The Vibras-7003 is the latest compact and modular system with which all manner of man-made vibrations can be measured, such as from blasting, pile driving, dynamic compaction, machinery, traffic, etc.

The system operates on a principle using microcomputers and is built according to the standard DIN 45669. It consists of the evaluation instrument and the sensors. Up to 12 digital sensors may be connected to a single evaluation instrument. The system enables therefore simultaneous monitoring of vibration at up to 12 independent locations, each in three orthogonal directions, i.e. 36 channels.

The VIBRAS-7003 can also be used for monitoring the levels of noise, which can be performed simultaneously with vibration measurement.

Due to digital transmission of data it is possible to have sensors located at considerable distances from evaluation instrument, (e.g. a single digital sensor can be located at a distance of up to 1500 metres using a standard cable). However, if for a practical reason the cables cannot be accommodated, some or all the sensors can be controlled by a radio signal. Figure 1 is a block diagram of the many connections and interconnections which are possible.

The VIBRAS system is designed for registration of single and/or continuous events. The system is ideal for unattended monitoring of vibration over extended periods of time especially when used with the remote control facility. During monitoring in the ramming or traffic mode the current levels of vibration at each sensor are constantly displayed on LCD. Furthermore, the last 120 events stored in the memory can be reviewed at any time. The clear presentation of measurement data in tabular and/or graphical formats on the printer allows initial analysis on the spot, so that any necessary measures can be implemented immediately.

The Vibras-7003 Vibration Measurement System provides the following:

• Vibrograms of the components along x, y and z axes in terms of the peak particle velocity in mm/s (measurement range between 0.01 and 200 mm/s with a nominal resolution of 0.001 mm/s);
• Vector curve of the maximum sum of the peak particle velocity of x, y & z components;
• Envelope curve, (time-history), of the true peak values of the vector;
• Report of the true peak values of the vector equal to or exceeding a defined maximum level;
• Distribution (%) curve of the true peak values of the vector;
• FFT frequency analysis curve for all three components;
• Adjustable frequency range for the sensors (between 1 and 80Hz, 1 and 315Hz or 4 and 315Hz);
• Envelope curve of the RMS value of each of the three components and their vector sum for a sustained event;
• KB-Values according to the DIN 4150;

The vibration data measured by each sensor is initially stored in a sensor RAM memory, and, if required, it can be subsequently transferred to a hard disk memory of the evaluation instrument and/or a computer. Transfer of data to a computer can be achieved either directly via an RS232 connection or indirectly via a telephone/modem connection. For this purpose, an easy-to-use Window based software for data transmission/remote control is available, i.e. VibModem, which runs under 3.1x, W95/98 or NT. Remote control is functionally equivalent to operating directly with the evaluation instrument. To aid in analysis, evaluation and documentation of the VIBRAS data a Window based software is also available, i.e. VibChart, which runs under W95/98 or NT.

Figures 2 shows a sample of the final print-out, via computer, of vibration data from a vibratory roller.

The above functions together with various trigger modes and alarm facilities make the VIBRAS-7003 an ideal system for monitoring of vibration from a wide range of sources under various conditions. In addition to general measuring purposes, the VIBRAS is a very useful instrumentation for evaluating velocities of wave propagation in the soils or rocks and also for an identification of sources of vibration.

One of the problems with complex digital equipment is that it will soon be outdated. However, the VIBRAS-7003 Vibration Measurement System is constructed on an open architecture computer concept, which permits staying in step with future developments. The instrument continues to be adaptable to the latest standards or requirements.

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FIGURE 1: VIBRAS-7003 VIBRATION MEASUREMENTS SYSTEM
WITH DIGITAL SENSORS AND A NOISE METER