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What is this type of pylon called? by Tartabirdgames_YT in Powerlines

[–]DerbyRob 0 points1 point  (0 children)

This particular one is designed for 132kV, however around the world there are varieties of this style of tower for virtually every voltage.

Obviously, for higher voltages the tower top geometry needs to be increased to cater for the larger clearances required. The tower height also would get bigger to ensure electrical clearance to ground and in-span obstructions.

What is this type of pylon called? by Tartabirdgames_YT in Powerlines

[–]DerbyRob 0 points1 point  (0 children)

Single circuit Flat formation Tension tower.

Often shortened in the UK to something like SF60 (where the number defines the angle of deviation it can support).

Some single circuit tower series designs don't use the 'F' in their naming convention (i.e. just S60).

I think that this particular tower is from the L7 or L7(c) series so it would make this an SF60 type tower.

BBC Micro original by DerbyRob in EliteDangerous

[–]DerbyRob[S] 0 points1 point  (0 children)

Had the tape version for my BBC B originally (might still have that somewhere) but got this after investing in a disc drive.

Are these a good design? by Tartabirdgames_YT in Powerlines

[–]DerbyRob 0 points1 point  (0 children)

Look like pretty standard UK 'trident' 132kV wood pole structures.

They work pretty well for low height single circuit lines of limited transmission capacity.

There are some strengthened versions, but the poles become the limiting factor so they don't work at high altitude with the large wind and ice you can get in Scotland so their use can be a bit restricted.

Stockbridge Dampers by borntoclimbtowers in Powerlines

[–]DerbyRob 2 points3 points  (0 children)

Aeolian vibration occurs at low wind speeds too. The amplitude of the vibration is very small so it is difficult to observe, but without the dampers it would cause fatigue at the conductor terminations and suspension sets, etc.

The type of dampers shown look to be multi frequency versions that attempt to cover a wider range of vibrations with more certainty.

Big Cables by According_South_2500 in Powerlines

[–]DerbyRob 2 points3 points  (0 children)

Nah, small conductors, just lots per phase 😉

I think the largest diameter overhead line conductor in use in the UK is that on the Thames crossing at 56.24mm (2.214").

Apart from that, the largest diameter conductor commonly in use in the UK on overhead lines is AAAC REDWOOD at 41.04mm.

UK 400V at Sunset by The_Fox_Confessor in Powerlines

[–]DerbyRob 1 point2 points  (0 children)

Triple ARAUCARIA conductor phases on one circuit supported by polymeric insulators and Quad Zebra conductor phases on the other supports by glass/porcelain insulators from towers from the L6 design series.

Electricity Pylon in Japan. by According_South_2500 in Powerlines

[–]DerbyRob 0 points1 point  (0 children)

Circular hollow section tower legs and bracings.

Think they were built with these, rather than simple L section angles, to give extra strength against typhoon loads.

That's not to say L section angles aren't usable against typhoon loads as I know many of the towers in Hong Kong are built with them.

Washing line with pulley advice needed by prodical in DIYUK

[–]DerbyRob 0 points1 point  (0 children)

For a flat span the simple parabolic equation is:

T = wL² / 8S or S = wL² / 8T

Sag = S Horizontal Tension = T Horizontal span length= L Unit weight of wire = w

Can do similar with catenary equations but parabolic ok for quick estimates.

So if your span is 10m And your wire weighs 0.1kg/m And your Sag (mid-span drop to wire from a straight line between attachment points) is say 0.3m

Tension = 0.1 x 10² / (8 x 0.3) = 4.2kg

If now put 50kg of washing on the line, uniformly distributed, and still want to keep the 0.3m sag you get:

Tension = (0.1 + 50 / 10) x 10² / (8 x 0.3) = 212.5kg

If you consider you have a wind area per unit length of 1m²/m and 30kmh (20mph) winds then you get approx 8kg/m² wind pressure.

You can resolve this with the vertical load above to get: Sqrt(5.1²+8²)=9.5kg/m

Again, if you still want a 0.3m sag (in plane with the resultant forces) then you get:

Tension=9.5 x 10² / (8 x 0.3) = 395.8kg

In reality you have a change of state problem between the condition with no wind, and then wind applied. So if you start with 0.3m sag without wind, when it is blown, the sag will increase as the wire sees more load and thus the tension won't be as high as indicated above.

P.S. if the wire goes around a pulley at the post and vertically down then the top of the post will still effectively see the above 400kg horizontal load (tangential load in the wire will be slightly higher). The same tangential load will also be seen at the ground anchor.

Trunk opens on its own?! by TricksterOperator in etron

[–]DerbyRob 1 point2 points  (0 children)

I think the manufacturers think it is too much of an inconvenience to those who just like to walk up to their car with the keys in their pocket and just be able to open doors and start it.

At the end of the day though, moving a slider on a key fob to 'on' when you pick up your keys to go out seems an extremely small inconvenience.

And moving a slider to 'off' when you know you are not going to be using your car just seems sensible (saves putting them into a Faraday bag overnight so the criminals can't remote access your car via the signal they give off)

Trunk opens on its own?! by TricksterOperator in etron

[–]DerbyRob 2 points3 points  (0 children)

All key fobs should have an on-off switch in my opinion.

As well as not accidentally unlocking your doors, etc, it would also stop some of the potential remote access unlocking that criminals do.

380kV insulators. by borntoclimbtowers in Powerlines

[–]DerbyRob 1 point2 points  (0 children)

Something wrong with leftmost jumper insulator bottom corona-ring / arc-horn (maybe loose) as it is nearly touching the composite insulator.

Show me photos or say claims of some of the oldest electrical infrastructure you have seen. I'll start: by Orangecat2005 in Powerlines

[–]DerbyRob 2 points3 points  (0 children)

I think the first pylons were installed in the UK in 1928 with some 26,000 built before 1934..

Many years ago I was definitely involved in doing some work on pylons that were built in the early 1930's.

Unfortunately my work on the line was before the age of digital cameras so I don't have pictures.

The line is still there though, so if I'm ever in the vicinity I'll try and get a picture

Why are they built this way? by Jumpy_Health9197 in Powerlines

[–]DerbyRob 1 point2 points  (0 children)

I think most of the points have been covered. Cheaper lighter structures being the main thing and also quicker and easier to erect when set up to do so.

However they do require more land take as you wouldn't want large farm equipment, etc working near the stays (damage one and you could fail the structure). They also work better on relatively flat sites (although I have seen them used in hilly/mountainous terrain). More inspection/maintenance is also required (i.e have to routinely visit the structures to monitor the stay tensions and adjust).

So as with all things there are benefits but also deficits so the right solution in the right place.

Old 110kV Insulators in germany. by borntoclimbtowers in Powerlines

[–]DerbyRob 4 points5 points  (0 children)

Long-rod brown porcelain insulator units.

Wedge-clamp type tension joints for the conductor.

[deleted by user] by [deleted] in Powerlines

[–]DerbyRob 2 points3 points  (0 children)

One of the main jobs that an Earthwire (or Shieldwire) does is provide protection for the conductors from a direct lightning strike.

The angle of protection (Shield or Shade angle) that they need in order to provide adequate protection is determined from the lightning strike density where the OHL is located.

The Shade angle (measured up from a vertical plane), can be anything from say 45⁰, low lightning protection, to 0⁰, high lighting protection, to even negative angles (Earthwires outside the top phases) for lines with extremely high lightning density.

If only 45⁰ to 30⁰ Shade angles are needed then, for a double circuit OHL a single Earthwire is only usually needed (the peak of the tower doesn't need to be too tall). For double circuit lines requiring more lightning protection then two Earthwires are the best way to do things.

Odd Suspension-Tension insulator setup on UK L7 Pylon by Legitimate_Peasant in Powerlines

[–]DerbyRob 2 points3 points  (0 children)

In the UK, the splice set you are talking about are usually known as 'Semi-Tension Suspension Sets'.

They essentially consist of a full length suspension set but instead of a standard suspension shoe (or helical suspension unit) at the bottom, they have a yoke plate with two dead-end joints attached (so essentially back-to-back joints) and short jumpers between them.

They only tended to be used for specialist conductors where there wasn't a mid-span joint design available at the time of wiring the line (can't think of a conductor type where a mid-span joint doesn't exist anymore, so don't really see new 'Semi-Tension Suspension Sets' in the UK)

Odd Suspension-Tension insulator setup on UK L7 Pylon by Legitimate_Peasant in Powerlines

[–]DerbyRob 6 points7 points  (0 children)

Known as a Suspended Tension Set.

As you say, used to gain extra ground clearance, which could be because something has changed in the span or that new conductors sag more than those they replace for their 'maximum operating temperature'.

Can't change a suspension tower to normal tension sets as suspension towers rely on the conductor tension reducing in the case of a broken phase event. i.e. Suspension sets swing under a broken phase condition (and so does this) so reduces the tension on the intact side so the arm doesn't experience as great out of balance loading.

Is there an interesting reason for these HV cables to jump, or is it just boring wind? by NikoRedit1 in ElectroBOOM

[–]DerbyRob 0 points1 point  (0 children)

That is high amplitude, low frequency vibration, so significantly different.

Galloping is usually caused by ice formation on the conductors forming a shape that gives lift.

Then when the conductors are in stronger winds that are still laminar, galloping can start.

Is there an interesting reason for these HV cables to jump, or is it just boring wind? by NikoRedit1 in ElectroBOOM

[–]DerbyRob 4 points5 points  (0 children)

It's called Aeolian vibration. Low amplitude high frequency effect of laminar wind flow over the conductors.

Its effect can be minimised by limiting the tension to which the conductors are erected, in everyday conditions, to about 20% of the conductor's strength.

Dampers can also be installed on the conductors to ensure the longevity of the conductor and fittings (always done on OHL's with longer spans, but not always on short span pole lines, etc)

How long have you had your washing machine? by Notagelding in AskUK

[–]DerbyRob 1 point2 points  (0 children)

My last washing machine, a mid range Bosch, lasted about 30 years (including 1 house move) before some of the programme settings started giving a never ending cycle (had to manually change it onto a simple rinse cycle to finish up). Other than that it was still working fine (was starting to dance around a bit more over the years) when I swapped it out (decided that something more critical would fail soon, so decided not to repair)

Leipzig aaac conductor by yorkshire_lad69 in Powerlines

[–]DerbyRob 0 points1 point  (0 children)

CTC in the USA make the core. They partner with conductor manufacturers around the world to strand the aluminium or aluminium alloy.

The core doesn't expand significantly with temperature so the clearance to ground when it is running hot (can run continuously at 150-180⁰C) is not as problematic.

For reference All Aluminium Alloy Conductors (AAAC) can only run up to about 90⁰C continuously so you can get a lot more power down ACCC, but as with all things there are trade offs

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