Appendixd - Ground Loop Phenomenon; What Is Ground Loop; Cabling Recommendations - SeaLevel ULTRA COMM+I.LPCI User Manual

What is Ground Loop?

Ground loop Phenomenon occurs when two (or more) pieces of equipment are connected together with a common
ground and a different ground potential exists at each location. This current can cause the connected equipment to
experience noise that in turn causes data transmission errors. In the extreme this ground current can cause equipment
malfunction or even destruction.

Cabling Recommendations

When connecting the ULTRA COMM+I.LPCI in a RS-485 network, care should be taken that both ends of the
network are not isolated from ground (see Figure 8). This "floating" ground condition could cause the capacitive or
inductive coupling of voltages that will cause a break down in the DC to DC converter circuit or in the opto-isolator
circuit. This condition will cause data errors and possibly destruction of the receiver circuit.
Isolation
Sealevel Systems ULTRA COMM+I.LPCI
Appendix D - Ground Loop Phenomenon
A
Isolated
Adapter
Barrier
Figure 8 – ULTRA COMM+I.LPCI cabling example
Appendix D - Ground Loop Phenomenon
B
DATA+
Non
DATA-
Isolated
Ground
Adapter
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