ECN Forum Forums General Topics of the Trade Non-US Electrical Systems & Trades Remote 11kV switching?

I came across this power pole on a tiny rural back lane some weeks ago, but didn't have my camera with me at the time.

I was out that way again yesterday so I took a slight detour to get some pics:



It's a standard 11kV distribution line, but it sure looked a little different which is what made me take a closer look.

On top of the cross-arm are fairly standard-looking air-break switches, with an operating rod and padlocked handle mounted near the bottom of the pole, such as might be found anywhere:



But what's that other equipment? A round unit with six HV terminals connected to each side of the lines:



To the right of that is a small transformer tapped across two phases and feeding down to a steel equipment cabinet near the bottom of the pole.

Just to the left of the pole and slightly above the barbed-wire you can see a small radio antenna.

Could this be a radio-controlled system to allow remote switching?

Paul,
You are quite right actually.
This sort of thing is used for Automatic Sectionalising of the HV lines during Faults, so that the whole peocedure can be done from the Control room.
And it saves us Faultsmen, rushing around opening and closing Air Break Switches, and allows us to do useful things like checking the Drop-out fuses along a given road.

A techno-buzzword for this arrangement is SCADA, “supervisory control and data acquisition.” The 6-bushing round can is typically a sectionalizing switch. Many out west are standalone, with local controls to “test” the line by a recloser, for often overhead-line faults are temporary; caused by lightening, tree or bird contact.

Earlier radio was single direction, in that the control room could transmit an open/close command with only indirect indication of switch operation—i.e., the neighborhood lights came on. More recent is fully duplex/bidirectional radio, so when a close command is sent, in a few seconds it sends back a confirmation from a mechanical auxiliary contact buried in the sectionalizer. If there is low-voltage AC closeby, {less than a few spans away} the switch auxiliary power is derived from that, but in more remote situations a local control-power transformer is installed.

It is expensive to install this type of switching, but if there is a history of temporary faults in an area, they are worth the money. Besides, having to get out in the middle of a windy night to manually operative a switch is not too “convenient.” Especially in bad weather, troublemen can be very opinionated about when and where the next one is needed.

Thanks guys. I figured that this had to be some kind of remote sectionalizing arrangement, but hadn't come across one before. Of course, in England we don't have places anything like as remote as out West, or even NZ, and everything tends to be on a much more compact scale.

This pole, however, is located in what could be termed a remote location by English standards: Two or three road miles out of town, down some of the narrowest and twistiest back lanes in the area.

The line going off to the right in the first photo feeds across an area known as High Hill. This being Norfolk and fairly flat on the whole, high is a relative term, but it is certainly higher and more open, exposed ground that much of the surrounding area, so maybe this line is more susceptible to damage in winter.

Couple that with the "remote" location and it makes sense.

P.S. For those with a UK road atlas, this is the area between Stalham and East Ruston, Norfolk.


[This message has been edited by pauluk (edited 06-19-2004).]

Well what d'ya know? I found another one!

After this set-up and the 3-wire 240/480 I've been looking a little more closely at overhead wiring to see if I've just been missing things that were right under my nose!

This remote switch is about 15 miles from home, but you can see the whole setup with equipment cabinet and antenna a little more clearly:

A couple of notes… The concept of automatic reclosing applies only to overhead distribution and transmission lines, with mostly short-lived faults from lightning and tree-branch exposure. Temporary faults are just about unheard of in underground systems, as is obviously the case for premises {inside} wiring.

Depending on age, sectionalizers may use mineral oil, sulfur hexafluoride gas or vacuum for insulation around the 11kV contacts.

The custom "squirrel fence" in the third pic looks handy.

Those little barbed wire fences are fairly common. Here's a transformer you've seen before which has them on the poles:

Hello

As this is my first post allow me to introduce myself. I am an electrical engineer working for the distribution company on the Isle of Man ( a small island in the Irish sea between the UK and Ireland ). I deal with all voltages from 230V to 90kV and work on maintenance and faults. I've been following the forum for a while now, and have found some useful information on it, and loads of very useful photographs!

Back to the images - on the island we use reclosers as shown in the photos together with smart links or sectionalisers. These can be programmed to drop out after a set number of trips in a certain timespan.

In most rural areas auto reclosers are fitted at the primary susbstations where the 11kV leaves the substation. They will also be fitted as bjarney says in areas which are prone to overhead line faults, together with the sectionalisers. This allows the fault to be cleared quickly, and means the power is restored to the majority of people before they can even start dialling the fault numbers.

We have numerous reclosers and sectionalisers on our system, even though the island is only 30 miles long by 15 wide. It keeps the CML down a treat and allows you to pinpoint the area of the fault much more easily by only getting calls from the vicinity of the fault.

Have a nice day

Ian

Hello Ian, and welcome to the forum.

Your description of your local network set me wondering whether the island has a higher than average incidence of thunderstorms and strong winds, given your location in the Irish Sea.

I remember several years ago seeing a whole page of storm instructions in the front pages of a Manx telephone directory, which seems to support that.

For those not too familiar with the British Isles, here's a map which shows the island's location: