# Inductance of coile dup cbale on winch (twisted pair or just two strand)

1. ## Inductance of 100m of coiled up cable on winch (twisted pair or just two strand)

Hi,
The cable seen at 4:50 of this..

..is 100m long. Since it comprises "go" and "return", the inductance of the coiled up cable on the winch will be very low.
Do you know a formula to calculate this?
1...for twisted pair cable
2...for side-by-side cable

..or just a rough estimate of the coiled up cable inductance as shown here (100m).

I'd guess 200uH for the inductance...since mains cable (side-by-side) is approx 1uH per metre when un-coiled...so estimate 2uH per metre for coiled up.
I'd estimate 70uH if it was twisted pair.

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2. ## Re: Inductance of coile dup cbale on winch (twisted pair or just two strand)

Inductance of a balanced line depends on conductor geometry. Twist has no considerable effect, except for slightly increasing the effective length.

Conductive material in the vicinity (e.g. a cable shield or other wires) tends to reduce inductance. Mutual inductance in a coil can increase TP inductance, but due to arbitrary coupling factor sign, I would expect only a low average increase. Factor 2 sounds unrealistic.

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3. ## Re: Inductance of coile dup cbale on winch (twisted pair or just two strand)

agreed - twisted pair and side by side is essentially the same thing, for send & return coiling has no effect ...

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as to the drones - eventually the weight of the wire will be a severe limiting factor for height - and distance from spool ...

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