Ground loops

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Underlying technologySignal transmissionGround-related signalsGround loops


A ground loop can be the result of two devices being connected that are both to be at the same potential, often ground. These usually become noticeable in the form of more or less strong low-frequency interference of the actual signal.



The reason for this is that a closed loop (ground loop) is created where a current IMis induced by alternating magnetic fields (transformer principle). This in turn causes a voltage in the total resistance R of the ground conductor that interferes with the actual Us signal.

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The following measures can be taken to minimise or eliminate these interferences:

A.Minimise all resistances (such as plugs, conductors) in the ground conductor of the signal.

B.Magnetic shielding of the sources of the impacting alternating magnetic fields.

C.Measures combining A and B

D.Separating the ground loop with the aid of (explosion-protected) isolating repeaters.



Separating earth or equipotential bonding is not permitted.


They fulfil important, essential protective and interference-suppressing functions.



Click to expand or collaps object.        Figure, loop separation by isolating transformer:



The isolating repeaters are symbolically represented by the transformer symbol. These could also be electronic systems with an electrical or optical transmission path.



If isolating repeaters are used inside a hazardous area they must meet the requirements of the area's protection class.


See also:

Kapitelseite Differential signal transmission



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