MR8740、MR8741_user_manual_eng_20191016H.pdf - 第186页

7.9 Setting Details of Modules 174 This setting allows you to choose between voltage me asurement and accelera- tion measurement (ch argeoutput or built-in pre-a mplifier) for a channel. A channel can m easure either on …

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7.9 Setting Details of Modules
173
6
Chapter 7 Utility Functions
7
See: "Opening the [Each Ch] sheet, Making a Channel Selection" (p.161)
Mode Switches between voltage measurement and RMS measurement.
Select
Response The response time for RMS measurement can be set to three speeds: Fast, Nor-
mal and Slow.
The response time can be set to [Slow] to stabilize the measured value when
the frequency is low or when severe fluctuations are present.
Select
7.9.9 Setting Model Model U8974 High Voltage Unit
Selections Description
DC
Voltage measurement (Default setting)
RMS
RMS measurement
Selections Description
Fast
Response time is set to 150 ms.
Normal
Response time is set to 500 ms. (Default setting)
Slow
Response time is set to 2.5 s.
7.9 Setting Details of Modules
174
This setting allows you to choose between voltage measurement and accelera-
tion measurement (chargeoutput or built-in pre-amplifier) for a channel.
A channel can measure either one of them.
[Voltage] mode and [PreAmp] mode use BNC connectors, whereas [Charge]
mode uses miniature connectors.
Model U8979 can automatically recognize TEDS-compliant
*
sensors.
*: Transducer electronic data sheet
See: "Opening the [Each Ch] sheet, Making a Channel Selection" (p.161)
Mode Switches the measurement mode.
Select
(When setting mode to [PreAmp])
Move the cursor to the [Sens.] box and execute [TEDS Load].
Acquires sensitivity of a connected sensor. However, the instrument can acquire
sensitivity of TEDS-compliant acceleration sensors with a built-in pre-amplifier
only.
When sensor sensitivity has been acquired, it is automatically set.
A.A.F The anti-aliasing filter can prevent aliasing distortion that may be produced dur-
ing FFT calculation. The cutoff frequency automatically changes according to the
sampling rates or frequency range (for the FFT function) settings.
Select
7.9.10 Setting Model U8979 Charge Unit
Setting the measurement mode to [PreAmp] allows Model U8979 Charge Unit
to constantly provide power (3.5 mA, 22 V) to sensors. Set any measurement
mode other than [PreAmp] or tum off the instrument before connecting a sensor
or probe with a BNC terminal to avoid an electric shock or damage to the mea-
surement target.
Mode Measurement target Measurement sensitivity
Voltage
Voltage —
Charge
(Default setting)
Charge-output acceleration
sensor
0.1 pC/(m/s
2
) to 10 pC/(m/s
2
)
PreAmp
Acceleration sensor with a
built-in preamplifier
0.1 mV/(m/s
2
) to 10 mV/(m/s
2
)
Selections Description
OFF Disables the anti-aliasing filter. (Default setting)
ON Enables the anti-aliasing filter.
(Disabled when the external sampling is used, or the sampling rate
is set at 100 kS/s or faster)
7.9 Setting Details of Modules
175
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Chapter 7 Utility Functions
7
Sensitivity You can enter sensor sensitivity to two decimal places. For a charge-output
acceleration sensor or non-TEDS-compliant sensor, enter its sensitivity marked
on the sensor, which represents sensitivity per meter per second squared.
Setting example for sensor sensitivity
Example 1 For a sensor with its sensor sensitivity per meter per second
squared marked
Example 2 For a sensor with its sensor sensitivity per gee (G) marked.
For a sensor with its sensitivity marked, enter a quotient of the marked sensitivity
divided by 9.8 m/s
2
.
To convert a unit from meter per second squared into gee (G)
The instrument measure charge quantities per meter per second squared. You
can convert such charge quantities into those per gee (G) using the scaling func-
tion.
See: "7.4 Converting Input Values (Scaling Function)" (p.148)
Configure the scaling setting as follows;
Example 1 Specifying a conversion ratio
Example 2 Specifying two points
Sensor sensitivity (setting value)
1.08 pC/(m/s
2
)1.08
Sensor sensitivity (setting value)
For sensor sensitivity of 64 pC/G
64.0 / 9.8 = 6.53061... pC/(m/s
2
)
6.531 (to two decimal places)
Ratio 0.1020E+00 (= 1/9.8)
Offset 0.0000E+00
Units G
Input1 9.8000E+00 Scale1 1.0000E+00
Input2 0.0000E+00 Scale2 0.0000E+00
Units G