Precautions To Observe When Performing Measurement; Noise Countermeasures - GRAPHTEC MT100 Quick Start Manual

6. Precautions to Observe When Performing Measurement

Please be sure to read the following carefully in order to prevent electric shocks or shorts.
DANGER
• Do not apply voltage of AC30Vrms or 60VDC or above between the analog input section and main unit
(GND terminal), or between each analog input channel.
• Do not apply radio-frequency signals with high voltage (50KHz or above).
Input Circuit Diagram for Analog Input (Voltage, Thermocouples)
CAUTION
Capacitors have been incorporated into the input circuit to increase the noise elimination capability.
After voltage measurement, when the inputs have been disconnected, there will still be some electric
charge remaining. Before starting another measurement operation, short-circuit the + and - terminals to
enable self-discharge.
The MT100 has a scan system.
While in the status (open) in which signals are not input to the input terminal, measured results may be
influenced by signals from other channels.
In such a case, turn OFF the input setting or short circuit +/-.
If signals are input correctly, measured results are not influenced by other channels.

7. Noise Countermeasures

If the measurement values of the MT100 vary due to external noise, the following countermeasure is recommended.
(The effect varies depending on the noise type.)
Example 1: Connect the ground terminal of the MT100 to the ground (see the following figure).
Example 2: Connect the ground terminal of the MT100 and the ground terminal of a measurement
target (see the following figure).
Example 3: Set the filter to other setting than OFF in the AMP setup menu.
Example 4: Set a sampling interval at which the digital filter of the MT100 is effective (500ms or more).
To be connected to the chassis of the
measuring target (Functional grounding)
29
Channel Switching Relay
To be connected to the
power ground
(Protective grounding)