Inductive coupling: Difference between revisions
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== Definition == | |||
The disturber and the victim are coupled by a magnetic field. The level of disturbance depends on the current variations (di/dt) and the mutual coupling inductance.<br>Inductive coupling increases with: | The disturber and the victim are coupled by a magnetic field. The level of disturbance depends on the current variations (di/dt) and the mutual coupling inductance.<br>Inductive coupling increases with: | ||
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*The load impedance of the disturbing circuit. | *The load impedance of the disturbing circuit. | ||
== Examples == | |||
(see '''Fig. R28''') | (see '''Fig. R28''') | ||
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== Counter-measures == | |||
*Limit the length of parallel runs of disturbers and victims to the strict minimum | *Limit the length of parallel runs of disturbers and victims to the strict minimum | ||
Revision as of 08:48, 17 June 2011
Definition
The disturber and the victim are coupled by a magnetic field. The level of disturbance depends on the current variations (di/dt) and the mutual coupling inductance.
Inductive coupling increases with:
- The frequency
- The proximity of the disturber to the victim and the length of the parallel cables,
- The height of the cables with respect to a ground referencing plane,
- The load impedance of the disturbing circuit.
Examples
(see Fig. R28)
- Nearby cables subjected to rapid current variations (di/dt)
- Short-circuits
- Fault currents
- Lightning strikes
- Stator control systems
- Welding machines
- Inductors
Fig. R28: Example of inductive coupling
Counter-measures
- Limit the length of parallel runs of disturbers and victims to the strict minimum
- Increase the distance between the disturber and the victim
- For two-wire connections, run the two wires as close together as possible
- Use multi-core or touching single-core cables, preferably in a triangular layout
- Position a PEC bonded at both ends and between the disturber and the victim
- Use symmetrical transmission systems on correctly implemented, symmetrical wiring systems
- Shield the disturbing cables, the victim cables or both (the shielding must be bonded)
- Reduce the dv/dt of the disturber by increasing the signal rise time where possible (series-connected resistors or PTC resistors on the disturbing cable, ferrite rings on the disturbing and/or victim cable)
