Just wan't to throw out a question,
Where you come from, how is three phase metered, in a Domestic or Light Commercial Installation, assuming that it is 3Phase+ Neutral.
Also, how would the Mains fuses be sized?.
As over here, the Rate at which a customer is charged, is based upon the maximum current draw of the fusing.
Your thoughts on this Topic, please-

With analogue meters up to 200A. Above that digital meters with automatic reporting. That way the PoCo can charge you per hour basis: useful when it's cold.

Many houses are heated electrically and the price of electricity is more than $.1 per kWh at the moment, ten times that of the price in summer. (In case of a rainy spring/summer they have to find something to do with the power, as they can't just open the hydropower dams. They were forced to in 2001, but the water took a few houses with it.)

There is talk of remote controlled meters, so that the PoCo can turn off non-critical load at peak load.

Fuses are matched to declared load. NIE (Northern Ireland Electricity) have a number of standard tarrifs. Usually TP&N loads up to 100a are direct via the meter. After this CTs are employed.
Fuses are usually BS1361 type 11B.
Of course there are many special arrangements that can be made for heating etc.

Excuse my ignorance, but what are CTs?

Current Transformers. Instead of directly reading the power flowing through the conductor, a CT senses the magnetic field induced around the conductor as current flows.

EDF in France has some really complex tariffs geared toward electric heating and encouraging users to economize during periods of high demand.

Their "Option Tempo" divides the year up into red, white, and blue days. I can't recall the exact numbers off hand, but they're limited to something like a maximum of 30 red days per year, and a greater quantity of white days. Red days are the most expensive, white moderately so, and blue the "standard" rate. Within each of those divisions there are then day and night rates, giving SIX distinct cost-per-unit rates.

Within the limits set out, EDF decides each evening whether the following day will be red, white, or blue, based upon the weather forecast from the meteorological office in Toulouse. Consumers can have installed a signal box which displays the appropriate indication for the following day so that they know how much they will be paying.

Paul,
That EDF system sounds, pretty good, it lets you know how much you are going to be charged, per kWh, and wether or not you should turn off your Non-essential loads, during the Red and White Periods.
Over here it is one big mess, people changing Power companies, to get the best deal, none of them staying long enough to enjoy any Good Customer bonuses.
I blame the last Government on this, they wanted cheap prices for Domestic places,
It has been like a game of Bullrush, but the Domestic people have all lost out, in favour of the Commercial and Industrial users.
It is based on kWh usage/year over here.
This is not good.

The situation is getting complex in the U.K. too. The deregulation of recent years means that you can buy your electicity from a variety of companies. I might be in East Anglia (East of England), but if I wanted I could contract with Scottish Power for my energy. Similarly, if I were to move p to far north of Scotland I could still keep paying TXU Energi (which took over Eastern Electricity a while ago) for my electricity.

It's all become quite bizarre; after all, the stuff still comes along the same cables as before.

Scott35,
Is there any chance of getting a diagram with respect to the use of Current and Potential Transformers (CT's and PT's),
with regard to metering.
I can scan a couple of diagrams that I have,
for use in Technical Reference Area.

[This message has been edited by Trumpy (edited 02-07-2003).]

ahh in usa for three phase meter we have dricet reading meters up to 200 amps BUT we also have " bolt on " meter it go up high as 600 (old versions are 400a) and new one are electronic meter and they are very accture reading no matter what leg or volts or wye or delta it dont affect it at all. my shop have big bolt on 400 a 480 wye service with electronc meter for higher currents class we use the ct ( it start at 200 a then go up what ever they use in the system i see it with ct with BIG 3.000 amps service and we have multi rate for big commercal user but for small commercall useer it have flat fee per KWH cost

merci marc

I was looking at overhead residential distribution cabling here in Ireland today a was just wondering exactly what's used. (Modern stuff would all be underground)

the poles carry 5 wires along the lowest one looks physically different cable from the other 4. Each house taps into one of the phases only and it seems to vary house to house to spread the load. Local shops etc seem to take connections from all 5 cables! for 3phase.

What's the 5th wire? system provided earth/ground?

The area's wiring would prob. date from the 40's / 50s some of it perhaps a lot older although im sure it's been upgraded over the years.

djk,
It wouldn't be some kind of a Pilot wire for a load control system, would it?.
Failing that, are you sure that it is not a wire for the streetlights control, as these are normally run off a different circuit from the distribution lines, this circuit is normally centrally-controlled, from a Daylight(photocell) switch.
Hope this helps.

Perhaps it is/was for controlling street lighting as it looks like a thinner cable

A fifth wire to operate contactors for street lights used to be quite common in some British towns and villages. I still sometimes see old poles where the control wire has been removed but the brackets that used to hold the insulators for the fifth wire are still there.

djk/Paul,
Pilot wires were used over here for years, in some places, they are still used.
I remember when I first started out as a Trainee Liney, you had to "Identify all conductors", in some places there were Pilots
for Hot Water, Street-lights, Load dumping relays, and a spare wire that was taken back to the control centre, all on the same pole as the normal 3p+N.
Pilots, killed a friend of mine, that I done my time with, there are 400V between all of them, they are never on the same Phase.

Trumpy,


Just found this post today!

Ya, send them on over (scan and E-mail), and I'll see they get placed in the reference section.

I have some EE manual schematics for KWH meters, plus KVAR meters.
When time allows I'll draw up a few.

Scott35 S.E.T.

Most of the controls for this sort of thing are done by sending short HF signals down the lines these days.

For years it was common practice for the "Economy 7" domestic night rate to be governed by a timeclock installed alongside each meter. The "Radio Teleswitch" is now common. No clocks to adjust, and the PoCo can adjust the times from a central control point if they need to.

Yeah Paul,
A lot our traditional Ripple supply signals,
are now sent by UHF and are injected at various points around our local Grid system,
saves having Pilot systems.
Another development over here, is the use of UHF (Almost like Packet Radio), to energise and de-energise certain parts of the HV and EHV systems, around here.
But good old Radio Telephones are still used to make sure that the Disconnection has actually happened, this will never be made obselete.
Don't trust this packet stuff, for this type of work though, what about Interference, but I am sure that they have got this figured into the equation.
Here's hoping!.