Operation Manual EMGZ490A
30.08.2019
12
4.4
Gain
Depending on the wrap angle of the material on the measuring roller the prevailing
force is not passed one-to-one to the sensors, with the result that the measured
material tension does not correspond to the effective force. In order to account for this
error, the measured force is amplified by multiplier (the Gain). The correction adapts the
measured force with the effective material force. The Gain Factor (V) is calculated with
following formula:
Variables:
F
sys
N=
Installed system force in Newton. This is determined by the number of used
force sensors in the measuring roller. With one force sensor, the system
force is equal to the nominal force mentioned on the label of the sensor. If
the measuring roller contains two sensors the force is twice as large.
F
sys
Digit= System force as a binary value (max. output of A/D-converter). Here it is a
constant with the value 5945. It is independent from the number of used
sensors. From a user perspective, the value corresponds to an input signal of
9mV.
F
ist
N=
Acting force on the measuring system in Newton.
F
ist
Digit= Force measured on the system as binary value (output of A/D-converter).
From a user perspective, the value corresponds to a voltage in mV, that the
amplifier will receive as an input from the force sensors.
Example:
Fsys N = 1000N; Fist N = 500N; Fist mV = 2.25mV (orr 1486)
Note
The mV values in the formula can be replaced by the binary values of the measuring
system (always 5945). The mV value (9 mV) is thus replaced by 5945. The measured
force can be determined using a voltmeter. It replaces the binary value (first digit).
This calculation method is also used by the FMS Calculator tool. Thus it is possible to use the
gain value calculated by the FMS Calculator directly in the calibration. The gain value is then
entered in the parameter set of the amplifier (see chapter 8.2 “Parameter Setting”).
In this
case the calibration procedure described in chapter 4.3 can be skipped. However, FMS
recommends using the traditional method with the weight (chapter 4.2 and 4.3) since it
delivers the most accurate results.
F
sys
Digit * F
ist
N
V =
F
sys
N * F
ist
Digit
9mV * 500N
V =
= 2.000
1000N
*
2.25mV
