Hioki LR8400-20, Инструкция по эксплуатации

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Appendix 8 Concerning Noise Countermeasures
A
18
Insulation from noise sources (temperature measurement by thermo-
couple)
The analog input channels are insulated from the chassis and each other. Therefore, the
HiLogger allows you to attach the thermocouple directly to a conductor with a potential to
measure it, provided that the voltage to ground does not exceed the maximum rating. If
noise is likely affect measurement, wrap heat-resistant tape around the thermocouple for
insulation, or use an ungrounded thermocouple and electrically insulate the input line.
Setting the Digital Filter
To remove noise from input signals, the digital filter can be set for the analog channels.
Select 50 or 60 Hz to match the local line frequency.
When 50 or 60 Hz is selected, longer recording intervals produce lower cut-off frequen-
cies and better noise suppression.
A larger number of channels (input units) raises the cut-off frequency for a specific
recording interval, and weakens noise suppression.
See: "Chapter 11 Specifications": "Cut-off frequency" (p .239)
Inserting a Capacitor in the Signal Line
When noise affects the signal source directly or when measuring high-frequency pulses,
it is effective to insert a capacitor between the "+" and "-" input terminals so that the noise
does not enter the 8430-20. When inserting a capacitor, use one with a rated voltage that
is equal to or exceeds the input voltage.
When a capacitor is inserted between the "+" and "-" input terminals, there are no restric-
tions on the recording interval because the filter is applied before the channel scan oper-
ation.
The capacitance of the capacitor should range from several
μ
F to
several thousand
μ
F. Insert the capacitor between the "+" and "-" in-
put terminals.
Thermocouple
Device being
Tested HiLogger