The input channels of the GN816 and GN816 are isolated. This means that the
input channel and amplifier are fully isolated from (earth) ground. In this context,
fully isolated means a very high resistance and a very small capacitive coupling
to ground. This is for safety and to avoid ground loops.
Characteristics per channel:
l
The input BNC connector is isolated from the system ground.
l
The isolated ground is externally accessible, as shown in Figure 12.27.
+
-
900 kΩ
100 kΩ
U
iso
U
diff
.
IN(+)
IN(-)
Isolated
channel
Non-isolated
system
Single-ended, isolated
ADC
Figure 12.27:
Single
-
ended isolated input channel
Using probes:
It is possible to use passive voltage probes with single
-
ended isolated inputs.
Using a standard passive 10:1 probe in combination with the GN815 and
GN816 results in the situation shown in Figure 12.28.
+
-
900 kΩ
100 kΩ
U
iso
U
diff
.
IN(+)
IN(-)
Isolated
channel
Non-isolated
system
Single-ended, isolated
ADC
9 MΩ
10 * U
diff
.
Passive probe
Figure 12.28:
Input channel with a standard 10:1 passive probe
Using a high voltage passive 10:1 probe in combination with the GN815 and
GN816 results in the situation shown in Figure 12.29. The voltage division is
done externally in the probe to maintain accuracy.
GEN3i
I3763-3.1 en HBM: public
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