Power supply ground loops
USER MANUAL
4.2. Error case with broken GND cable
You can imagine what will happen when the “high-current path” is open. The current will flow a
different way. Now the return supply path of the sensor is routed through the GND of the sensor input
from the DAQ device.
Image 2: Error case with broken GND cable
Important
Usually the internal circuitry is not capable of driving this high current. So the DAQ device may
be damaged.
4.3. Error case with not symmetric supply line resistor
In practice the supply wiring is more complicated like shown in this basic diagram. A cable brake on the
supply line is for sure the worst case. But also line resistances in the supply lines combined with different
supply current levels will cause unintentional current flow through the DAQ-system like shown below.
Image 3: Asymmetric supply line
V20-1 5/12
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