Current Output; Measuring Range; Adjustment - HBM MC3 Bedienungsanleitung

MC3

4.2 Current output

In operations with current output, a balance should be carried out as de-
scribed under "voltage output". The zero signal remains stable when switching
from current to voltage output. Each time the measuring range is switched,
the zero signal must be balanced again.

4.3 Measuring range

The MC3 measuring amplifier is provided with two switchable measuring ran-
ges as standard. The MC3 is set to measuring range " 0.2 mV/V at the fac-
tory (S 21, circle not visible). This setting enables a measuring range between
0.2 mV/V and 2 mV/V to be selected by unsoldering resistor R44 (R44/1;
R44/2) and soldering in a resistor R44 to be computed (see following formula).
The resistance value for R 44 as a function of the desired measuring range
may be obtained from:
2 · 27.4kOhm
R44 +
Measuring range A in mV/V
The resistor should have a temperature coefficient TK of < 50 ppm. In addi-
tion, a maximum measuring range fine adjustment of 40 % referred to the full
scale deflection set can be carried out with screwdrivertype potentiometer
P 23.
The second measuring range is set at " 2 mV/V (switch S 21, circle visible)
at the works and cannot be changed.

4.4 Adjustment

Measuring amplifier MC3 can be adjusted either with an electrical signal from
a calibration equipment or with a defined transducer output signal.
After zero balance a defined signal should be applied to the measuring signal
input of the MC3 (terminals 21/1 and 21/4) using on HBM calibration equip-
ment, or a connected transducer should be detuned mechanically by a given
amount. The corresponding output voltage should then be set with the fine
range adjustment (P 23) using the ratio 0.2 mV/V or 2 mV/V. The resistance of
the calibration equipment and the transducer to be connected should be the
same.
A1705−3.2 en/de/fr
A
15
HBM