AN Measuring vibration - Norl40

Product catalog summary

Introduction
This document outlines the use of the Nor140 sound level meter for measuring vibration through acceleration levels. It explains the substitution of the microphone with an accelerometer and covers calibration and the conversion between decibel levels and linear acceleration units.

Accelerometer Types
The document focuses on accelerometers, particularly the ICP® or CCP types, which are commonly used for vibration measurement. These transducers have low output impedance and are powered by a constant current. The Nor1270 and Nor1271 models are recommended for use with the Nor140 sound level meter.

Connection Setup
For ICP® or CCP accelerometers, connect using the BNC/Lemo cable Nor1438 and the BNC to microdot adaptor Nor1466. For charge-sensitive accelerometers, use the Nor1209 preamplifier and the Nor1447/2 adapter. Calibration is more complex for charge-sensitive types due to high impedance and cable sensitivity.

Levels and Linear Units
Sound pressure levels are typically measured in decibels (dB), with a reference value of 20 μPa. For acceleration, the reference is 20 μm/s². Conversion from dB to linear units can be done using specific equations, and the Nor140 can display results in linear units by selecting engineering units in the setup menu.

Calibration
Calibration requires a vibration calibrator with a known acceleration level. The Nor140 can be adjusted to display the correct level, similar to microphone calibration. Frequency considerations are important during calibration to ensure accuracy.

Velocity and Displacement
Vibration can also be measured as velocity or displacement, derived from acceleration through integration. The Nor140 does not perform integration, but calculations can be done using frequency data.

Frequency Weighted Acceleration
ISO 8041 specifies different frequency weightings for assessing vibration severity. Weighted acceleration values can be calculated from 1/3-octave band levels using specified weighting factors.

Conclusion
This document provides detailed guidance on using the Nor140 sound level meter for vibration measurement, including setup, calibration, and data interpretation.

Catalog excerpts

Application Noie Measuring vibration using sound level meter Nor140 This technical note describes the use of the sound level meter Nor140 for measurement of acclration levels. The normal microphone is then substituted by an accelerometer. The note also describes calibration and the relation between the level in d驩cibel and the acclration in linear units. WNorsonic

Open the catalog to page 1

tH Norsonic Introduction Most sound level meters and sound analysers can be used for vibration measuremenls, even If they do not provide absolute (linear) unils in the display, To simplity the description, ths application note describes the use of the handheld sound level meter Norsonic Nor140. However, the described principes also appty to other types of sound level meters. Ailhough several transducer princ魮ples are commercial availabie. this application note will deai with tho accoioromcter only, simply because it is the transducer type most commonly encountered when measuring vibration feveis....

Open the catalog to page 2

M Virant» Fd?0<tv EngWl 03 OR hNNorson/c Norl40 Mor1209 Preamp. Nor1447/2 Nor1466 I Microdot. cable [Normally supplied wth accelrometer) Accoioro motor Set-up for using a charge-sensitipe type ofacxelerometer connected to NorldO* The chargeproduced by the acveterometergn멩rtes a voilageproportionat to the inverse ofthe capacitance loadtng the charge generator The capaeitante the sum ofthe capacitartce for the accelerometer and ail table* connectedto the transducer. The microphone prearnplifterw normally Norl209* has very high tnput imp⹩dance - typualfy 10gtgaohm andan tnputcapacitancebelow l pF...

Open the catalog to page 3

AN Vibration Ed2Rev0 English 03.08 P.O.Box 24, N-3421 Lierskogen, Norway Tel.: +47 3285 8900 Fax.: +47 3285 2208 [email protected] www.norsonic.com Distributor: ICP-type If you use an ICP-type of accelerometer with a known sensitivity, it is easy to calculate the required sensitivity setting for the instrument. Just enter the sensitivity for the accelerometer in volt per unit as a level-sensitivity in dB. Example: Assume the sensitivity for the accelerometer is 2,5 mV/ms-2. The level-sensitivity is therefore: By entering this value as sensitivity in the calibration menu, the instrument is calibrated...

Open the catalog to page 4

AN Measuring vibration - Norl40

AN Measuring vibration - Norl40

Catalog excerpts

All Norsonic AS catalogs and technical brochures