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4.2. Switching on and Connecting the Sensor

Switch on the VM31 by pressing the ON/OFF key. The
unit can be switched off again by pressing and holding
the ON/OFF key for one second.
If the sensor has not yet been connected, plug the sensor
cable   into   the   right   connector.   The   VM31   will   start
TEDS

1

 detection each time it is switched on or a sensor is

connected. It supports IEEE 1451.4 TEDS template no.
25 (with or without transfer function). The sensitivities of
X/Y/Z   and   channel   A   are   displayed   for   some   seconds
(Figure  3). For each channel also the user text of TEDS
(ID) is displayed.

The sensors KB103SVD and KS903.10 supplied by Metra feature TEDS.
Should a connected sensor not have TEDS or an incompatible TEDS version, the
VM31 will open a menu for entering the sensitivities manually (see section 10.1). 
The sensitivities entered remain stored as long as the sensor is connected, even if the
batteries are removed.
The warning “SENSOR!” indicates a missing or defective sensor or a broken sensor
cable. Sensor condition is detected by means of the bias voltage at the sensor out -
put: 
< 0.7 V: 

short circuit

0,7 – 14 V:

normal

>14 V:

open, e.g. broken cable

Please note that settling time after connecting a sensor is
about 1 minute.
The VM31 is suitable for connecting any low power IEPE
accelerometers which can be operated with a 1 mA supply
current.   The   internal   compliance   voltage   of   the   current
sources is 18 VDC. 

1 TEDS = Transducer Electronic Data Sheet

8

Figure 3: 
TEDS detection

Figure 4: Seat pad accelerometer KB103SVD

Figure 5: 
Hand-Arm accelerometer KS903.10

Figure 6: 
Sensor socket 
(view from outside)

GND

X

Y

Z

Содержание VM31

Страница 1: ...ed Weber Metra Mess und Frequenztechnik in Radebeul e K Meissner Str 58 D 01445 Radebeul Tel 49 351 836 2191 Fax 49 351 836 2940 Email Info MMF de Internet www MMF de Human Vibration Analyzer VM31 Val...

Страница 2: ...Fax 49 351 836 2940 Email Info MMF de Internet www MMF de Note The latest version of this manual can be found at http www mmf de prod uct_literature htm Specification subject to change 2014 Manfred W...

Страница 3: ...with VDV Values 18 4 4 2 3 Seat Effective Amplitude Transmissibility SEAT 18 5 General Vibration Measurement 19 6 Data Logger 21 7 Frequency Analysis 22 8 Data Memory 23 8 1 Measurement Data Memory 23...

Страница 4: ...2631 and the EU Directive 2002 44 EC A fourth measuring channel can be used for example for SEAT mea surements seat effective acceleration transmissibility The VM31 meets the requirements for human vi...

Страница 5: ...on of human exposure to hand transmitted vibration ISO 2631 Evaluation of human exposure to whole body vibration also ASA ANSI S3 18 ISO 8041 Human response to vibration Measuring Instrumentation ISO...

Страница 6: ...oducing the least possible vibration Provision of auxiliary equipment that reduces the risk of injuries such as protec tive gloves or special seats Appropriate maintenance programs for work equipment...

Страница 7: ...ral partial exposures with different vibration magnitudes This can be the case if there are longer interruptions in the work process if the work equipment or its way of use is changed A partial exposu...

Страница 8: ...e are based on RMS values An alternative method uses fourth power mean values called Vibration Dose Value VDV with the mea suring unit m s1 75 Table 1 also includes VDV based limit values VDV based da...

Страница 9: ...moving the batteries To insert the batteries remove the two screws from the back cover of the device and open the battery compart ment Figure 2 When inserting the batteries please en sure that their p...

Страница 10: ...ble TEDS version the VM31 will open a menu for entering the sensitivities manually see section 10 1 The sensitivities entered remain stored as long as the sensor is connected even if the batteries are...

Страница 11: ...performed with the same hand pressure force as used under normal operating conditions Since most machine tool handles do not provide surfaces for the adhesive or screw attachment of sensors Metra off...

Страница 12: ...RMS Maximum Transient Vi bration Value MTVV which may indicate the pres ence of shock vibration The frequency weighting for hand arm vibration is Wh Figure 11 shows the filter of the VM31 and the tol...

Страница 13: ...sing samples An overload event during the entire averaging time is indicated by OVL in the upper right corner after the date This warning can be deleted by pressing the key Reset After measurement you...

Страница 14: ...lt into a flat rubber pad which adapt themselves to the interface between the vibration source and the test person Figure 4 The following measuring points are suitable On the seat surface under a seat...

Страница 15: ...ll always be in a vertical po sition with Z perpendicularly to the backbone However to compensate this the VM31 auto matically swaps the X and Z axis for backrest measurement 4 4 2 VM31 Settings 4 4 2...

Страница 16: ...other postures sensor positions and differ ent frequency weightings but the general procedure is the same Figures 17 to 20 show the frequency response curves of the weighting filters for comfort measu...

Страница 17: ...ger trains 0 1 1 10 100 1000 0 0001 0 001 0 01 0 1 1 10 Wb min ISO 8041 Wb max ISO 8041 Wb VM31 Hz Figure 18 Whole body weighting filter Wc for the backrest of seats 0 1 1 10 100 1000 0 0001 0 001 0 0...

Страница 18: ...evaluation can be the running RMS method MTVV or the fourth power vibration dose method VDV whereupon the latter is more common One of the two additional evaluation methods should be applied for occas...

Страница 19: ...et to 1 for maximum RMS MTVV and vibration dose value VDV OVERLOAD is indicated instead of the measuring values if the current magni tude is too high Even if the overload condition was of short durati...

Страница 20: ...g the key Reset Measurements can be saved by pressing the key see page 17 For vibration exposure VDV 8 calculation the duration of VDV measurement should be noted see section 3 2 The Excel file vm31 x...

Страница 21: ...ssing the key Please note that the RMS and peak values in the general vibration ranges are mea sured over the last display cycle not over a long period A display cycle can be between 1 and 4 seconds d...

Страница 22: ...lacement Low frequencies including noise are strongly amplified High pass filtering is inevitable The frequency response curves of the general vibration ranges can be seen in Figures 27 28 and 29 20 F...

Страница 23: ...he Excel file vm31 xlsm can be used to transfer the measurements to a PC 6 Data Logger The VM31 can automatically record measuring data for channels X Y Z at the speed of the display re fresh rate It...

Страница 24: ...r will be halted while data is transferred via the USB interface This may result in missing records The automatic shut off function see chapter 10 3 is not in use while logging The maximum number of r...

Страница 25: ...nt data can be transferred to a PC using the Excel macro file vm31 xlsm 8 2 Logger Data Memory To view stored logger data press F3 to open the menu and select Data memory Data logger In this menu open...

Страница 26: ...check or to change the entered sensitivities Sensitivities are entered one after another for chan nels X Y Z and if connected for channel A The sensitivity value is a five digit number with the measu...

Страница 27: ...ypes To select the battery open the main menu by pressing F3 select Device settings and Battery type Within the sub menu select Battery type Figure 40 pressing selects between Alkaline non rechargeabl...

Страница 28: ...PC The VM31 has a USB interface The VM2x USB cable Figure 44 is connected to the VM31 via its 8 pin connector Switch the device off before connecting it to the PC Connect the other end of the cable t...

Страница 29: ...8 can be calculated from the human vibration records and measuring reports can be generated FFT data can also be transferred and displayed graphically To work with the file you need to allow macro ex...

Страница 30: ...tion Exposure A 8 and VDV 8 Vibration exposure A 8 and alternatively VDV 8 are both used for the risk as sessment of human vibration They can be calculated based on hand arm H A and whole body measure...

Страница 31: ...ctivity Below you will find the vi bration exposure results for each person Figure 48 13 4 FFT Data Import to Excel The FFT data stored on the VM31 can also be transferred to the Excel macro file Swit...

Страница 32: ...on the start screen Figure 50 If a Firmware version with a higher number is available on the website proceed as follows 1 Download the firmware file vm31 hex from the above named internet address 2 Al...

Страница 33: ...Figure 52 Figure 52 Firmware update 7 Click on Send in the Firmware Updater Transfer of the Firmware data has now begun The transfer progress is displayed as a time bar on the PC and also on the VM31...

Страница 34: ...erator needs to be connected via the shown R C combination to the inputs X Y Z and A The 4 7 k resistor serves as a sink for the IEPE constant cur rents The 1000 F capacitor keeps the resulting DC vol...

Страница 35: ...mV ms 2 0 01 m s 0 1 mm s 1 m Sensor with 100 mV ms 2 0 001 m s 0 001 mm s 0 1 m Linearity range 75 dB for 6 error Noise 0 003 m s Filters Human vibration Acceleration Velocity Displacement Weighting...

Страница 36: ...er this warranty does not apply to any improper or inadequate maintenance or modification and operation outside the product s specifications Shipment to Metra will be paid by the customer The repaired...

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