… 1 - 5 ¾ General advice ……………………………………… 1 - 5

Chapter 2 -

Chapter 3 -

Chapter 4

- Setup function

General overview

¾ Keypad ……………………………………………... 2 - 1 ¾ Start / Stop acquisition functions ……………………… 2 - 3 ¾ Changing the channel displayed ………………….…... 2 - 3

¾ Specific additional functions for the various pages…….... 2 - 3

Initial screen (menu)

¾ Sensor sensitivity ……………………………….……. 4 - 1 ¾ Date ……………………………………….……. 4 - 2 ¾ Time ………………………………………….…. 4 - 3 ¾ Units of measurement system …………….…….…. 4 - 3 ¾ Display brightness ……………………….……..…...…. 4 - 3 ¾ Backlighting auto-off time …………………………..…. 4 - 3 ¾ Instrument auto-off time ………………………..……. 4 - 3

Chapter 5

- Vibrometer function

¾ Measurement setting ………………………….…. 5 - 1 ¾ Settings only valid for Overall measurements ……... 5 - 3 ¾ Settings only valid for synchronous measurements….…. 5 - 4 ¾ Measurement results ………………………….….. 5 - 5 ¾ Additional functions ………………………….….. 5 - 8

Table of contents 1

Chapter 6

- Balancing function

¾ Imbalance measurement and correction calculation.……….. 6 - 3 ¾ Additional functions ………………………………… 6 - 5 ¾ Displaying balancing results from the records ……….… 6 - 5 ¾ Measurement settings ………………………………… 6 - 7

Chapter 7 -

CEMB N-Pro program (optional)

¾ System requirements …………………………….… 7 - 1 ¾ Installation of the software ………………………. 7 - 1 ¾ Installation of drivers for USB communication

with N100 and N300 instruments ……………………… 7 - 2

¾ Activating the software ……………………………… 7 - 4 ¾ Use of the software …………………………..….. 7 - 5 ¾ Function bar ……………….………………….…. . 7 - 5 ¾ General settings ………………….…………………... 7 - 6 ¾ Reading data from the N100 or N300 instrument ………. 7 - 7 ¾ Data records imported from the N100 or N300 instrument 7 - 8 ¾ Displaying data present in the records ………………. 7 - 9 ¾ Generation and printing of certificates (reports) ……..… 7 – 12 ¾ Generation and printing multiple

measurement certificates (multi-report) ………………..... 7 - 13

Appendix A

- Technical data

Appendix B -

Appendix C

Appendix D

Appendix E -

Attachment:

- Guide to interpreting a spectrum

- Information related to the creation of customised Templates

List of symbols used for the instrument

Balancing precision for rigid rotating bodies

Judgement criteria

(models) for certificates generated by the CEMB N-Pro program.

Table of contents

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.

Standard accessories:

- N300 instrument complete with battery

-battery charger

- 1 TA-18S accelerometer transducer

- 1 transducer connection cable

- 1 magnetic base

- 1 probe

- 18,000 RPM photocell complete with upright and magnetic base

- roll of reflecting tape

- graduated disc for angular measurements

- multilingual manual on CD-ROM

- heavy duty, high resistance, water and air-tight carrying case.

- “Getting started” leaflet with basic instructions for use

General description 1 - 1

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.

Inputs

12 3 456

1 – channel A sensor input 2 – channel B sensor input 3 – photocell input for velocity measurement 4 – type B mini USB port for connection to PC 5 – instrument reset button 6 – battery charger connector

The sensors and photocell can be connected by simply inserting the connector into the relative socket, pushing it in until a "click" is heard; make sure that the safety connection is aligned correctly, as shown in the illustration.

1 - 2 General description

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

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. It is purposely located in a difficult to access area to prevent it from being reset unintentionally.

button

Warning:

In the event of an error that cannot be reset automatically, the message "Err" will be displayed on the screen followed by the number identifying the error that occurred. Should this situation occur, the instrument must be reset manually by pressing the reset button.

Warning:

Do not use pointed objects such as needles, punches or suchlike to press the reset button as they could damage it.

General description 1 - 3

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. one hour)

- battery flat: recharge within 5 minutes

If the battery is flat and the instrument is not recharged within 5 minutes it will switch off. This would interrupt any active measurements not yet saved.

When the battery charger is connected the display lights up briefly indicating the connection, even when the instrument is switched off. The battery icon remains animated when the instrument is recharging, progressively filling up. When charged, the animation stops and the ‘battery fully charged’ icon is shown.

Warning

When connecting the battery charger, first insert the connector into the relevant socket on the N300 instrument; only plug it into the power supply socket when this has been done. When recharged, unplug the battery charger from the power supply socket before removing the connector from the instrument.

Warning:

We strongly recommend recharging the instrument when switched off; as charging takes less than five hours, avoid leaving the battery connected for an excessively long period of time (maximum 12 hours).

Warning:

The lithium battery withstands frequent charging-discharging cycles easily, even on a daily basis, however allowing it to run out completely can damage it. For this reason we recommend it is charged at least once every three months, even when not used for long periods of time.

Note:

As the display backlighting consumes the most power, it switches off automatically after a certain period of time (settable) has passed without pressing any key. Pressing any key (excluding ) will reactivate it.

1 - 4 General description

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. Alternatively, the battery can be disconnected before storing the instrument for long periods of time: remember that in this case the date and time will need resetting the next time the instrument is used. In the case of the second hypothesis, to maximise the battery life it should be fully charged at least every 8-9 months.

Adjustment and calibration

Before delivering the N300 instrument to the client, CEMB laboratories subject it to a complete adjustment, calibration and test procedure to guarantee it works correctly.

General advice

Store and use the instrument away from sources of heat and considerably strong electromagnetic fields (high-power inverters and electric motors).

Measurement precision can be invalidated by the connection cable between the transducer and the instrument, therefore we recommend that:

- the cable does not share the same path as the power cables;

- any power cables crossed should be overlapped perpendicularly;

- the shortest possible cable should be used; in fact floating lines act as active and

passive aerials.

Warning:

Always pay the utmost attention during measurement operations, using suitable protective devices when possible to safeguard the operator from moving parts When not possible, always leave an adequate safety distance between them.

General description 1 - 5

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. In the event of any problems, take note of this data before contacting CEMB customer service to enable us to provide you with a better service.

- OK key

In the main screen it confirms the selection made and opens the corresponding page. In the Setup screen it confirms the value of the parameter selected. In the Vibrometer and Balancing screens it performs different functions:

- it confirms values when setting acquisition parameters

- it stops or starts the measuring process (see 2-3 Start/stop acquisition

function).

- when the additional functions bar is visible it is used to select the desired

function In the records screen it opens the desired function from the additional functions bar.

General overview 2 - 1

- 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.

- change channel key (A/B)

In the measurement screens, it changes the channel displayed.

- directional arrows

They change the element selected, recognizable because displayed in negative (white on a black background), or they change the value of that which is being set.

2 - 2 General overview

Start/Stop acquisition function

In all measurement screens acquisition is started by pressing and is later stopped by

pressing the same .

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.

In the first few moments after the start of every measurement, the N300 instrument can automatically determine the most suitable amplification based on the signal received from the sensors. If the vibration is higher than the instrument's limits of operation (see Appendix A), the channel saturation symbol will be displayed.

Changing the channel displayed

To ensure maximum clarity in the presentation of data, the N300 instrument always displays one channel at a time, indicated respectively by the symbol or

In the event that both measurement channels are to be used for the measurement, the channel displayed can be changed by pressing the key.

Specific additional functions for the various pages

The specific additional functions available in each page can be displayed by pressing the

key. A bar will appear in the lower part of the screen, from which the desired

function can be selected using the and arrows, and confirmed by pressing the

key .

Press to quit the bar without selecting anything.

General overview 2 - 3

- 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 key to switch between displaying channel A peaks and channel B peaks.

Press the key to exit this page and return to the vibrometer screen.

- Measurement records

With the N300 instrument, measurements taken or balancing operations performed can easily be saved in two different records:

- vibration measurement records (24 positions) symbol

- balancing data records (10 positions) symbol

The size of the vibration measurement records is optimised to contain all of the measurements for a typical real situation: detection in the three orthogonal directions on four supports, before and after maintenance work on machinery composed of two elements (motor and pump, or motor and fan).

In the Vibrometer and Balancing screens, press and then select the symbol in the additional functions bar to open the corresponding records page.

The symbol in the upper part identifies the current record, in which every position is marked with the symbol and a sequential number; empty positions are marked by the symbol -----, the others contain the date and time that their contents were saved, shown as DD/MM/YY HH:mm, where:

- DD is the day of the month (from 1 to 31)

- MM is the month of the year (from 1 to 12)

2 - 4 General overview

- 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. In the case of two-channel acquisition, data is automatically saved in the

same position of the record for both channels.

Note:

If the position selected is already in use, before saving the data the symbol asks the operator to confirm that the data should be overwritten. Press to confirm; the key interrupts the saving procedure and another position can be selected.

- load the measurements (or balancing operation) selected

Loading data from the records allows the user to view results saved

previously in a relevant screen, described respectively in

5-8 Displaying measurements from the records and 6-5 Displaying balancing results from the records.

- delete the measurement selected, emptying the relative position in the

records.

- delete all of the measurements, emptying the records completely.

General overview 2 - 5

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.

2 - 6 General overview

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. Vibrometer

- measurement of the total vibration value (Overall), together with the amplitude and

frequency of the highest component (main peak value)

- measurement of the vibration modulus and phase at the synchronous frequency at

the velocity of the rotating body or its multiples (1xRPM, 2xRPM, 3xRPM, 4xRPM and 5xRPM)

2. Balancing

- field balancing of rotating bodies with one or two correction planes

3. Setup

- setting of the degree of sensitivity of sensors connected to the instrument

- setting the instrument’s general operating parameters

Initial screen 3 - 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.

3 - 2 Initial screen

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 key, insert the desired value when requested to do so, then confirm with the key.

To quit the edit function without changing the previous value press .

Sensor sensitivity

The N300 instrument can be used with various types and models of sensors, and therefore for correct measurements you must set the exact degree of sensitivity (= number of volts per unit) of those effectively connected. Press the key to vary the sensitivity of the sensor selected, varying one figure at a time.

The and arrows increase or decrease the figure selected (displayed in negative) by one unit.

By pressing and , the figure on the left or on the right can be selected respectively.

Setup function 4 - 1

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 ACC

- velocimeter VEL

- displacement DIS

two different sensitivity levels can be set, identified respectively by “1” and “2”. Therefore six different sensors can be defined:

- ACC-1 accelerometer 1 (powered – IEPE type)

- ACC-2 accelerometer 2 (powered – IEPE type)

- VEL-1 velocimeter 1(not powered)

- VEL-2 velocimeter 2(not powered)

- DIS-1 displacement sensor 1 (not powered)

- DIS-2 displacement sensor 2 (not powered)

making it possible to use the same types of sensors but with different sensitivity levels.

Typical sensitivity values for the various sensors are:

SENSOR TYPE SENSITIVITY TYPICAL VALUE

Accelerometer (ACC) mV/g 100

Velocimeter (VEL) mV/(mm/s) 21,2

Displacement (DIS) mV/µm 8

Warning:

The sensitivity of some models may differ from the typical values shown; make sure that the sensor is set with the correct value taken from its documentation.

Date

The date must be entered in the N300 instrument using two figures for the day, two for the month and two for the year, in this order. To assist the operator, the dd/mm/yy format is displayed below the current date. New values can be entered following the same procedure as that described above for the sensitivity of the sensors (see above).

4 - 2

Setup function

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).

Units of measurement system

The units of measurement used for acceleration, velocity and movement values can be respectively:

- g; mm/s; µm : metric units

- g; inch/s; mils : imperial units

After pressing the key, you can scroll through all of the possibilities using the and arrows.

Display brightness

The brightness of the display can be adjusted to provide excellent visibility in various environmental conditions, from minimum (no backlighting) to maximum. This is possible using the and arrows after having enabled the “enter values”

mode by pressing .

Backlighting auto-off time

To extend the duration of the battery before it needs recharging, the display backlighting turns off automatically after a preset amount of time (settable from 1 to 255 seconds) has passed since the last key was pressed. Pressing any key reactivates the backlighting.

Instrument auto-off time

To extend the duration of the battery before it needs recharging, the instrument turns off automatically after a preset amount of time (settable from 5 to 60 minutes) has passed since the last key was pressed. To use the instrument again, turn it on by pressing

Setup function 4 - 3

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). In some cases it may be interesting to know the synchronous vibration modulus and phase values, that is to say corresponding to the rotating body’s rotation velocity (1xRPM), or its multiples (2xRPM, 3xRPM, 4xRPM, 5xRPM). The vibrometer function can be used to take this type of measurement easily and intuitively, saving the results in a special record.

Measurement settings

The settings used to measure vibration are all displayed in the Vibrometer page and can be adjusted by pressing the key: for greater clarity all measurement results are hidden, with only adjustable parameters remaining visible. Before changing the settings make sure that the channel displayed in the upper left hand corner is the one that you wish to change;

otherwise change it using the key .

The parameter that can be changed is displayed in negative, by pressing the and the

arrows you can scroll through all of the values that can be selected. With the

and keys, you can move to the previous or next parameter.

These can be divided into two categories:

− specific, only valid for the channel displayed at that time

− common, which automatically apply to both: this group includes anything concerning

the type of measurement required

Vibrometer function 5 - 1

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 4.1 – Sensor sensitivity):

− ACC-1 : type 1 accelerometer (powered – IEPE type)

− ACC-2 : type 2 accelerometer (powered – IEPE type)

− VEL-1 : type 1 velocimeter (not powered)

− VEL-2 : type 2 velocimeter (not powered)

− DIS-1 : type 1 displacement sensor (not powered)

− DIS-2 : type 2 displacement sensor (not powered)

When required, the N300 instrument automatically supplies power to the sensors connected.

Warning:

To obtain a sufficiently accurate measurement the sensor effectively connected must be correctly associated with each channel.

3. Measurement:

Indicates the type of measurement carried out:

− Overall: overall vibration value

− Synchronous measurement: value of the synchronous component at the rotation

velocity (1xRPM) or its multiples (2xRPM, 3xRPM, 4xRPM, 5xRPM)

4. Units of measurement

Select the unit of measurement in which the vibration is to be expressed: the possibilities are:

− acceleration (g)

− velocity (mm/s or inch/s)

− movement (µm or mils)

Warning:

Displacement and speed measurements can be taken when displacement sensors are used, however their use means acceleration measurements cannot be taken.

5 - 2

Vibrometer function

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. It is

a direct indication of the vibration’s “energy” content: in practice it represents the power brought with the vibration and discharged onto the supports or bases of the vibrating structure.

− PK (Peak): peak value

the maximum value reached by the vibration in a certain period of time.

− PP (Peak-to-Peak): peak-to-peak value

the difference between the maximum value and the minimum value reached by the

vibration in a certain period of time;

normally used for movement measurements.

6. Units of frequency

Indicates how to display the velocity and frequencies, and can be chosen from:

- Hz – cycles (revs) per second

− RPM – revs per minute

Note:

The relation 1 Hz = 60 RPM clearly exists between the two units

Settings only valid for overall measurements

1. Frequency range:

The overall vibration value usually originates from the sum of various contributions, caused by various phenomena, which are therefore associated with different frequencies. Depending on the situation, you may only wish to consider those corresponding to a certain range of frequencies in overall measurement:

− 1-100 Hz if the interest is limited to phenomena with low frequencies

− 2-200 Hz if the interest is limited to phenomena with relatively low frequencies

− 5-500 Hz if the phenomenon also involves average frequencies

− 10-1000 Hz to comply with the conditions set forth in the ISO 10816-1 standard

(typical)

Note:

A commonly used practical consideration is to check that the maximum frequency is set to at least 20-30 times that of the rotation of the shaft examined. This means

Vibrometer function 5 - 3

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. All values between 1 and 16 are acceptable, but 4 averages are more than enough for normal vibration measurements on rotating machines.

Settings for synchronous measurements only

1. Synchronous filter width:

This parameter, identified for historical reasons as the synchronous filter width, is displayed next to the symbol and is measured as a percentage. It indicates the resolution in frequency of the synchronous analysis, or rather the instrument’s ability to separate contributions from the various frequencies. Values from 1% to 100% are available. For example, a value of 5% indicates that the contribution of all of the frequencies of the 1xRPM±5% band (which cannot be distinguished from each other) is included in the calculation of the synchronous value. Smaller values (or rather, narrower filters) produce more accurate measurements, but require considerably longer acquisition times. For example, with a 1% filter and particularly slow rotating bodies (60 RPM) you must wait for a few minutes before completing a measurement. To set this parameter you need to find the right balance between accuracy and time.

After setting the desired values, press to confirm them; or press the key to quit the settings without changing the existing ones.

5 - 4

Vibrometer function

Measurement results

On the Vibrometer page the measurement results are displayed on the screen, successfully combining the need for clarity and complete information.

Overall

1. channel that the measurement displayed refers to

2. status of the channel displayed:

= enabled

measurement:

2 3 4

= disabled

3. sensor connected to the channel

4. measurement taken (Overall)

5. number of averages

6. frequency band

7. vibration value, with unit and type

8. amplitude and frequency of the vibration’s highest component. The more

components the vibration is composed of, the more the overall measurement will be greater than the amplitude of the dominating component. If the two values are very similar, the vibration takes on an almost sinusoidal form.

The measurement can be started and stopped by pressing .

Note:

Values obtained this way can be used to assess the state of operation of the instrument, using, for example, the tables and diagrams present in Appendix B of this manual.

Vibrometer function 5 - 5

Synchronous measurement:

2 3 4

1. channel that the measurement displayed refers to

2. status of the channel displayed:

= enabled = disabled

3. sensor connected to the channel

4. order of the harmonic measured

1xRPM = fundamental harmonic (synchronous with the rotation velocity) 2xRPM = second harmonic (frequency double the rotation velocity) 3xRPM = third harmonic (frequency triple the rotation velocity) 4xRPM = fourth harmonic (frequency four times the rotation velocity) 5xRPM = fifth harmonic (frequency five times the rotation velocity)

5. filter width

6. vibration modulus, with unit and type

7. vibration phase expressed in degrees (0°÷359°)

8. frequency of the harmonic measured; it coincides with the rotation velocity in the

event of a 1xRPM measurement, otherwise it is respectively double, triple, etc.

The measurement can be started and stopped by pressing

5 - 6

Vibrometer function

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

velocity value not stable

over time.

velocity signal absent, or of

a value below the

minimum acceptable data

for the instrument

velocity greater than the

maximum acceptable value

for the instrument

Note:

Remember that in order to take a synchronous measurement you must connect the photocell and check that it is positioned correctly, following these instructions:

- apply a suitable reflecting sticker (or tag) on the rotating body as a point of

reference (0°). Starting from this position, the corners are measured in the opposite direction compared to that of the shaft’s rotation.

wait till the end of the ramp .

- Check that the velocity of the rotating body does not oscillate periodically: otherwise take any steps possible to stabilise it.

- Check that the photocell and reflecting

sticker are positioned correctly.

- Check that the photocell is NOT

positioned in a point with excessively high vibration, which would prevent the light from being reflected off the reflecting sticker.

- Check that the velocity of the rotating body is above the minimum value: otherwise it must be increased.

- Check that the photocell and reflecting sticker are positioned correctly (if they produce more than one impulse per turn they generate a false high speed)

- If the velocity of the rotating body is effectively higher than the maximum acceptable value it must be reduced

Vibrometer function 5 - 7

− 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.

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.

Additional functions

Pressing the key, the additional functions bar shows those available in the Vibrometer page:

access to the vibration measurement records (see next paragraph).

Displaying measurements from the records

Vibration measurements loaded from the records are displayed in a special screen laid out as follows:

Overall

vibration measurement:

1 2

1. position number in the measurement record

5 - 8

7 8

Vibrometer function

2. saving date and time

3. frequency field used

4. number of averages

5. global vibration value (Overall) of channel A, with units and measurements

6. 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. highest component of the vibration of Channel B, expressed for the purpose of

brevity in the value @ frequency format

- Synchronous vibration measurement

1 2

1. position number in the measurement record

2. saving date and time

3. order K of the measured harmonic (compared to the rotation velocity)

4. synchronous filter width

5. amplitude of the vibration of channel A with units and measurements

6. vibration phase - channel A

7. amplitude of the vibration of channel B with units and measurements

8. vibration phase - channel B

9. frequency of the measured harmonic (equal to K times the rotation velocity).

8 9

Vibrometer function 5 - 9

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.

In practice, the most frequent goal is to reduce vibration to an acceptable goal below a certain value (see Appendix B). However reducing the unbalance only has an effect on the synchronous component 1xRPM. If this component has a low value, accompanied by a high Overall value, it indicates problems not connected with unbalance and that cannot therefore be corrected by balancing (see Appendix C). A preliminary analysis must therefore be carried out to assess the entity and cause of vibration before proceeding with balancing: the N300’s vibrometer function can be used to take an overall vibration measurement (Overall) and a synchronous value measurement 1xRPM (see chapter 5 –Vibrometer Function). Only proceed with balancing if the latter is predominant; otherwise it is best to concentrate on resolving other problems with the machine.

The following instructions must be complied with for correct balancing:

- position the sensors as close as possible to the supports of the rotating body to be balanced, using the magnetic base or fixing it with a threaded hole for good repeatability;

- apply a suitable reflecting sticker on the rotating body as a point of reference (0°). Starting from this position, the corners are measured in the opposite direction compared to that of the shaft’s rotation.

− connect the photocell to the N300 instrument and position it at a distance of

Balancing function 6 - 1

Warning:

Further information can be found in the appendix entitled Balancing precision for rigid

rotating bodies.

The balancing procedure is composed of two parts:

− calibration: a series of spins are used to determine the parameters required to balance

a determined rotating body;

− unbalance measurement and calculation of the correction.

Although calibration may be a laborious process, it is essential for it to be carried out correctly to avoid introducing errors in the subsequent calculation of the correction masses. The instrument automatically records the data and parameters from the last balancing operation carried out, proposing them to the operator the next time the calibration page is opened, even when the instrument has been turned off and on again.

Warning:

To use the calibration parameters from the previous balancing operation, the transducers must be placed in exactly the same position on the rotating body. This is relatively simple when using threaded holes, but can be more difficult with magnetic bases. Remember that a small difference, even of just a few millimetres, could make the previous calibration unsuitable.

For greater accuracy we recommend that the instrument is fully calibrated before every new balancing operation.

6 - 2 Balancing function

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. channel that the correction displayed refers to (by convention the channel A sensor is

considered applicable to plane P1, and that of channel B to plane P2)

2. status of the channel displayed:

= enabled

= disabled

3. sensor connected to the channel

4. correction for addition of mass

5. synchronous filter width

6. value of the correction mass expressed in generic U units: the correspondence

between U and real units of mass (mg, g, kg, …) is determined during calibration (see 6 – 6 Calibration procedure).

7. angular position in which to apply the correction mass to the rotating body (from 0°

to 359°)

8. velocity of the rotating body measured, from which the correction mass has been

calculated

9. type of balancing operation:

- single plane (with 1 sensor)

- on 2 planes with 2 sensors

- on 2 planes with 1 sensor, applied to P1

- on 2 planes with 1 sensor, applied to P2

In the case of two-plane balancing with a single sensor, the unbalance can only be calculated after vibration has been measured on both planes. To do this, measurement spins must be performed in pairs, positioning the detector alternately on the two planes. An indication of the type of plane to be used each time is shown by the symbol “type of balancing” as explained above. In this condition, pressing the key changes the

Balancing function 6 - 3

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:

detector from one plane to another various times, but it must always be repositioned in the exact same position each time. For this reason the use of threaded holes is strongly recommended as they minimise unavoidable errors introduced by moving the sensor. However, the procedure is long and arduous and therefore not recommended for those who need to use it frequently: the use of two sensors is recommended in such cases.

Unbalance measurement and the simultaneous calculation of the correction mass can be

started and stopped by pressing . Field balancing a rotating body is more often than

not an iterative procedure:

- a measurement is taken to determine the correction mass required

- the required mass is added to the rotating body, trying to observe the value and

position as much as possible

- a new unbalance measurement is taken to verify the effects of the correction

performed

- if the residual unbalance is still too high, it must be corrected again, and so on

When the correction required is lower than the desired tolerance, the balancing process can be considered complete. However, at this point it is advisable to verify the residual vibration, both of the synchronous component 1xRPM (connected to the unbalance), and the Overall global value (generated by other causes). The vibrometer function must be used for this purpose (see Chapter 5 – Vibrometer function) setting the same value for the synchronous filter width.

Two-plane balancing with a single sensor involves moving the same

Note:

If the signal is unstable the measurement value can oscillate considerably; in such conditions it is best to reduce the synchronous filter width for greater accuracy (see

5 – 4 Synchronous filter width) and consequently repeat the calibration.

Warning:

To ensure reliable results, the velocity of the rotating body should be as close as possible to that of the various calibration steps when the measurement is taken. As a general indication, variations of about 5%, more or less, can be considered acceptable.

To remind the operator that calibration is required after any of the balancing parameters are changed, they can only be changed from the calibration page (see 6 – 6 Calibration procedures), and not directly from the unbalance measurement page.

6 - 4 Balancing function

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).

quits the current balancing operation and starts a new calibration procedure

(see 6 – 6 Calibration procedure).

Displaying balancing results from the records

Balancing results loaded from the records are displayed in a special screen laid out as follows:

1. position number in the balancing record

2. date and time saved

3. synchronous filter width

4. value (in U units) and angular position of the initial unbalance on plane P1

5. value (in U units) and angular position of the final unbalance on plane P1

6. value (in U units) and angular position of the initial unbalance on plane P2

7. value (in U units) and angular position of the final unbalance on plane P2

8. rotation velocity of the rotating body

Balancing function 6 - 5

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

- Calibration for two-plane balancing with a single sensor:

1) first spin without test mass, with a sensor on plane P1

2) second spin without test mass, with a sensor on plane P2

3) third spin with test mass on plane P1, and a sensor on plane P1

4) fourth spin with test mass on plane P1, and a sensor on plane P2

5) fifth spin with test mass on plane P2, and a sensor on plane P1

6) sixth spin with test mass on plane P2, and a sensor on plane P2

The calibration page of the N300 instrument is laid out as illustrated here below:

1 2 3 4

1. channel that the measurement displayed refers to

2. status of the channel displayed:

= enabled

= disabled

3. type of sensor connected

4. calibration procedure steps

not yet completed

completed

The values displayed relate to the step selected (current), which is indicated by the symbol

5. synchronous filter width (see 5 – 4 Synchronous filter width)

6. value, unit of measurement and type of synchronous vibration

7. synchronous vibration phase (from 0° to 359°)

6 - 6 Balancing function

8. average velocity of the rotating body at the selected calibration step

9. velocity unit of measurement

10. value and angular position of the calibration mass

11. plane on which to apply the test mass

test mass on plane P1

test mass on plane P2

12. planes on which to apply the sensors

channel A sensor on P1, channel B sensor on P2

channel A sensor on P1

channel A sensor on P2

Note:

The average velocity value is very important as the calibration procedure can only be considered well-executed when the velocity between one step and another does not differ by more than 5%. The operator is responsible for controlling this condition.

Measurement settings

Settings used for balancing can only be changed by pressing

when the first step of the calibration procedure has been selected. The parameter that can be changed is displayed in negative, by pressing the and

arrows you can scroll through all of the values that can be selected.

With the and keys, you can move to the previous or next parameter.

Press to confirm the new parameter values; or press to quit the setting without changing the existing values.

1. Channel status

Channel B must be disabled if there is only one sensor; in this case, for two-plane balancing, the operator doesn’t have to do anything as the instrument will automatically switch to the single-sensor procedure.

Note:

If a client only has one sensor all he has to do is disable channel B after buying the instrument. The instrument will record this setting so that it doesn't have to be entered each time. If a second sensor is purchased, two-plane balancing can be performed using two sensors (simpler, quicker and less susceptible to errors) by simply enabling channel B.

Balancing function 6 - 7

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. Type of balancing

- single-plane

on 2 planes (with 1 or 2 sensors, determined according to the status of channel B)

8. Test mass

Calibration requires the use of one or more test masses, to be applied to a known

position on the various correction planes. These two parameters must be set using the

relevant additional functions test mass value

test mass position

only accessible from the usual bar during the first step in which the mass must be

applied:

- step 2 for single-plane balancing

- step 2 for the mass on P1 for two-plane balancing with two sensors

- step 3 for the mass on P2 for two-plane balancing with two sensors

- step 3 for the mass on P1 for two-plane balancing with a single sensor

- step 5 for the mass on P2 for two-plane balancing with a single sensor

The desired values can be obtained by changing one figure at a time. The and

arrows increase or decrease the figure selected (displayed in negative) by one unit. By

pressing the and keys, the figure on the left or on the right can be selected

respectively.

On completion, press to confirm or to cancel.

A different test mass can be specified (value and angular position) for plane P1 and plane

P2 in the case of two-plane balancing to accommodate various uses.

6 - 8 Balancing function

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. This can be considered satisfactory if at least one of the following occurred:

- the modulus varied by at least 30%

- the phase varied by at least 30°

Vibration measurement during the various calibration steps can be started and stopped by pressing . If the value is stable enough to not require repetition

of the measurement, you can proceed to the next step by pressing . Pressing the

key after the last calibration step will take you back to the unbalance correction

calculation page, where the operator will find the required correction masses.

Balancing function 6 - 9

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

This chapter refers to the "N instrument" or "N apparatus", generic expressions that refer exclusively to the N100 and N300 models with which CEMB N-Pro software can be used (communication, data organisation, printing, etc). The CEMB N-Pro software cannot be used with other CEMB instruments, including those from the N range.

System requirements

Installation and use of the CEMB N-Pro program requires:

- a processor: at least Intel Pentium IV 1GHz, or Athlon equivalent;

- memory: 512MB (recommended: 1GB or more);

- space on disk: at least 400MB free before installation (excluding space subsequently required for the data records);

- operating system:

- Microsoft Windows 2000 at least Service Pack 4

- Microsoft Windows XP at least Service Pack 2

- Microsoft Windows Vista

- Microsoft Windows 7

- video resolution 1024x768 or better.

Installation of the software

Installation of the CEMB N-Pro software must be carried out by launching the setup.exe program, contained in the CD-ROM, and then clicking on the key without changing any options. That way the software will be installed in the program directory.

Warning:

During installation of the software a file will be created containing the drivers for USB communication: it is therefore important that the CEMB N-Pro software is installed before the N100 or N300 instrument is connected to the PC, otherwise malfunctioning may occur.

CEMB N-Pro program (optional) 7 - 1

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 not connect the N instrument to the PC using the USB cable supplied until the CEMB N-Pro software has been correctly installed; after a few seconds the following message will appear:

- New hardware found

- USB <-> Serial

in the Windows application bar (lower right hand corner). The add new hardware window will then appear with the guided procedure. When requested to authorise Windows to connect to Internet to search for the drivers, select the option ‘No, not this time’ and press ‘Next >’.

- Then select ‘Install from a specific location (Advanced)’ and press ‘Next >’

again.

7 - 2

CEMB N-Pro program (optional)

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. Wait until the Windows application bar displays a new message:

- New hardware found

- USB Serial Port

and a second Found New Hardware guided procedure window appears. Repeat exactly the same steps to install the ‘USB Serial Converter’ hardware.

Correct communication between the PC and the N100 – N300 instruments is now possible.

Note:

To install the software and drivers correctly you must have administrator rights on the PC used; this is possible when you login as the Administrator.

CEMB N-Pro program (optional) 7 - 3

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.

CEMB customer service will reply by e-mail containing the corresponding activation code (AC)

The same must be entered to complete the procedure for registration and allow the use of the software.

Warning:

To successfully complete registration of the CEMB N-Pro software, it must be opened by a person with administrator rights on the PC. The program can then be opened and used by users with more limited rights.

Note:

Selecting “Register later” means the software can be used temporarily whilst waiting to receive the activation code from the CEMB customer service.

Warning:

Installation of the CEMB N-Pro software requires a different activation code for every PC, each one of which must be requested from CEMB in accordance with the procedure described above.

7 - 4

CEMB N-Pro program (optional)

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.

Function bar

The buttons are grouped together in the function bar according to type:

- data storage functions:

- copy the element selected

CEMB N-Pro program (optional) 7 - 5

- create a new folder

- display the contents of the upper folder

- search in the records

- move the element selected

- paste the element to be copied or moved in the position displayed

- delete the element selected

- rename the element selected

- 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.

- generate and display a report for the element selected

- generate and display a multi-report for the elements selected

- save the report (or multi-report) generated

- print the report (or multi-report) generated

- function for importing data from the N100 and N300 instruments:

- / start/quit the automatic procedure for importing data from the

N instrument using a USB connection

- general functions:

- open the settings window

- display a panel with information related to the software (producer,

version, etc.)

- quit the program

General settings

General operating parameters for the CEMB N-Pro software can be set from this window, such as:

- the PC port to which the N instrument will be connected

which will be one of the COMx serials available, a list of which can be displayed by clicking on the drop-down menu

Note:

To select the port correctly, proceed as follows:

- with the N instrument disconnected from the PC, click on the drop-down menu and select Refresh, noting the list of ports available

7 - 6

CEMB N-Pro program (optional)

- 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.

- the language for messages

which can be chosen from a drop-down menu

- Italiano

- English

- Français

- Deutsch

- Español

- the path of the basic folder (DB_N-Pro) of the PC’s data records

within which the program creates subfolders

- vibr for vibration measurements

- bal for balancing data

After setting the desired values, press .

To quit the window without setting anything, press .

Reading data from the N100 or N300 instrument

After connecting the N instrument to the PC, checking and if necessary changing the USB port setting, the CEMB N-Pro software can be used to automatically read all of the measurements contained in the instrument’s records, by simply pressing . After which, without pressing any key, wait for the message to appear marking the end of this procedure. Data reading progress is indicated by the progressive filling up of a horizontal bar. This procedure creates a folder in both records (vibration and balancing) named according to the current date and time in the AAMMGG_hhmmss format where:

- AA = last two figures of the year

- MM = month of the year (01 January; 02 February; … 12 December)

- GG = day of the month

- hh = hour of the day (00 … 23)

- mm = minutes (00 … 59)

- ss = seconds (00 … 59)

In this way measurements will automatically be displayed in the order in which they were imported.

Users with special or advanced requirements can name the folder as desired, or copy or move all or part of its contents.

CEMB N-Pro program (optional) 7 - 7

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. Likewise, the N100 model only measures and records vibration..

Data records imported from the N100 or N300 instrument

The CEMB N-Pro software subdivides the data records on the PC into two sub-folders, one for vibration measurements (symbol ) and one for balancing data ( ), which the

user is then free to manage as desired. Use the key to create folders and sub-folders to subdivide the data, for example by type, date, operator, location, etc. With the keys , and single files or entire folders can be copied or moved.

An element can be renamed or deleted by simply pressing a button.

There is also a useful search function to facilitate the use of the measurement records. Just insert the name (or part of it) of the element searched for.

If more than one element matches the search criteria entered, they will be displayed in

sequence by pressing the “Find next” button

7 - 8

CEMB N-Pro program (optional)

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

1. spectrum graph (not visible directly on the N100 or N300 instrument)

2. position and value of the cursor

3. overall vibration value

4. list of peak values

5. measurement information and parameters

6. notes associated with the measurements

Specific functions for the spectrum graphs:

- Cursor

The graph has a cursor that can be moved left or right one step at a time by clicking on or pressing .

By selecting, it is possible to click on the cursor directly and, by holding down the left mouse key, quickly drag it to the desired position.

- Zoom

Clicking on the key it is possible to choose from various zoom options:

- (enlarge rectangle) : the rectangle to be enlarged can be selected by clicking

on one point and dragging the cursor;

CEMB N-Pro program (optional) 7 - 9

- (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 point displays a larger area around it;

- Moving the graph in the window

After having selected it is possible to click on one point of the graph and, without

releasing the mouse button, move the whole graph within the window. In practice this changes the minimum and maximum extremes of both axes, without altering the scale. By dragging the cursor out of the window, the graph returns to the position it was in previously.

Note:

The minimum and maximum values of the axes can be modified individually by simply clicking on them and entering a new value using the keyboard.

7 - 10

CEMB N-Pro program (optional)

Synchronous vibration value measurement:

1. amplitude of the synchronous vibration value

2. phase of the synchronous vibration value

3. frequency of the synchronous vibration value

4. measurement information and parameters

5. notes associated with the measurements

Balancing data:

1 2

1. type of balancing (on one or two planes)

2. value (in generic U units) and phase of the initial imbalance

3. value and phase of the initial vibration

CEMB N-Pro program (optional) 7 - 11

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 . This is a valid help in the post-data analysis stage: the user can add comments or notes related to the values or type of measurement, but also regarding the acquisition conditions. Reminders for future work can be added, or other important notes. For example, in the case of balancing it is recommended to specify what physical units (mg,

g, kg, g· mm, g· cm, g· m, …) the generic U units correspond to.

Generation and printing of certificates (

reports

)

CEMB N-Pro software can be used to create and print customised certificates of vibration analysis and balancing results with extreme ease.

Press the key, then select a model (template) for the certificate to be generated. The model is a simple HTML file that the same user can create and customise to suit his own needs using any HTML editor. The CEMB N-Pro program generates the report automatically replacing some preset codes in the template with the corresponding values of the measurement displayed. The result is then displayed in a window and the following functions are enabled:

save the report just generated, specifying the name and position

print the

report

displayed, selecting a printer from those installed on the PC

Note:

If a virtual PDF printer is installed on the PC (e.g. PDFCreator, …), select

that to obtain a copy of the certificate in PDF format instead of a hard copy. It can then be named and saved on the hard disk in the desired location, so that it can be filed or even sent by e-mail. A hard copy can be obtained at a later date if required by printing off a copy of the PDF document.

7 - 12

CEMB N-Pro program (optional)

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:

Templates folder, it is best to save the edited model with another name or in a different folder. This is because subsequent N-Pro software updates will overwrite the templates distributed by CEMB with the program.

Note

The list of codes that can be used in the templates and their meanings, and some suggestions for the creation of customised certificates, are given in Appendix D.

If you wish to customise one of the templates present in the Report

Generating and printing multiple measurement certificates

multi-report

(

From version 1.3, CEMB N-Pro software allows you to create and print customised certificates containing different measurement and balancing data with extreme ease. This means a series of measurements taken at subsequent times, even for different points of different machines, can be grouped together in a single document. The certificate can be fully customised thanks to the extension of the template concept:. Predefined codes for multi-reports are composed of two parts:

• the code related to the information to be replaced (identical to a single

measurement report)

• the sequential number of the measurement to which the code refers

The steps for generating a multi-report are very simple:

1. use ‘CTRL + click’ or ‘SHIFT + click’ to select measurements from the data

records to be included in the multi-report, which must be contained in a single folder

)

2. press the button

3. select the desired template

Note:

templates are shown in Appendix D.

CEMB N-Pro program (optional) 7 - 13

The description, list and meaning of codes that can be used in multi-report

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, 6.0W MAX

- battery life: more than 8 hours based on typical use of the instrument

- Display

- STN monochrome 128x64 pixel

- LED backlit

- Keyboard

- on/off plus 9 keys

- Input channels

- 2 measurement channels (DC power supply max 5 mA, automatically

enabled/disabled according to the type of sensor)

- 1 photocell channel (velocity and angle reference)

- Connectable sensors

- CEMB TA-18S accelerometer

- CEMB T1/40 velocimeter

- general accelerometer or velocimeter, with a max. signal of 4 V-PP

- 60-18,000 RPM photocell

- high-speed photocell, up to 60,000 RPM.

- Measurement specifications

- A/D converter: 16 bit resolution

- Number of averages: from 1 to 16

- Synchronous filter width: from 1% to 100%

- Frequency range: up to 1kHz (60kRPM) max

- Data storage capacity: max 10 vibration measurements and 10 balancing operations

- Instrument’s limit of error: 5%

Technical data A - 1

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 Medium sized machines with electric motors from15 to 100 KW, without any special

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.

foundations. Lathes. Milling machines. Machines and drives up to 300 KW with rigid construction, without any parts with alternating movement, resting on their own foundations. Mass produced electric motors with axis height less than 130 mm.

MACHINES

III – G The most common medium category for first approximation. This category includes

machines not found in other categories. Large machines with rigid, heavy foundations, without any masses with alternating movement. Gas or steam turbines, turbo blowers, large alternators. Normal motors in general and especially motors whose axis height is from 130 to 230 mm. Rigid (class A) fans. Parts of machine tools.

IV – T

V – D

VI – S Machines with masses featuring unbalanceable reciprocating movement, mounted on

Large machines with low-rigidity foundations, without any masses with alternating movement. Turbines, alternators, large motors, on light foundations or on board ship. Electric motors with axis heights from 230 to 330 mm. Hydraulic machines, centrifugal pumps. Normal fans on flexible structures (class B). Turbine gears. High performance machinery: for printing, spinning or papermaking. Machines with unbalanceable alternating masses, on foundations that are rigid in the direction of the greatest vibrations. Fans on vibrating-damping mounts (class C). Motors with crankshafts with six or more cylinders on their own foundations. Piston motors for automobiles, goods vehicles, transportation vehicles not set on insulators during tests. Machinery with unbalanceable masses, such as weaving looms, skimmers, centrifugal purification plants, washing machines if fitted to rigid baseplates without any shock absorbers.

flexible foundations. Machines with free rotating masses, having variable, non-compensable unbalances, with flexible mounting, operating without rigid connections to other parts, such as: washing machines, spin-dryer baskets, vibrating sieves, machines for fatigue testing of materials, vibrating machines for technological processes, beaters for grinders, vibratory equipment. Agricultural machines, mills, threshing machines. Engines with 4 or more cylinders mounted on motor vehicles and locomotives. Diesel engines with 4 or more cylinders. Marine diesel engines. Large two-stroke engines.

Evaluation criteria B - 1

EVALUATION CRITERIA BASED ON THE SPEED OF VIBRATION MEASURED ON FIXED PARTS

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.

The class to which the machine under test belongs is identified with the aid of Table A. The graph of page B-3 provides a direct evaluation of the vibratory state, e.g. if the vibration measurement on the support of a grinding machine (class 1) is 5 mm/s (RMS) evaluation is: the vibration is not admissible, hence its cause should be investigated and removed.

The criterion based on the speed is valid for frequencies lying between 10 Hz and 400 Hz. Under the frequency of 10 Hz it is possible to have incorrect evaluation because the vibrations, although having permissible speeds, would have prohibitive amplitudes of displacement.

With frequencies below 10 Hz, it is necessary to consider the criterion based on the displacements; while for frequencies exceeding 400 Hz, sometimes also in the range from 300 to 400 Hz, evaluation ratings based on speed should be considered with precaution, because at such frequencies certain phenomena assume a different aspect and it is necessary to take into account the energy radiated in the surrounding environment as well as the vibrations of the building or the environment (ships, aircraft, vehicles) and of the human physiological interferences. For high frequencies, measurements of acceleration could prove useful.

The classification of Table A and the acceptability values given in the graph are partially in agreement with ISO 10816. The ISO standard does not contemplate classes V and VI; moreover it makes reference to specific standards either already published or due for publication regarding every type of machine (electric motors, hydraulic machines, gas turbines, etc.).

B - 2 Evaluation criteria

RMS velocity (mm/s)

not admissible

accettable

admissible

good

uman sensitivit

Graph for evaluating mechanical vibrations on the basis of the RMS velocity.

Evaluation criteria B - 3

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

≅

n with knocking

2) f

3) f ≅ (0,40 ÷ 0,45) n

4) f = ½ n Mechanical weakness in

5) f = 2n Misalignment.

6) f is an exact multiple of n

bodies.

Rotor inflection.

Resonance in rotating bodies.

Roller bearings mounted with eccentricity.

Misalignments.

Eccentricity in pulleys, gears, etc.

Irregular magnetic field in electrical machines.

Belt length an exact multiple of the pulley circumference.

Gear with defective tooth. An unbalance vibration often also intervenes.

Alternating forces Second and third harmonic present

Mechanical unbalance defect superimposed on irregular magnetic field.

Defective lubrication in sleeve bearings.

Faulty roller bearing cage. Check for harmonics

rotor.

Sleeve bearing shells loose.

Mechanical yield.

Mechanical looseness.

Roller bearings misaligned or forced in their housings. Defective gears.

Misalignments with excessive axial play.

Rotors with blades (pumps, fans).

Intensity proportional to unbalance, mainly in the radial direction, increases with speed.

Axial vibrations sometimes sensitive.

Critical speed near n with very high intensity.

Recommend balancing the rotor on its own bearings.

Considerable axial vibration also present, greater than 50% of the transverse vibration; also frequent cases of f = 2n, 3n.

When the rotation axis does not coincide with the geometric axis.

Vibration disappears when power is cut off.

Stroboscope can be used to block belts and pulleys at the same time.

In asynchronous motors, the knocking is due to running.

For high n, above the 1° critical level.

Check with stroboscope.

Precision journal movement (oil whirl).

This is a sub-harmonic, often present but hardly ever important. f = 2n, 3n, 4n and semi-harmonics also often present.

There is strong axial vibration.

Loose bolts, excessive play in the mobile parts and bearings, cracks and breaks in the structure: there are upper grade sub-harmonics.

Frequency = n x number of spheres or rollers. Check with stroboscope. f = z n (z = number of defective teeth). Because of general wear, teeth badly made if z = total number of teeth.

Often caused by mechanical looseness.

f = n x number of blades (or channels)

A rapid guide to interpreting a spectrum C - 1

7) f is much greater than n, not an exact multiple

8) f = natural frequency of other parts

9) f unstable with knocking

10) f = n

n ≠ n

12) f = fc < n or f = 2 fcBelt with defective elasticity

Damaged roller bearings. Unstable frequency, intensity and phase. Axial

Excessive wear on sleeve bearings.

Belts too tight. Characteristic audible screech.

Multiple belts not homogeneous.

Low load gears. Teeth knock together because of insufficient load;

Rotors with blades for fluid management (cavitation, reflux, etc.).

Excessive play on sleeve bearings.

Belts disturbed by vibrations from other parts.

Multiple belts not homogeneous.

Belts with multiple joints.

( nc = critical speed of shaft) Roller bearings.

(nr = mains frequency) Electric motors, generators.

in one area.

vibration.

Completely or locally defective lubrication.

Audible screech.

Run between the belts.

unstable vibration.

Unstable frequency and intensity. f = n x number of blades x number of channels. Frequent axial vibration.

Oil whip caused by vibrations in other parts.

Check with stroboscope.

Examples: eccentric or unbalanced pulleys, misalignments, rotor unbalances.

Unstable intensity.

For rotors above the 1st critical speed.

Harmonics also present.

fc is the belt frequency.

= π D n / l (D = pulley diameter; l = belt length).

Considerable axial vibrations, more than 10% of the transverse vibration, may be caused

typically by:

- misalignment (more than 40%);

- shaft inflection, especially in electrical

motors;

- defective thrust bearings;

- elliptic eccentricity in the electric motor

rotor;

- distorted foundations;

- wear in stuffing box seals, etc.;

- rotor side rubbing;

- defective radial bearings;

- defective coupling;

- defective belts.

- forces deriving from tubing;

C - 2 A rapid guide to interpreting a spectrum

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. MISALIGNMENT

A rapid guide to interpreting a spectrum C - 3

3. MECHANICAL LOOSENESS/PLAY

4. BELT

5. GEARS

C - 4 A rapid guide to interpreting a spectrum

6. SLEEVE BEARINGS

7. ROLLER BEARINGS

8. ELECTRIC MOTORS

A rapid guide to interpreting a spectrum C - 5

3. FORMULAE FOR CALCULATING TYPICAL BEARING DEFECT

FREQUENCIES

SYMBOLS:

FTF = housing frequency BPFO = defect on outer track BPFI = defect on inner track BSP = defect on roller/ball

The frequencies of bearings can be calculated if we know: S = number of shaft rpm PD = primitive diameter BD = ball/roller diameter N = number of balls/rollers Θ = angle of contact

The most common case:

a - fixed external ring (rotating internal ring)

BD PD

⎛ ⎜

⎜ ⎝

⎛ ⎜

⎝

Θ⋅

⎞ ⎟

⎠

⎞ ⎟

⎠

BD PD

⎤ ⎥

⎦

⎤

Θ⋅

⎥ ⎦

⎤

Θ⋅

⎥ ⎦

⎤

cos

⎞ ⎟

Θ⋅

⎥

⎟ ⎠

⎥

⎦

⎞ ⎟

⎠

⎡

=FTF 1

⎢

⎣

=BPFO 1

=BPFI 1

PDS

⎛

⋅

=BSP

⎜

⎝

BDS

⎞

⎛

−⋅ cos

⎟

⎜

⎠

⎝

⎡

⎛

−⋅⋅ cos

⎜

⎢

⎝

⎣

⎡

⎛

⋅⋅ cos

⎜

⎢

⎝

⎣

⎡

⎞

−⋅

⎢

⎟ ⎠

⎢

⎣

b - rotating external ring (fixed internal ring)

BD PD

⎛ ⎜

⎜ ⎝

⎛ ⎜

⎝

Θ⋅

⎞ ⎟

⎠

⎞ ⎟

⎠

BD PD

⎤ ⎥

⎦

⎤

Θ⋅

⎥ ⎦

⎤

Θ⋅

⎥ ⎦

⎤

cos

⎞ ⎟

Θ⋅

⎥

⎟ ⎠

⎥

⎦

⎞ ⎟

⎠

⎡

=FTF 1

⎢

⎣

=BPFO 1

=BPFI 1

PDS

⎛

⋅

=BSP

⎜

⎝

BDS

⎞

⎛

+⋅ cos

⎟

⎜

⎠

⎝

⎡

⎛

−⋅⋅ cos

⎜

⎢

⎝

⎣

⎡

⎛

⋅⋅ cos

⎜

⎢

⎝

⎣

⎡

⎞

−⋅

⎢

⎟ ⎠

⎢

⎣

Approximate calculation formulae (± 20%)

FTF = 0.4 x S (a) or 0.6 x S (b) BPFO = 0.4 x N x S (a) or (b) BPFI = 0.6 x N x S (a) or (b) BSP = 0.23 x N x S (N < 10) (a) or (b)

= 0.18 x N x S (N ≥ 10) (a) or (b)

C - 6 A rapid guide to interpreting a spectrum

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.

To ensure they are replaced correctly, only the following codes should be used:

#1# Current date

#2# Current time

#3# Note number 1 added to the measurement

#4# Image of the spectrum graph for channel A

#5# Image of the spectrum graph for channel B

#6# Name of the measurement

#7# Path of the file containing the measurement

#8# Serial number of the N100 or N300 instrument

#11# Type of measurement (Pk, PP, RMS)

#12# Type of sensor connected to channel A

#13# Type of sensor connected to channel B

#14# Measurement (overall, 1xRPM, 2xRPM, …)

#15# Number of averages (only for overall measurement)

#16#

#17# Maximum frequency measured (only for overall measurement)

#18# Number of lines in the spectrum

Synchronous filter width, expressed as a % (only for synchronous

measurements or balancing)

#19# Note number 2 added to the measurement

#20# Note number 3 added to the measurement

Model of apparatus used to take the measurement

#48#

Information related to the creation of

(N100, N300)

Templates

D - 1

#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 vibration frequency - channel A

#332# Synchronous vibration frequency - channel B

#351#

Units of measurement for vibration (g, mm/s, µm, …)

#401# Vibration peak 1 frequency – channel A

#402# Vibration peak 2 frequency – channel A

#...# Vibration peak … frequency – channel A

#405# Vibration peak 5 frequency – channel A

#426# Vibration peak 1 value – channel A

#427# Vibration peak 2 value – channel A

#...# Vibration peak … value – channel A

#430# Vibration peak 5 value – channel A

#451# Vibration peak 1 frequency – channel B

#452# Vibration peak 2 frequency – channel B

#...# Vibration peak … frequency – channel B

#455# Vibration peak 5 frequency – channel B

#476# Vibration peak 1 value – channel B

D - 2

Information related to the creation of

Templates

#477# Vibration peak 2 value – channel B

#...# Vibration peak … value – channel B

#480# Vibration peak 5 value – channel B

#601# Initial unbalance value on plane P1 (in U units)

#602# Initial unbalance phase on plane P1 (in degrees °)

#603# Initial vibration value on plane P1

#604# Initial vibration phase on plane P1 (in degrees °)

#605# Current (final) unbalance value on plane P1 (in U units)

#606# Current (final) unbalance phase on plane P1 (in degrees °)

#607# Initial unbalance value on plane P2 (in U units)

#608# Initial unbalance phase on plane P2 (in degrees °)

#609# Initial vibration value on plane P2

#610# Initial vibration phase on plane P2 (in degrees °)

#611# Current (final) unbalance value on plane P2 (in U units)

#612# Current (final) unbalance phase on plane P2 (in degrees °)

In the case of multi-reports (certificates produced by grouping together data from N different measurements) #x-y# format codes must be used, where

- x = numeric code listed in the previous table

- y = sequential number of the measurement of which the multi-report is composed (1,

2, … N)

For example:

- #6-1# = name of measurement No. 1 of the multi-report

- #11-2# = type of measurement No. 2 of the multi-report

- …

Suggestions for customising certificates

The HTML model (template) used to create the certificates leaves clients free to customise the certificates distributed by CEMB together with the program, or to create new ones as desired. Clients with special requirements can insert logos or images and change the size and colour of the wording themselves.

As these templates are HTML documents they should be created or edited using appropriate programs known as HTML editors. They are used in a similar manner to normal word processing programs (Microsoft Word, Openoffice Writer, etc), with the exception that documents are generated and saved directly in HTML format: this means that the document’s graphic appearance remains unaltered when saved. On the contrary, if a word

Information related to the creation of

Templates

D - 3

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.net/

W3C Amaya multilingual, it can be downloaded free of charge from the

website http://www.w3.org/Amaya/

Mozilla Composer multilingual, part of the Mozilla Seamonkey suite, it can be

downloaded free of charge from the website

http://www.seamonkey-project.org/

- Adobe Dreamweaver multilingual, available at a cost

To assist users, KompoZer is included in the CD together with the CEMB N-Pro software.

Creation of certificates in

PDF

format

To generate certificates in PDF format, install a virtual PDF printer on the PC and select it

after pressing the key in the CEMB N-Pro software.

If you do not yet have this type of printer, PDFCreator can be installed, which can be

downloaded free of charge from the website http://sourceforge.net/projects/pdfcreator/

Once installed a new printer named PDFCreator will be displayed in the ‘Printers and fax’ window alongside the real printers connected to the PC.

D - 4

Information related to the creation of

Templates

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 the current self-learning step of the balancing operation

angular position of test mass used in the current self-learning step of the balancing operation

save the current measurement in the records

load and display the measurement selected from the records

delete the measurement selected from the records

empty the records (delete all measurements)

List of symbols used for the instrument E - 1

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 backlighting turns off automatically, calculated from when the last key is pressed

time after which the instrument turns off automatically, calculated from when the last key is pressed

Measurement information

measurement in progress/taken on channel A

measurement in progress/taken on channel B

sensor connected to the channel displayed: the instrument enables the channel for measurement

sensor not connected to the channel displayed: the instrument disables the channel (does not take the measurement)

overall vibration value

number of measurements averaged for calculation of the overall vibration

synchronous vibration value at the rotation velocity

synchronous vibration value at the third harmonic of the rotation velocity

synchronous filter width

vibration expressed in g (1 g = 9.81 m/s2)

E - 2 List of symbols used for the instrument

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 = 25.4 µm)

measurement of the effective vibration value

measurement of the peak vibration value

measurement of the peak-peak vibration value

frequency and velocity expressed in revs per minute (RPM)

frequency and velocity expressed in rotations per second (Hz)

channel disabled (measurement not taken)

vibration exceeds the instrument’s maximum measurement limit

amplitude and frequency of the vibration’s highest component

signal indicating no velocity, or velocity below the minimum allowed value

velocity exceeds the maximum allowed value

unstable velocity

single-plane balancing (static)

two-plane balancing (dynamic) using two sensors

two-plane balancing (dynamic) using a single sensor positioned on plane P1 or P2, respectively

correction for addition of material

list of steps in the self-learning procedure for balancing operations

current calibration step indicator

calibration step to be executed

calibration step executed

test mass used for self-learning

List of symbols used for the instrument E - 3

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 any other key to quit

press OK to confirm the previously selected operation or any other key to quit

measurement in progress: await completion

measurement process active: press OK to stop it when you wish to accept the result

connection to PC active: start the CEMB N-Pro software to transfer the data

Battery status

battery fully charged

battery partly charged

battery almost flat

battery flat: recharge within 5 minutes

E - 4 List of symbols used for the instrument

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. Just as when machining a piece in a workshop it is never possible to mach drawing sizes with perfect exactness and it is necessary to predetermine a “machining tolerance”, which varies in accordance to the requirements of each single piece, also when balancing, the precision obtained has to suit the needs of each

single piece, which is achieved by fixing a “maximum permissible residual unbalance” or “balancing tolerance”.

It is obvious that an insufficiently balanced piece will cause intolerable vibrations with all consequent malfunctions or damage. However, it would be clearly useless to balance a rotor to a degree of quality greater than required for a regular and normal operation of the machine incorporating that part, by using a balancing machine to its peak precision. In fact, exaggerating the quality requirements would only result in a waste of time and a higher balancing cost, without improving the quality of the rotor.

When fixing the balancing tolerance, the concept of “reproducibility” should also be borne in mind, i.e. the minimum value that can be certainly reproduced on repeated testing. For example: if with the simple operation of disassembling and reassembling a piece on the balancing machine or of balancing it at different times on the machine itself there is a variation in eccentricity of 5 microns, it is quite useless to balance that piece with a much greater precision than 5 microns.

are different according to whether the rotor may be considered rigid or flexible, similarly, the balancing accuracy or tolerance is different in the two cases. Suffice to say that in a flexible rotor, the effect of unbalance is amplified by the elasticity in such a way as to generate in the pedestals different forces than those created by a rigid rotor with the same unbalance. We can deduce, all other conditions being equal, that the balancing tolerances of the two cases will be different in the presence of equal forces or vibrations on the pedestals.

The contents of this pamphlet may be considered to be valid only for rigid rotors, unless otherwise specified.

UNIT OF MEASUREMENT OF BALANCING TOLERANCE

Balancing tolerance is given by the product of the maximum permissible unbalance by its distance from the rotational axis.

If the balancing tolerance is divided by the weight of the rotor, we obtain the “specific unbalance”. This is also called the “residual permissible eccentricity” as, in the case of static unbalance, it expresses the eccentricity of the rotor’s barycentre from the rotational axis caused by the permissible unbalance.

It is therefore necessary to calculate and prescribe the technical and economically most effective levels of balancing tolerance for each type of rotor.

The drawing should, therefore, always show:

- the value of the maximum permissible residual unbalance for each of the correction planes, with precision;

- where and how compensating weights should be added; or where material may be removed without damaging the piece;

- the journals that should support the rotor on the balancing machine;

- the recommended speed range for balancing;

- all other useful data from case to case, that may help to enable the user to carry out balancing operations quickly and safely.

This applies to rigid rotors; for flexible rotors, other specifications should be applied. Just as balancing operations

SYMBOLS

p (grams) = maximum permissible unbalance

r (mm) = p ’s distance from the rotational axis

P (kg) = rotor weight

n (rpm)= normal service rotational speed

p·r (gr·mm) = maximum permissible residual unbalance

rp ⋅

e =

G (mm/s) = balancing grade (see table)

= residual permissible eccentricity (micrometer)

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.

Grade

G ROTOR TYPE

mm/s

0,4 Gyroscopes

Spindles, discs and armature of precision grinders

Spinning spindles

1,0 Small electrical armatures with high level balancing requirements

Tape-recorder and phonograph (gramophone) drivers, cinema projectors High precision grinding machine drives Rotors of turbines and compressor of high-speed jet engines Rotor of steam turbines with high level balancing requirements

2,5 Rotors of steam and gas turbines, of turbo-generators, of turboblowers and of turbine pumps

Merchant ship main turbines

Superchargers, supercompressor for aircraft

Medium and large electrical armatures with high level balancing requirements Small electrical armatures with a reasonable level of balancing requirements, for high quality domestic electric appliances,dentist’s

drills, aerosols

Small electrical armatures not included in the conditions specified for Grade 6.3 Machine-tool drives

Fans for air-conditioning in hospitals and concert halls High speed reduction gears (over 1000 rpm) for marine turbines

Disc and drums of computer memories

6,3 Small mass produced electrical armatures in applications where they are not sensitive to vibrations or with antivibrating mounting

Medium and large electrical armatures (with shaft height at least 80 mm) without any special requirements Machine tools and components of machine tools and of machines in general

Fast moving weaving and spinni ng looms, plaiting machines, centrifuge drums (creams separators, cleansing plants, washing machines) Hydraulic machine rotors

Fly-wheels, fans, centrifugal pumps Reduction gear for merchant navy marine propulsion turbines Cylinders and rollers for printing machines Gas turbine rotors for the aeronautical industry Separated components of engines under special requirements

16 Drive and cardan shafts with high level balancing requirements

Parts for agricultural, grinding and threshing machines Motor parts for vehicles, commercial vehicles and locomotives (petrol or diesel drive) Crankshafts complete with fly-wheels and clutches with 6 or more cylinders with high level balancing requirements

Drums for slow centrifuges Propellers for light boats (motor boats. hydrofoils) Wheel-rims for car and motorbikes Normal drive pulleys Large cylinders for paperworks Single-piece tools for wood-working machines.

40 Wheels and wheel-rims for cars

Drive shafts and complete axles for vehicles Crankshafts complete with fly-wheels and clutches for 4-stroke engines with 6 or more cylinders mounted elastically, with piston speed greater than 9 m/s Crankshafts complete with fly-wheels and clutches for car, lorry and locomotive engines

Drive shafts for pulleys Multi-piece tools wood-working machines

100 Complete crankshafts for diesel motor of six or more cylinders with a piston speed greater than 9 m/s

Complete engines for vehicles and locomotives

Crankshafts for 1, 2 or 3 cylinder engines

250 Complete crankshafts for rigidly-mounted, 4 cylinder diesel engines: with piston speed greater than 9 m/s

630 Complete crankshafts for large rigidly-mounted, 4-stroke engines

Complete crankshafts for elastically mounted marine diesel engines

1600 Complete crankshafts for large rigidly-mounted, 2-stroke engines

4000 Complete crankshafts for rigidly-mounted marine diesel engines, with any number of cylinders, with a piston speed lower than 9 m/s

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 residual permissible eccentricity may then be deduced from the graph, as a function of the rotational speed, in correspondence with the G grade.

The residual eccentricity is not a fixed value: it may vary for a given G grade between a minimum and a maximum, corresponding to the two fine lines above and below the line of the G grade, according to the rotor type and purpose and to the construction characteristic of the machine on which the rotor will be mounted.

The balancing tolerance in gr·mm may be obtained from the residual eccentricity e (micrometers) multiplied by the rotor weight P (kg).

The tolerance values obtained are generally a good guide and sufficient to ensure satisfactory service conditions to a great extent. Some corrections may, however, be opportune and sometimes necessary, particularly when the machine has construction characteristics substantially different from those of traditional machines of the same category.

CONDITIONS OF VALIDITY OF THE BALANCING TOLERANCE GRAPH

1. The balancing values refer to the entire rotor; if there are two

planes of correction and if the rotor is approximately symmetrical, each correction plane should be allotted a tolerance value equal to half the value found, as long as the correction planes are symmetrical with respect to the barycentre and the pedestals; in

the case of marked asymmetry in the rotor or in the position of the correction planes, the residual unbalance must be divided accordingly between the two planes of correction.

2. The tolerance values arc valid both for static and for couple unbalance.

3. A rotor should be considered to be rigid over its complete range of service speeds and in the actual working conditions of the machine itself (bearings, pedestals, bedplates, foundations, couplings with other rotors, drive elements, etc.).

NOTE 1 - Balancing grades 0,4 and 1

For class 0,4 and 1 rotors, balancing tolerance must normally be checked with the direct experimental method.

The influence of the means of rotor drive and of the bearings may be significant.

NOTE 2 – Use of auxiliary equipment

For rotors that must be mounted on auxiliary shafts or flanges for balancing, the tolerances shown are only meaningful if, as well as the

unbalance of the auxiliary shaft or flange, the play of the mounting and the working tolerance of the piece are checked for their concentricity with the rotational axis, both for the residual unbalances and of the ultimate shaft. The sum of the residual unbalances and of the plays, converted into eccentricity values, must, of course, be lower than the balancing tolerance, as the balancing accuracy obtained would otherwise be purely illusory.

NOTE 3 - Assembled rotors

For assembled rotors the unbalance of the component parts must be summed together vectorially, also bearing in mind the unbalance that derives from the mounting (machining tolerances, clearances, keys, set screws, etc.).

The unbalance resulting after the assembling should be lower than that indicated by the graphs for the complete rotor; if it is not, the rotor should be balanced after assembly, selecting two suitable planes of correction.

DIVIDING THE PERMISSIBILE RESIDUAL UNBALANCE BETWEEN TWO CORRECTION PLANES

In most rotors, a reasonable division of the total permissible

residual unbalance U of the rotor is possible between the two

correction planes using one of the following methods; choose the method according to the conditions specified.

Us and Ud are used to indicate the respective permissible residual unbalances for the left and right correction planes (see figures).

indicates the rotor’s barycentre.

1) If

With

UUU

hh ≠

but

;

s <

with

hh ≅ we can consider

bhb

7,03,0 <<

we can consider

DIRECT EXPERIMENTAL METHOD

The most accurate and safest value of the maximum permissible residual unbalance can only be obtained with direct experiments. To do this, balance the rotor on a balancing machine as accurately as possible, then fit it on its ultimate machine in service conditions. In successive tests, add increasing unbalances, until the vibrations of the pedestals or of the machine become significant. Now establish the maximum permissible unbalance in relation to the value found, e/g. one third.

This testing must be systematic, so as to take all possible cases of vibration and all possible conditions of the rotor and of the position of the added unbalances into consideration.

2) If

it is advisable to consider a greater value of

lb >

overall unbalance to be divided as above

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:

VVV +=

where

V ⋅

⋅π=

(Volume of cylindrical pan) and

3) If

it is advisable to use an auxiliary plane P

b <

(which may coincide with Ps or Pd) for which the

maximum permissible unbalance is

furthermore, for planes Ps and P

432

4) The permissibile residual unbalance for one correction plane is usually given by the product of the overall permissible residual unbalance of the entire rotor and the relationship between the distance of the other correction plane from the rotor’s barycentre and the distance between the correction planes.

If the rotor does not come under any of the simplified methods listed, you must follow the general method, which is valid for any rotor and any position of the correction planes.

The general method is set out in CEMB Technical Booklet N° 8 (which can be sent f.o.c. on request), and in International Standard N° 1940/1 (1986-09-1).

1hd

V ⋅

⋅π=

hhh −=

;

− 323

1085.7 dhdP

⋅=

(Volume of conical part)

æ ç

°= 30tan

1511.0

(1) becomes:

⋅−

(2)

DRILLING IN ALUMINIUM, CAST IRON etc.

Once you know the weight that has to be removed, you must multiply it by a correction coefficient designed to take the different densities of the materials into account. The resulting weight is used in diagrams 1 to 5 to determine the correct value of hole depth (h).

TABLE OF CORRECTION COEFFICIENTS

MAT D Reference Correction coefficient

density (7.85/D) (Kg/dm3)

ALUMINIUM 2.7 2.91

CAST IRON 7.25 1.09

BRASS 8.5 0.92

COPPER 8.9 0.88

EXAMPLE:

Unbalance to remove P = 10 grams. Drill bit used d = 14 mm. Rotor material ALUMINIUM. Corrected P value = 10x2.91 =

29.1 Diagram 1 gives us h = 27 mm

PRACTICAL USE DIAGRAMS FOR

CORRECTING UNBALANCE

DRILLING IN STEEL:

Use diagrams 1 to 5 according to need. Each diagram supplies the depth of the drill hole (h), as a function of the weight to be removed (P) and the diameter of the drill bit (d). The curves are plotted for steel (density 7.85 kg/dm3), taking the conical shape (120°) of the drill bit into account, using the following criterion:

Unit of measurement:

CORRECTING BY ADDING WEIGHT TO STEEL:

Use diagram 6. This supplies the weight of a 1 cm long plate, as a function of the commercial dimensions of thickness (S) and width (L). Divide the unbalance by the weight obtained from the diagram to obtain the length (l).

EXAMPLE: Unbalance to add 50 grams

Plate used 50x10 mm.

Diagram 6 gives us a weight of P = 39 grams/cm

3.1

therefore

==l

cm.

1 - GENERAL DIAGRAM OF WEIGHT REMOVABLE BY DRILLING IN STEEL

(For small weight see diagrams 2 – 3 – 4 – 5)

Cone only

Weight removed in grammes

Hole depth (h) in mm

2 - DIAGRAM FOR FINE DRILLING Ø 0,5 – 1,5 mm

Cone only

Weight of material removed (steel) in milligrammes

Hole depth (h) in mm

3 - DIAGRAM FOR FINE DRILLING Ø 1 – 6 mm

Cone only

Weight of material removed (steel) in grammes

Hole depth (h) in mm

4 - DIAGRAM FOR FINE DRILLING Ø 2 – 10 mm

Cone only

Weight of material removed (steel) in grammes

Hole depth (h) in mm

5 - DIAGRAM FOR FINE DRILLING Ø 5 – 12 mm

Cone only

Weight of material removed (steel) in grammes

Hole depth (h) in mm

6 - DIAGRAM OF WEIGHT per cm OF A STEEL PLATE AS A FUNCTION OF DIMENSIONS L - s

Width of plate (L)

in mm

Weight of plate in g/cm

Thickness of plate (s) in mm

CEMB USA N300 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual