GRAPHTEC GL820 - Precautions to Observe When Performing Measurement

2−21
CHAPTER 2 Checks and Preparation
2.14 Precautions to Observe When Performing Measurement
Please be sure to read the following carefully in order to prevent electric shocks or shorts.
 • Donotapplyvoltageof60Vp-porabovebetweentheanaloginputsectionandmainunit(GND
terminal), or between analog input channels.
 • Donotapplyradio-frequencysignalswithhighvoltage(50KHzorabove).
 • BesuretouseonlytheACadapterprovidedasastandardaccessory.Theratedpowersupplyrangefor
the adapter is 100 to 240 VAC, and the rated frequency is 50/60 Hz. Do not use any other voltages.
● Maximum input voltage
If a voltage exceeding the specified value is input, the semiconductor relay in the input section will be
damaged. Never input a voltage exceeding the specified 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
<Between input terminal/input terminal (B) >
•Maximuminputvoltage :60Vp-p
•Withstandvoltage :350Vp-pat1minute
<Between input terminal/GND (C) >
•Maximuminputvoltage :60Vp-p
•Withstandvoltage :350Vp-pat1minute
GND
● 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 GL820 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.