Showa 5683, Руководство по эксплуатации

Страница: 43 / 68

４−９
(2) Where a voltage divider is required
If the input level of a data recorder is +/-1 V, a voltage divider is required. Pay due care to the
impedance.
In general, since the output impedance increases as the frequency band becomes higher, it is
expressed as:
Ｒ
0
（
Ω
）
+
Ｌ
0
（
µ
H
）
.
If a voltage divider is inserted as shown in Fig. 4-6, this will cause errors, as described in the
following example.
Example:
Errors will be caused as shown in Table 4-5, if the voltage dividing ratio is 1/10 under the
following conditions:
Input impedance of data recorder:
Ｒｉ
=100
ｋ
Ω
,
Ｃｉ
=100
ｐＦ
Output impedance of the amplifier unit:
Ｒ
0
=
１
Ω
,
Ｌ
0
=200
µ
Error due to Voltage Dividing Circuit (%) Ｒ
1
(k
Ω
)
Ｒ
2
(k
Ω
)
DC
１
kHz
２
kHz
５
kHz
１０
kHz
90 11.1 -0.08 -0.08 -0.09 -0.12 -0.24
9
1.01 -0.02 0.02 -0.02 -0.02 -0.02
Table4-5 Error due to Voltage Dividing Circuit
4.4 How to Read Measured Values
This section describes how to read the measured values of a waveform recorded on a data
acquisition device or recorder.
Fig.4-7
Measured value at point B={ } x Set CAL value
(1) Measurement with strain gauges
Set CAL value: 500
µ
ε )
Deflection of CAL waveform: 10 mm
Deflection at point B: 22 mm
Amount of strain at point B =
｛ 22/10 ｝ x 500
µ
ε )
=1100
µ
ε )
Where the measurement is based on the quarter-bridge configuration with a gauge factor of 2.00.
ＣＡＬ値
a
Ａ
B
b
波形測定
Waveform
Measurement
b (Amplitude at point B)
a (Amplitude of calibration value)