Limiting current on a sub main

[PBC_1966]

As I wrote recently, it now seems to be that either 'duff equipment' was plugged in or else there were appreciable loads in addition to what you've been told about.

The latter seems quite likely.

 

[JohnW2]

As I wrote recently, it now seems to be that either 'duff equipment' was plugged in or else there were appreciable loads in addition to what you've been told about.

The latter seems quite likely.

Possibly - although if the tripping happened fairly 'quickly' it would have had to have been a load appreciably in excess of 50A to trip a B32.

Kind Regards, John

 

[PBC_1966]

PG&E is private, but quite heavily regulated by the California Public Utilities Commission with regard to rates. And there's the whole California energy crisis business in recent years.

Interesting. How keen are people (and, more to the point, institutions) to be become shareholders in a company which is deliberately restricting/discouraging growth and profitability (even if that is forced upon them by regulation)??

I'm not sure of the precise details, but I believe the State of California/CPUC also have arrangements in place with regard to benefits and profits which actually make it quite beneficial to shareholders even though the rates are heavily regulated.

 

[PBC_1966]

It occurs to me that you and I have seemingly both previously agreed that OPDs should not be used to 'limit the load' - but that appears to be what the French are doing.

Certainly that's what EDF does to limit demand to whatever power level has been subscribed to. Within the installation, the délesteur is the device they use to shed non-priority loads to meet instantaneous demand for other loads. Some délesteurs have multiple outputs and can be set to various operating modes, such as always shedding loads in sequence successively as demand on the uncontrolled output increases (i.e. each output has a fixed priority level so it will always be output 1 disconnected first, then output 2 as load increases etc.), or shedding loads in turn each time demand increases (i.e. disconnect output 1 this time, then disconnect output 2 next time etc.).

http://www.hager.fr/professionnels/...-du-chauffage-electrique/delesteurs/18565.htm

Using one in the situation desribed might be awkward if people are just plugging portable heaters into general-purpose sockets all over the place though. I suppose with some careful planning of which sockets are on which output it might work, but it would be far from ideal and quite probably just lead to extension leads being used to run from uncontrolled sockets. The cost of the unit plus rewiring would probably be better invested in increasing the capacity of the sub-feeder; or if the problem is just excessive usage when electricity is included in the rent, it would probably be better to upgrade the feeder, if necessary, install a landlord's meter, and just bill per actual usage.

 

[ban-all-sheds]

From the consumer's point of view, that's little more than a 'paper exercise'.

I suggest you do a few more of those, comparing UK bills with French ones, for given consumptions and standing charges.

What matters to them is the overall effective cost per kWh (taking standing charge into account). For a French consumer using 6,400 kWh per year (allegedly the average French domestic consumption - see here ) that effective cost per kWh (for all their electricity) would rise from 0.1552 euros if they only wanted a peak supply of 3kW/15A to 0.1838 euros if they wanted a peak supply of 18kW/90A (comparable with the 'usual' UK domestic supply).

The higher of those two prices is competitive within the range you'd pay in this country for 6.4MWh. (But ironically more than EDF would charge you here )

This price structure is arguably particularly unfortunate ('unfair'?) for a consumer with very modest total electricity requirements, but occasional short-term high loads (e.g. a shower?).

Our price structure is unfair for a consumer with very modest total electricity requirements and no shower.

Our vehicle taxes are unfair for someone who wants a big car but doesn't do many miles.

Our property taxes are unfair for single people or couples who want to live in a large house.

LABTYD.

Even with a shower I'd be happy if I could reduce my bill by agreeing to limit my instantaneous demand, but I'm not given that option.

I dare say there are probably provisions for preventing this being exploited, but the EDF figures posted suggest that it would actually be cheaper in France to have multiple "3kW" supplies than to have one 9, 12 or 15 kW supply!

Look at the rate per kW of [the standing] charge.

I was commenting on the 'business model', which is pretty unique.

We cannot allow unfettered business models for energy supply and consumption.

If promotion ('encouragement of more use'), or even sale, of everything which had a negative effect on the environment or on public/individual health was 'outlawed', we would be living in a very different world!

I think you'll find there's a bit of a difference between outlawing something and discouraging excessive consumption via a pricing structure.

It's also interesting that, if the figures in the above link are to be believed, the average domestic electricity consumption in France (6,400 kWh/year) is about 39% higher than the figure given for the UK (4,600 kWh/year), despite the French price structure.

And despite the rarity (AIUI) of electric showers.

 

[ban-all-sheds]

It occurs to me that you and I have seemingly both previously agreed that OPDs should not be used to 'limit the load' - but that appears to be what the French are doing.

No - it is not an OPD.

 

[JohnW2]

It occurs to me that you and I have seemingly both previously agreed that OPDs should not be used to 'limit the load' - but that appears to be what the French are doing.

No - it is not an OPD.

Oh. What is your understanding of the nature of a "Réglage disjoncteur", then?

Kind Regards, John

 

[ban-all-sheds]

A load limiting (or if sophisticated, shedding) device. Clearly the cables to/from it would have to be appropriate for the load, but its function is not to provide overcurrent protection.

 

[JohnW2]

... but its function is not to provide overcurrent protection.

Quite so - and my suspicion is that, in the less-sophisticated cases, it's just an MCB. If that's the case, maybe I misunderstood what I thought we had agreed upon - because what I meant (and thought be had agreed about) was that I did not think it was correct/appropriate to use a device intended/designed to provide protection against overcurrent as a means of 'current/load limitation'. Did you mean something different from that?

Kind Regards, John

 

[stillp]

I realise that their are resource and infrastructure issues, with a lost of capital cost implications, but that nevertheless be a pretty unique business model. I think one would have to look very hard to find other large businesses that produced major disincentives to buy more of their product - it's a bit like "buy one, get a second for twice the price"!

Kind Regards, John

The water suppliers? The NHS?

 

[ban-all-sheds]

Quite so - and my suspicion is that, in the less-sophisticated cases, it's just an MCB. If that's the case, maybe I misunderstood what I thought we had agreed upon - because what I meant (and thought be had agreed about) was that I did not think it was correct/appropriate to use a device intended/designed to provide protection against overcurrent as a means of 'current/load limitation'.

No - I mean the same.

It's not intended to protect the cables from overcurrent, any more than it would be if someone in this country decided to use an MCB as an isolator.

 

[stillp]

There are load-limiting circuit-breakers that will reclose when the circuit load reduces. I don't think they're permitted in the UK though.

 

[Spark123]

If proper risk assessments are carried out I don't see why we can't use them.

 

[PBC_1966]

It's also interesting that, if the figures in the above link are to be believed, the average domestic electricity consumption in France (6,400 kWh/year) is about 39% higher than the figure given for the UK (4,600 kWh/year), despite the French price structure.

I have a feeling that the proportion of homes in France with all-electric heating is probably somewhat higher than in Britain. It's over 15 years since I was last there, but it certainly seemed to be the case then. And as one moves south in the country, I imagine that these days there's a little more demand for cooling in the summer than in Britain too.

 

[JohnW2]

There are load-limiting circuit-breakers that will reclose when the circuit load reduces. I don't think they're permitted in the UK though.

That's interesting. How do they monitor the size of the load whilst they are open? - if they do that with low voltage/current (e.g. putting a resistor in the feed to the circuit), I can see that 'going wrong' with some types of load!

Kind Regards, John