Measuring Slow Rotating Objects; Using The Max/Min/Ave Function - Omega OMEGAETTE HHT-1500 User Manual

3.8. Measuring Slow Rotating Objects

If the rotating speed of the object which you are measuring is very
slow, it is recommended that you use a tripod to hold the tachometer
in place and use multiple pieces of tape for more accurate result.
If multiple pieces of tape are used, each piece of tape should be
located at a equal distance to each other on the object. Any number
of pieces of tape are acceptable. But you need to divide the reading
by the number of pieces to obtain the correct result.
Correct RPM = Reading / (number of pieces of tape)
Example: 4 pieces of tape and reading is 12 RPM.
Correct Speed = 12 / 4 = 3 rpm
3.9. Using the MAX/MIN/AVE Functions
These functions allow users to analyze the stability of rotational
speed. These value are actually peak (MAX), valley(MIN), and true
average(AVE) values.
MAX: Press the function button to select maximum function. The
MAX function can be used to find the peak value of speeds
measured.
MIN: Press the function button to select minimum function. The MIN
function can be used to find the valley value of speeds measured.
AVE: Press the function button to select average function. The
average function is a true average value.
1
å rpm)
RPM =
AVE n
If summation of average value overflow, or n > 65535, the last
average RPM will be used as initial value for successive calculation.
And n will be reset to 1.
When users press the HOLD button (same as START button), the
max/min/ave values are still stored in memory. Users can press the
function button (right button) to review the values. To return to
normal mode, press and hold the function (right button) for 2
32
; å rpm) < 2 , n < 65535
n
11
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