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No rotational pulse signal is required for a measurement. The rotational speed is
calculated from the frequency signal of light, magnetism, vibration, and sound.
The FT-2500 is an advanced tachometer which measures the rotational speed by the Fast Fourier Transform (FFT)
calculation. Moreover, the FT-2500 can measure the rotational speed from frequency signal of sound, vibration or the
like even though the rotating shaft is not accessible. The FT-2500 allows versatile rotational speed measurements such
as the steady rotation of motor and acceleration/deceleration rotational speed of engine.
Features
•
The reflective marks or special machining is not needed to
attach the sensor.
•
Because the rotational speed measurement can be
performed easily from the frequency signal of sound or
vibration, no special machining to rotating shaft is
required.
•
The measurement under the condition of the change or
acceleration/deceleration in the rotational speed is
available. (When the acceleration/deceleration rotation
measurement mode is selected.)
•
Provides rotating direction determination function. (When
the FT-0501 DC Motor Rotation Detector is used.)
•
Easy to read fluorescent display.
•
Provides both the analog and pulse outputs.
•
Ethernet communication function can be added as an
option.
Front
Level monitor LED
This LED is used to monitor the
sensor's input signal level.
LED colors
Signal level
Green
Appropriate signal level
Red
Signal level is too high.
Unlit
Signal level is too low.
Comparator status display LEDs
LEDs for displaying comparator operation
status of UPPER, LOWER or ROTATION.
LED colors
Comparator status
Green
Comparator OFF
Red
Comparator ON
Unlit
Comparator disabled
< COMP > key
Key for starting/stopping the comparator function. When
comparator function of automatic ON is set at 'Normal' , the
comparator function will be OFF at the time of restarting the
main unit. If comparator function of automatic ON is set at
'Auto' , the comparator function will be held its state at the
time of restarting of main unit.
< SENS > key
Key for fine adjustment of the sensor sensitivity. Pressing
this key displays the sensitivity level. Press [ ] or [ ] key
to make fine adjustment of the sensitivity.
< MENU > key
Key to select measurement mode or setup mode.
< SET/NEXT > key
In setup mode, you can go to the next setup item by pressing
this key. Pressing and holding (for approximately 2 seconds)
this key make the key protection function start or stop.
2
Previous or conventional model
Previous or conventional model
Advanced Tachometer FT-2500
UPPER
LEVEL
SET
COMP
SENS
MENU
LOWER
NEXT
KEY PROTECT
ROTATION
When the amplitude of rotational signal
is not stable and some of the pulse
signals cannot be detected, the
t
rotational speed is calculated lower than
it should be.
When the electrical noise is contained in
the rotational signal, the rotational
speed is calculated higher than it should
t
be owing to the malfunction by noise.
Model FT-2500
Model FT-2500
Measurement using FFT
technology is not affected by
noise and irregular signal
amplitude.
Displaying section
It displays the measurement value.
Displaying item can be selected from
rotational speed (r/min) or frequency
(Hz) in setup mode.
<
In setup mode, use this key to change
the setup value or selected item.
SAMPLE
RECALL
<
In setup mode, the position of the digit
for inputting the condition can be
moved by pressing this key.
In acceleration/deceleration rotation
measurement mode, it is used for
measurement start or selection of
rotational peak.
Algorithm
Algorithm
Selectable contents vary depending on the rotational condition. There are 5 kinds of measurement algorithms.
MODE
A
Steady rotation
B
measurement mode
C
Acceleration/deceleration
D
rotation measurement
mode
E
• In C,D, and E mode, the FT-2500 follows up the acceleration/deceleration condition owing to the
internal high speed processing function.
• In C mode, the FT-2500 predicts the peak value which it should be and calculates the rotational
speed even if the maximum peak has been lost.
• In E mode of rotational speed candidate selection, suitable rotational speed can be selected
from maximum of 8 frequency peaks.
Calculation is performed using the
The frequency intervals of the each order component in the
frequency of the power spectrum's
rotation are sought sequentially. The most often appeared
maximum peak. Measurement is
frequency interval is judged to be the first-order component of the
usually performed in this mode.
rotational speed in order to fix the rotational speed. This is an
effective method when the first-order peak is unstable.
1st order signal
component
Frequency (Hz)
Maximum power spectrum peak
detection method
Analog output waveform
r/min
Fluctuated display values
Analog output waveform
r/min
Stable display values
/
> key
/SAMPLE> key
Measurement algorithm
Maximum power spectrum peak detection method
Peak-interval mode method
Multi-order peak followup method
Maximum power spectrum peak followup method
Specific power spectrum peak followup method
Rotational speed candidate selection function
2nd order signal
3rd order signal
component
component
Noise component
Frequency (Hz)
Frequency interval = rotational basic order
Peak-interval mode method
t
t
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