Operating Mode
The DMA2 is a strain gauge amplifier processes sensor signals in the analog mode. The parameter values,
however, are digitally adjusted. LEDs indicate the operating status. The digital display shows the parameter
value respectively the output signal.
Adjustment Modes
Zero adjust calibration
- either automatically by key operation (details: see page 6)
- or manual: moving the zero point by the amount of the web weight on
the measuring/idler roll
The second possibility is useful if e.g. the web tension control system is preloaded with the defined web
weight either while in operation or at standstill. Another application can be e.g. a silo which cannot be
completely emptied and has a certain amount of weight remaining.
Amplification parameter defined by a value (gain)
In this case the gain is calculated and correspondingly adjusted
Example
Sensor data:
nominal rating 1,5 m V/V
bridge supply voltage: 10 V
(the output signal is therefore 15 mV = 0.015 V at nominal force)
Amplifier output: 10 V at nominal web tension
0 V at zero web tension
If the sensor is operating below its nominal force then the amplification must be increased.
Example
The maximum sensor load is only 75% of nominal force.
The output signal is therefore only:
this leads to:
Amplification adjustment with calibration weights
In this operating modes the web tension measurement equipment is loaded with calibration weights
and the amplification is adjusted accordingly. This is the more realistic but more cumbersome method.
page 2
HAEHNE
Elektronische Messgeräte GmbH · Heinrich-Hertz-Str. 29 · D-40699 Erkrath Germany · Telefon 0211/9 25 91-0 · Fax 0211/9 25 91-20
http://www.haehne.de
Email: [email protected]
HAEHNE
15 mV • 75 % = 11,25 mV
100 %
Gain =
10V = 888,88 ≈ 888,9
0,01125 V
Gain =
10V = 666,66 ≈ 666,7
0,015 V
The selected sequence of the adjustment steps is based on experience in practice situations.
Other sequences of adjustment steps are certainly possible.
08.08 DE1DM2EA.indd