OHAUS Defender D100HL, Руководство по обслуживанию

Страница: 13 / 36

CHAPTER 1 INTRODUCTION
1.8 HOW LOAD CELLS OPERATE
The difference in the output signal before and after the mass was placed on the platform is
taken, interpreted and displayed.
Figure 1-3. Route of electrical Load Cell input and output through Wheatstone Bridge circuit.
A Load Cell is a force sensor, which receives a voltage (excitation) from a regulated power
source in the Indicator, and sends back a low-voltage milli-volt (mV) relative to the force applied.
The Load Cell signal is read by the Indicator, which converts it to a numeric value and shows it
visually. This output value increases as weight is loaded to the Load Cell.
For example, a 500kg Load Cell with 2mV/V output and 5V excitation would have a change of
0.02mV per kg change in the load, that is, 10mV/500=0.02mV per kg. At a load of 250kg the
signal voltage would thus increase by 5mV from the value measured at no load.
Tension
Tension
Compression
Compression
+Excitation
(Supply)
–
Excitation
(Supply)
INPUT(volts)
LOADCELL
2 mV/V
Strain
Gauges
4 strain gauges
connected as a
Wheatstone
Bridge
OUTPUT (milli volts)
+ Sig
–
Sig
Defender™ H-Q-W Series Service Manual 1-7 Ohaus Corporation www.ohaus.com