What are the forces in play when a HVDC cable link interferes with a telecoms line within its route?
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Q: What are the forces in play when a HVDC cable link interferes with a telecoms line within its route?
Anon (UK)
A: The potential for interference between a DC link and telecommunication circuits depends on several factors:
DC converter harmonic generation, i.e. magnitude, frequency spectrum and degree of balance
Effectiveness of any dc side harmonic filtering deployed
Mutual electromagnetic coupling between the DC link and the telecommunications circuits, i.e. circuit proximity and length of exposure. Close proximity with long parallel exposure gives high coupling.
Type of communications circuit, i.e. audible frequency range telephone wire circuit
Harmonic cancellation, i.e. degree of harmonic balance on DC circuit (pole mode or ground mode), DC cable proximity (close laying versus spaced laying), use of twisted pair telephone circuits
Electromagnetic shielding of cable circuit or telephone circuit, i.e. use of conductor screen or metallic conduit.
The proper construction of the telephone circuit is very important for interference mitigation, e.g. use of twisted pairs and screening.