MMF VM24, Инструкция по эксплуатации

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2.2. The Measuring Instrument
2 shows the block diagram. The VM24 supplies the IEPE Sensor with 2 mA con-
stant current. At the sensor output, a vibration acceleration proportional AC voltage
arises, which is amplified in the instrument to produce an optimum level. The gain
switch-over takes place automatically. The subsequent analogue/digital converter is
a Sigma-Delta converter with 24 bit resolution.
Further signal processing, such as filtering, integration (for calculating velocity and
displacement from acceleration) as well as the RMS and peak value rectification is
carried out in the micro controller. The micro controller also controls the graphic
display, the USB communication and the storing of measurements.
3. Measuring Ranges
3.1. Measurable Vibration Quantities
The VM24 can display the vibration quantities acceleration, velocity and displace-
ment. Velocity and displacement are generated by single or double integration of
the sensor acceleration signal.
Furthermore, various frequency ranges can be selected.
The display rate adjusts itself according to the selected quantity in order to ensure
that the RMS does not fluctuate even at lower frequencies. The following table
shows the display rates.
4
Figure 2: Block Diagram
IEPE
supply
Progr.
amplifier
A
D
Micro
controller
Display
Memory
Keys
Sensor
ID
USB
Power
supply