REOVIB MFS 268 UL/CSA
Operating Instructions
16
ELEKTRONIK
10.2.6.3 Relationship between acceleration and amplitude
The sensor measures the momentary acceleration of the feeder. It generates a sinusoidal output voltage
signal. The acceleration gets higher as the frequency increases. The sensor signal is greater for a higher
frequency and lower amplitude than for a low frequency with a higher amplitude.
Acceleration
In practice the acceleration is influenced by gravitational force and
the applied amplitude is measured in mm and so this gives the fol-
lowing formula:
[ ]
[ ] [ ]
[ ] [ ]
497
10
2
81
,
9
2
2
2
3
2
2
2
2
mm
s
Hz
f
mm
s
Hz
f
g
a
n
n
=
⋅
=
π
a[g] = Acceleration ( with respect to gravitational acceleration of
9.81 m/s2)
S
n
[mm] = Applied amplitude
In practice where 497 is approximated to 500
this gives, for example:
1.
Vibrating frequency 50Hz
Amplitude 3mm
Or
2.
Vibrating frequency 33Hz Amplitude 5mm
Using an accelerometer with an output signal of 0.3 V/g the sensor generates a peak voltage of 4.5V for a
peak acceleration of 15g (Example 1), corresponding to a 3.18V RMS value.
Example 1:
=> 15 g => 4,5 V => 3,18 Veff.
Example 2:
=> 11 g => 3,3 V => 2,33 Veff.
Because of the vastly different acceleration values of various feeders there is a big difference in the feed
back signals, which makes scaling necessary.
10.2.6.4 Instructions for setting up the controller in regulation mode
Connect control unit
Install sensor and connect to controller
10.2.6.5 Determining the resonant frequency
Manual setting of the vibrating frequency
It is essential that the output frequency is adjusted with the set point set at a low frequency, otherwise on
hitting the resonant frequency it is possible to achieve a high amplitude with a low output voltage. An ana-
log, effective value, current indicating unit (moving iron meter) must be connected into the output circuit.
Resonant frequency is reached when there is a maximum amplitude for a minimum output cur-
rent.
Automatic frequency search
•
The feeder should be empty for a frequency search
•
Adjust the set point to zero
•
Select regulation mode (Menu C 008, Parameter ACC = I )
•
The optimum frequency of the feeder is found, automatically, by initiating the frequency search (Menu
C 008, Parameter A.F.S.). When this has been found the controller resets the set point back to its
original value (0).
f
π
ω
2
=
s
a
2
ω
=
g
a
15
500
3
50
2
=
≈
⋅
=
where
g
a
89
,
10
500
5
33
2
=
≈
⋅
=
