Chauvin Arnoux C.A 25 Mode D'emploi page 51

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For measurement without contact :
Before using the tachometer check that the front sighting window is perfectly clean.
The minimum detection distance is 1 cm, nevertheless avoid immediate proximity
of any moving part which could be dangerous for the user or the instrument.
For measurement with contact :
Keep your hands as far as possible from the moving part. Do not apply excessive
force to the instrument particularly when using the wheel because the measurement
may be falsified by braking the moving part.
For measurements at the end of a shaft, position yourself as closely as possible to
the axis of the shaft.
For measurements with an external input :
Follow the precautions applicable for connections between counting instruments
when using the external socket, to eliminate industrial interference. Use screened
wires connected to a ground that doesn't receive switching rejects from power
systems.
The interference received mustn't exceed the amplitude of the hysteresis set for the
instrument (250 mV).
The external input is limited to a maximum common mode of 50 volts.
WARNING :
the electrical ground of the external sensor socket is common to the
electrical ground of the digital RS 232 output.
In all cases :
Never immerse the instrument in water.
Never spray cleaning agent or alcool on the instrument or its accessories. If this
happens, wait for the instrument to dry without wiping.
SAFETY PRECAUTIONS
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