Notes On Speed Measurements - Extech Instruments 461830 User Manual

1.800.561.8187

Notes on Speed Measurements

Care must be taken to ensure that the mark is providing a 1:1 measurement. Check that there is
only one mark and not two, four, or more stationary marks on the object under test.
instrument will display double, triple, or quadruple the actual speed. A useful method of avoiding
harmonic measurements is to adjust the FINE/COARSE knobs until two images (marks) appear and
then lower the flash rate (via COARSE/FINE knobs) until a single, stationary image appears. This
will be the actual speed.
In the example below, a rotating shaft is affixed with one piece of tape. The illustrations below
represent several possible images that would appear when the strobe beam is pointed to the shaft.
If more than one mark appears (as i
The bold column (column 2) shows the actual speed of the shaft. Column 1 shows a harmonic
Shaft speed 1000rpm
Strobe flash rate 500rpm
Visible marks 1
Note that the LED display has an AUTO RANGE INDICATOR (flashing decimal at the far right) that
appears when the readings are over 10,000 RPM. In these cases, multiply the displayed reading by
10.
Copyright © 2013-2018 FLIR Systems, Inc.
All rights reserved including the right of reproduction in whole or in part in any form
www.
-between (Column 2 in bold).
1000rpm 1000rpm 1000rpm
1000rpm 2000rpm 3000rpm
1 2
.com
1000rpm
4000rpm
3 4
information@itm.com