SlimLine 9173B, Инструкция по эксплуатации

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SlimLine Force Sensor, Type 9173B to 9177B
Page 18 9173B_002-286e-07.10
5.4 Quasistatic Measurements
Purely static measurements over any length of time are not
possible with the piezoelectric measurement principle. As
the charge amplifier is not an ideal component, the charge
stored on the range capacitor is not retained indefinitely.
Leakage currents product a drift of the order of ±0,05
pC/s. During measurement the zero of the output signal
shifts in the positive or negative direction as a function of
time. With the sensor under no-load or constant load con-
ditions, this can be measured with the charge amplifier in
the <Operate> or <Measure> mode.
Pronounced drift allows the conclusion that the insulation
resistance of the measuring chain is insufficient. It is there-
fore important to keep cables and connectors clean and
dry.
The period of time over which so-called "quasistatic"
measurements can be performed is determined by the re-
quired accuracy . With the value of the sensitivity of the
sensor (for example, SlimLine quartz force link Type 9173B:
–3,5 pC/N), the drift can be estimated in mechanical units:
For the example of a SlimLine quartz force link Type 9173B
and a ControlMonitor Type 5863A1, the following me-
chanical drift results:
Sensitivity –3,5
pC/N
Drift ±0,1 pC/s
mN/s 1
pC/N 3,5 –
pC/s 0,05
43 ,
 

mN/s 86 , 2
pC/N 3,5 –
pC/s ,1 0
 
