GRAPHTEC GL840 - Page 57

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CHAPTER 2 Checks and Preparation
When using the Standard terminal (GL840-M/B-564) or the Screwless terminal
Please be sure to read the following carefully in order to prevent electric shocks or shorts.
•
Maximum input voltage
If a voltage exceeding the specied value is input, the semiconductor relay in the input section will be
damaged. Never input a voltage exceeding the specied value even for a moment.
* This applies to all the channels even if channel extension is used.
< Between +/– terminals (A) >
• Maximum input voltage : 60Vp-p (Range of 20mV to 2V)
110Vp-p (Range of 5V to 100V)
<Between input terminal/input terminal (B) >
Maximum input voltage : 60Vp-p
Withstand voltage : 350Vp-p/1 minute
<Between input terminal/GND (C) >
Maximum input voltage : 60Vp-p
Withstand voltage : 350Vp-p/1 minute
GND
+
-
+
-
+
-
B
B
C
C
A
GND
+
-
+
-
+
-
C
B
[ Temperature measuring ]
Thermocouple
Thermocouple
Thermocouple
[ Voltage measuring ]
•
Input Circuit Diagram for Analog Input (Voltage, Thermocouples)
50Ω
50Ω
500kΩ
500kΩ
0.05μF
0.05μF
+
-
Channel Switching Relay
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 GL840 has a scan system.
While in the status (open) in which signals are not input to the input terminal, measured results may be
inuenced 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 inuenced by other channels.