Transcript
URWHF DSM - TORSIONAL VIBRATIONS IN REAL TIME REAL TIME DIGITAL PROCESSING OF DYNAMIC ROTATIONAL SPEED SIGNALS The DSM unit from rotec is designed for digital processing of rotational speed signals. The speed of a rotating shaft is measured by scanning a toothed wheel with a proximity sensor or by fitting a rotary encoder to the shaft. The DSM outputs, in real-time, two independent 16-bit analogue voltage signals which are proportional to the input TTL pulse train signal. The DSM’s dynamic frequency response and high resolution allow measurements over the complete range of shaft speeds. The unit is designed in Euro-format (3U) for 19" racks and can be plugged into the backplane for access to the +5V/2A supply required (standard DIN connector). All connectors for input and output signals are located on the front panel.
Measurement principle The angular velocity signal must be provided by a sensor which detects at constant angular intervals around the rotating shaft. This may be accomplished by scanning a toothed wheel with a proximity sensor or by employing a rotary encoder fitted to the shaft. A signal conditioning unit is required which converts the sinusoidal sensor output signal to a square wave TTL pulse train. The periodic times of the input pulse train are measured with the aid of a 100 MHz, 32-bit counter/timer circuit. The DSM also contains a fast, digital signal processor. The program for this processor is stored on EPROM. Input parameters are provided from a computer via RS-232 port. The settings to be
made are the number of teeth of the target wheel (or encoder line-count), the analysis which is to be carried out, the scaling of output voltage signals and the cutoff order of a low pass digital filter. This filter is used to separate the steady and fluctuating components of the input signal. The two output channels carry voltages which are proportional to the results of the analysis which has been performed. Both channels may be independently scaled in the range -10V to +10V. The following analyses are available: (i) average speed [rpm], speed fluctuation in [rpm]. (ii) average angular velocity, fluctuation in angular velocity, both in 2 [rad/s] or [deg/s]. (iii) angular acceleration in [rad/s ] 2 or [grad/s ], average speed in [1/min].
Key Features: •
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1 input for TTL-level signals 0.023 Hz to 390 kHz, 32-bit, 10 ns counter/timer 2 analogue outputs ±10V, both 16-bit. Supply voltage for rotec gear-tooth sensors and Heidenhain encoders 6 Line count from 1 to 10 Divider for line count Operating voltage: +5V (2A)
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URWHF GmbH
Joseph-Dollinger-Bogen 18 80807 Munich Phone: +49 89 3236510 Fax: +49 89 32365156
Germany
