INTERNATIONAL

STANDARD.
INTERNATIONAL ORGANIZATION FOR STANDARDIZATION l MEXAYHAPOAHAJI OPTAHM3ALWI I-IO CTAHAAPTW3AUIiIM l ORGANIZATION INTERNATIONALE DE NORMALISATION

Mechanical vibration of rotating and reciprocating machinery -

Requirements for instruments for measuring vibration
severity
Vibrations me caniques des machines tournan tes ou al terna tives - Spe’cifications
des appareils de mesurage de
Kin tensite’ vibra toire iTeh STANDARD PREVIEW
First edition - 1975-07-l 5 (standards.iteh.ai)
ISO 2954:1975
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a1c00183171a/iso-2954-1975

UDC 621-12/-13 : 534.1 : 53.082 Ref. No. IS0 2954-1975 (E)

Descriptors : machinery, rotating machines, reciprocating engines, tests, measurement, vibration, vibration meters.

Price based on 6 pages

IS0 (the International Organization for Standardization) is a worldwide federation
of national standards institutes (IS0 Member Bodies). The work of developing
International Standards is carried out through IS0 Technical Committees. Every
Member Body interested in a subject for which a Technical Committee has been set
up has the right to be represented on that Committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work.

Draft International Standards adopted by the Technical Committees are circulated

to the Member Bodies for approval before their acceptance as International
Standards by the IS0 Council.

International Standard IS0 2954 was drawn up by Technical Committee

ISO/TC 108, Mechanical iTeh STANDARD PREVIEW
vibration and shock, and circulated to the Member Bodies
in January 1973.
(standards.iteh.ai)
It has been approved by the Member Bodies of the following countries :
Belgium Italy
ISOSweden
2954:1975
Bulgaria https://standards.iteh.ai/catalog/standards/sist/aa78fd19-f56f-4ba5-8feb-
Japan Thailand
Czechoslovakia New Zealand a1c00183171a/iso-2954-1975
Turkey
Egypt, Arab Rep. of Portugal United Kingdom
France Romania U.S.A.
Germany South Africa, Rep. of U.S.S.R.

The Member Body of the following country expressed disapproval of the

document on technical grounds :
Australia

0 International Organization for Standardization, 1975 l

Printed in Switzerland
INTERNATIONAL STANDARD IS0 2954-1975 (E)

Mechanical vibration of rotating and reciprocating machinery -

Requirements for instruments for measuring vibration
severity

1 SCOPE AND FIELD OF APPLICATION 3 GENERAL REQUIREMENTS

This International Standard states the requirements which a A vibration measuring instrument usually consists of : a
measuring instrument for vibration severity of machines vibration pickup; an indicator set which contains an
should meet if inaccuracies of measurement, particularly amplifier, correcting filter networks for the frequency
when making comparisons between one machine and response and an indicating or recording instrument; and
another, are not to exceed a specific value. Instruments a power supply system.
meeting the requirements of this International Standard are
The requirements described in this clause apply to the
suitable for use in carrying out the procedures specified in
general characteristics of the complete assembly of the
IS0 2372 and IS0 2373 and are designated “Measuring
pickup and the true v,,, indicator set. Clauses 4 and 5
instruments for vibration severity in rotating and
contain the detailed requirements for each of these main
reciprocating machines”.
units.
The instruments covered by this International Standard give
iTeh STANDARD3.1measuring
PREVIEW
direct indication or recording of root-mean-square vibration
velocity, which is defined as the measuring unit of the
The frequency range of the vibration
instrument shall be from 10 to 1 000 Hz.
severity

vibration severity. (standards.iteh.ai) NOTE - This means that the frequency range corresponds to the
frequency interval employed in the evaluation scale in IS0 2372.
NOTES
ISO 2954:1975
1 A method of checking true root-mean-square indication is 3.2 The sensitivity within the measuring-frequency range
described in an annex.
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shall not deviate from the reference sensitivity at 80
a1c00183171a/iso-2954-1975 Hz by
2 Subject to limitation of the measuring-frequency range, these more than the quantities given in the table.
instruments may be used for other applications where similar
accuracy of measurement is required, for example measurement of
vibration velocity of structures, tunnels, bridges, etc.
TABLE - Sensitivity relative to the reference sensitivity
at 80 Hz and limiting values of the permissible deviation
within the frequency interval from 1 to 10 000 Hz

I
Relative sensitivity
Frequency
2 DEFINITIONS HZ Nominal value Minimum value Maximum value
The terms used in this International Standard are defined in
1 - - 0,Ol
the following IEC Publications and IS0 International
Standards : 2,5 0,016 0,Ol 0,025

10 ItO 033 I,1

IEC 184, Methods for specifying the characteristics of
electromechanical transducers for shock and vibration 20 I,0 089 ItI
measuremen 6. 40 I,0 a9 I,1
80 LO 1 to 1 ,o
IEC 222, Methods for specifying the characteristics of
auxiliary equipment for shock and vibration measurement. 160 180 03 I,1
500 I,0 03 I,1
IS0 2041, Vibration and shock - Vocabulary.
1 000 LO 03 ItI
IS0 2372, Mechanical vibration of machines with operating 4 000 0,016 0,Ol 0,025
speeds from 10 to 200 rev/s - Basis for specifying
10000 - - 0,Ol
evaluation standards.
IS0 2373, Mechanical vibration of certain rotating
electrical machinery with shaft heights between 80 and To minimize measurement errors caused by the interference
4OOmm- Measurement and evaluation of the vibration due to vibrations with frequencies outside the
severity. measuring-frequency range, the sensitivity shall decrease

1
IS0 2954-1975 (E)

rapidly in a clearly defined manner at the limits of the 3.4 The error of the vibration severity measuring
frequency range. Both the required nominal values of the instrument is composed of the permissible deviations for
sensitivity and the permissible minimum and maximum the frequency response in accordance with 3.2 and the
values are given in the table. error in the absolute value of the sensitivity at the reference
frequency of 80 Hz (i.e. calibration error). The
To preclude doubts about the course of the sensitivity
measurement error may be up to a maximum of * 10 % of
between the cutoff frequencies shown in the table, figure 1
the indicated value, including the calibration error, at
illustrates the course of the nominal value of the relative 80 % of full-scale value.
sensitivity and the limit of the permissible deviation within
the whole frequency range from 1 to 10 000 Hz. These limits of error apply over the whole operating
temperature range authorized for the vibration pickup and
NOTE - In some cases it may be necessary to limit further the
indicator set (see 4.8 and 5.4), for all types of attachments
measuring-frequency range at its upper or lower boundaries to avoid
interfering vibrations which are irrelevant to the assessment of the to the vibration pickup (see clause 4), for all lengths of
vibration characteristics of a machine. For this purpose the connecting cable between the vibration pickup and the
instrument may be equipped with additional high-pass or low-pass indicator provided by the manufacturer (see 4.14) and a
filters. It is recommended that the cutoff frequencies and edge + 10 % fluctuation in the supply voltage.
steepness of these filters be selected in accordance with IEC
specifications. NOTE - Only one of the above parameters shall be checked at a
When the measuring-frequency range is narrowed down by time.
additional filters, the measured value should not be used for
assessing the vibration severity in accordance with IS0 2372 and
3.5 For calibration, the pickup shall be excited by a
IS0 2373. To avoid errors, it is necessary to state the cutoff
frequencies for the measuring-frequency range as well as the sinusoidal vibration with a vibration direction which
measured value, for example arms (40 to 106 Hz) = 7,5 mm/s. deviates by not more than k 5” from that of the sensitive
axis of the pickup. The total harmonic distortion of the
3.3 The selection of the measurement range shall be such exciting vibration velocity shall not exceed 5 %. The
that the indication of the lowest level of the vibration velocity of the exciting vibration must be known with an
iTeh STANDARD PREVIEW
severity to be measured shall be equal to at least 30 % of uncertainty of less than * 3 % within the whole measuring-
frequency range.
the full-scale value. The minimum and maximum levels of
the vibration severity range (for example in accordance (standards.iteh.ai)
with table 1 of IS0 2372) shall be stated, for example It is recommended that the reference value of the
“Measuring instrument for vibration severity with sensitivity at 80 Hz be adjusted to vrmS = 100 mm/s at a
ISO 2954:1975
measurement range 0,28 to 28 mm/s”. room temperature of 20 + 2 “C.
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Reference point
5 1 I WI
of calibration
baIluIaLIuIi

4 , 1
3. I

3 //III I,

. I

1 III II I I I I_,
I I f I I

I“, ‘11 ,, 1
I 1
I 1 1 1 1 I
I
6 I! II

K I 1 I II II 1 1 1 I

100 1,6 2 25 3 4 5 6 8 10' 1,6 2 25 3 4 5 6 8 lo2 1,6 2 2,5 3 4 5 6 8 lo3 1,6 2 2,5 3 4 5 6 8 JO4

Frequency, Hz--b ’

FIGURE 1 - Nominal value of relative sensitivity and limits of permissible deviation

2
 IS0 2954-1975 (E)

4 REQUIREMENTS FOR THE VIBRATION PICKUP 4.7.2 The pickup shall be subjected to a homogeneous
AND CONNECTING CABLE airborne noise field with an rms sound pressure level of
100 dB re 2 X 10B5 Pa in each octave, produced by a
4.1 The pickup shall be of the seismic type, i.e. it shall random noise generator or a warble tone generator over the
measure the vibrations of interest by comparison with a range 32 Hz to 2 kHz.
static reference system determined by the mode of
operation of the pickup. 4.7.3 If the pickup has an electric conducting connection
to the object of measurement and the indicator is line
4.2 If a vibration pickup designed for attachment to the operated, an earth current of 100 mA rms at the supply
object of measurement is used, this shall be affixed by a frequency shall be fed into the earth connection of the
rigid mechanical connection, for example cementing, clamp- pickup and discharge at the earth terminal of the indicator
ing or screwing on or by means of a probe tip. No set.
mechanical resonances of the rigid mechanical attachment
or of the probe tip shall appear in the operating frequency 4.8 The operating temperature range of the vibration
band of the pickup. pickup and connecting cable within which the error of
measurement will not exceed the limiting values specified in
3.4 shall be stated.
4.3 ‘For all types of attachment, the transverse sensitivity
ratio shall be less than 0,l over the whole
measuring-frequency range. 4.9 The permissible temperature range to which the
pickup and connecting cable can be subjected without
The maximum level of vibration velocity for linear response damage shall be stated.
of pickups shall be at least three times the vibration
velocity at full-scale deflection in the sensitive direction. 4.10 The maximum non-operational vibration and shock
limits in any axis of the pickup to which it can be subjected
without damage shall be stated.
iTeh STANDARD PREVIEW
4.4 To show the extent to which the vibration pickup
affects the object of measurement, the effective mass of the
4.11 The maximum humidity to which the pickup and
(standards.iteh.ai)
vibration pickup shall be indicated in an easily visible
manner on the vibration measuring instrument. To suit a connecting cable (as well as supplementary cables which are
wide range of applications, the mass shall be kept to the included) can be exposed and continue to operate within
minimum possible. specification shall be stated.
ISO 2954:1975
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If the pickup is to be used in any other hazardous
NOTE - An indication of whether the mass of the pickup is too
great can be obtained by the following method :
a1c00183171a/iso-2954-1975
environment such as corrosive atmosphere, the ability of
Double the co-vibrating mass of the pickup by an additional mass; if the pickup to withstand this environment shall be
the new indication shows a deviation from the original reading of
indicated. If the pickup is to be used in an explosive
more than 12 %, the mass of the vibration pickup is too great as
compared to the object of measurement and the result should be atmosphere, its intrinsic safety shall be stated.
rejected.
4.12 If applicable, the output of the pickup due to the
4.5 The amplitude and frequency range of the vibration base strain sensitivity at its mounting surface shall be
pickup shall be wide enough to avoid exceeding the indicated.
permissible measurement error, as specified in 3.4.
4.13 If available, information on the predicted mean time
between failures, life expectancy and the recommended
4.6 The pickup shall withstand, without changing its
time between recalibrations of the pickup shall be given.
characteristics, vibration in all directions of at least three
times its specified maximum vibration input.
4.14 If there is a connecting cable between the vibration
pickup and the indicator set, its length shall be at least 1 m.
4.7 The equivalent input quantity of the self-interference The manufacturer shall state what additional extension
by hum and noise and the equivalent input quantity of the cables can be used without exceeding the tolerances in 4.7.
extraneous interference for interference fields and
excitations with a magnitude as stated below shall not
affect the measurement by more than 10 %. When the value 5 REQUIREMENTS FOR THE INDICATOR SET
depends on the orientation of the instrument in the field,
the most unfavourable value shall be used. 5.1 The ind icatin g instrument may be a pointer- tYW
instrumen t, a graph
. recorder or a digi ta I indicator.
The manufacturer shall state the resu Its of tests made u nder
the following disturbing conditions :
5.1.1 The instrument shall indicate the true root-mean-
square vibration velocity.
4.7.1 The pickup shall be subjected to a homogeneous
magnetic field of 100 A/m and 50 or 60 Hz and the field 5.1.2 The error in calibration of the instrument shall not
intensity shall be measured before inserting the pickup. exceed + 2,5 % of the full-scale value.

3
IS0 2954-1975 (E)

5.1.3 The indicator on the instrument shall be easily 5.4 The operating temperature range and non-operating
readable down to l/5 of the full-scale value. To identify the temperatu re range of the indicate r set sh all be stated.
quantity measured and the unit, “II,,, in mm/s” shall be
marked on the instrument.
5.5 The maximum humidity to which the indicator set can
be exposed and continue to operate within specification
5.2 When a sinusoidal signal with a frequency anywhere
shall be stated.
within the measuring-frequency range and an amplitude
permitting a steady-state nominal value of 70 % of the
If the indicator set is to be used in any other hazardous
full-scale value is fed suddenly into the input of the
environment such as a corrosive atmosphere, the ability of
indicator set at an equivalent voltage, the initial overshoot
the indicator set to withstand this environment shall be
shall not be more than 10 % of the final reading. There shall
stated. If the indicator set is to be used in an explosive
be no undershoot at the time when the difference of the
atmosphere, its intrinsic safety shall be stated.
peak values of the pointer oscillations, as compared to the
final position of the pointer, is a maximum of I,5 % of the
full-scale value.

5.3 For the purpose of checking the amplification, there 6 POWER REQUIREMENTS
shall be a device which permits a setting of the total
amplification of the indicator at a specific frequency (for The input power requ i rements for the pickup and indicator
example, 50 Hz) with an uncertainty of less than 4 2 %. set shall be specif ed.

iTeh STANDARD PREVIEW

(standards.iteh.ai)
ISO 2954:1975
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a1c00183171a/iso-2954-1975
 IS0 29544975 (E)

ANNEX

METHOD FOR TESTING rms-VOLTAGE INDICATORS

A.1 TEST Cl RCU IT

True rms meter

Square-wave
s” generator

u=o _ e w

b k
3’

4
I. T.
I
’ I
I T
iTeh STANDARD PREVIEW
(standards.iteh.ai) Sine-wave
generator
ISO 2954:1975 .

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a1c00183171a/iso-2954-1975

Instrument under test

W : network corresponding to
the frequency response of
the instrument under test

F I GU R E 2 - Circuit for the testing of rms-voltage indicators

The following procedure is given as a method suitable for the testing of rms-voltage indicators. The values given below are
based on the following definitions of crest factor :

crest factor = _
6 . . . (1)
u
where

0 is the larger amplitude of the generalized rectangular asymmetrical wave in figure 2 (i.e. c = lu,l or IQ, whichever is
larger);

fi is the root-mean-square value of the wave.

5
IS0 2954-1975 (E)

CREST FACTOR VALUES

By definition,

. . . (2)

For the general case shown in figure 2, it can be shown that

. . . (3)

and that the

crest factor =
0

v (>
. . . (4)
ti
u,2 + (u; -L/Z)
7

Three special cases are

T
A) Symmetrical square wave : up = U, and ti =-
2 >

crest factor = 1 . . . (5)

un and ti
T
B-l) Asymmetrical
iTeh> STANDARD
square wave : up = -
2 > PREVIEW
(standards.iteh.ai)
Jl-
2
crest factor - . . . 6)
4’ 2
ISO 1+
2954:1975 -
( uP >

B-2) Asymmetrical square wave : up < u, and ti

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= -
T
a1c00183171a/iso-2954-1975
2

J-
2
crest factor . . . (7)
2
uP
1+ -
c un >
C) rectangular-pulse wave : (u, = 0 and ti < T)

crest factor =
J ;
T
i
. l .
(8)

A.2 PROCEDURE

A.2.1 Adjust the square-wave generator for ti to be 4 ms. Adjust the period for T of both generators to be 8 ms.

A.2.2 Adjust the sine-wave generator amplitude for a reading on the instrument under test to be approximately 90 % of the
full scale value. Note the reading on the true rms meter.

A.2.3 Switch the circuit to the square-wave generator and adjust the amplitude to give the same indication as in A.2.2 on the
instrument under test. Note the reading on the true rms meter.

A.2.4 Repeat the procedure of A.2.3 while varying the period of T from 8 to 40 ms.

A.2.5 The difference between the true rms readings for A.2.2 and A.2.3 shall not exceed 5 % of the full-scale value related
to the instrument under test for all the values of Tgiven in A.2.4.