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Technical data are subject to change without notice.
ISO 9001 certified. © Copyright SPM 1996-9. 71416.B
SPM Instrument AB • Box 4 • S-645 21 Strängnäs • Sweden
Tel +46 152 22500 • Fax +46 152 15075 • info@spminstrument.se • www.spminstrument.se
Optical Measurement of Rotational Speed
In Manual mode, the A2011 can be used for optical
measurement of rpm and for contact measurement of
both rpm and peripheral speed. The measuring range
for optical measurement is 10 to 19 999 rpm. The
maximum speed for contact measurements is lower;
it depends on the operator’s ability to hold the tacho-
meter probe steadily against the moving shaft or
wheel.
The A2011 switches automatically to the tachometer
mode when the tachometer probe is connected. This
can be done without disconnecting the SPM or VIB
transducers. The last speed reading is shown on the
screen when the A2011 is switched on (figure 27).
While the M key is held down, the A2011 counts the
light pulses which are reflected back into the tacho-
meter probe, either from a reflecting tape attached
to the object or from the reflecting tape inside the
contact adapter. The peak indicator blinks when a
light pulse is received. The instrument needs at least
two light pulses within 6 seconds to give a reading.
Reflecting Tape
Optical readings can be taken from a distance of max.
0.6 m and from an angle of max. 45°. Clean a suitable
spot on the shaft and attach a square of reflecting
tape (SPM TAD-14 or TAD-16). Note: the tape must
not reach more than half way around the shaft.
Optical Measurement of rpm
For optical readings, the tachometer probe is used
without the contact adapter.
• Press and hold down the M key. Direct the light
beam towards the reflecting tape.
• Watch the peak indicator. It blinks when the light
beam is on target.
• Hold the instrument steady until the new rpm is
shown on the screen, then release the M key
before moving the instrument.
TACHOMETER
3650 rpm
Speed reading
Fig. 27
Fig. 29
Fig. 28
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