Operation; Measurements Without Contact - Chauvin Arnoux C.A 25 Mode D'emploi

OPERATION

MEASUREMENTS WITHOUT CONTACT

Measurements that are taken without contact are done with the optical sensor
integrated in the instrument. This sensor, located in the front end of the instrument,
consists of a frequency modulated infrared light emitter. The infrared receiver is set
at the same modulation frequency. This device makes it possible to overcome
interference signals due to lighting conditions.
Before any measurement, it is necessary to prepare the rotating target whose
speed is to be measured.
Check that the targeted surface doesn't emit interference reflections which could
be counted in addition to pulses output from the reflective scotch tape.
To do this, before sticking on the scotch which will be used for the measurement,
turn the target and check by sighting it that the measurement is zero. If not, cover
the entire surface of the target with a black matt scotch.
When the target is correct, stick a strip of reflective scotch onto it along the axis of
a beam, as long as possible. For small targets the surface covered by the scotch
must be less than 50% of the total surface of the rotating part.
Rotate the target, sight it with the front part of the instrument, check that the correct
measurement symbol on the display is flashing regularly.
The distance between the sensor and the target must be between 1 and 50 cm.
The measurement cone of 30° (15° either side of the axis of the instrument) allows
easy sighting.
When measuring low speeds, trembling of the hand holding the instrument can
result in instabilities of this measurement, in this case, we recommend that you set
the instrument on a stable support near the target. A nut located under the
instrument is provided so that it can be mounted on a stand.
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