Losing excessive electricity

[Fudzy]

Nope using gas heaters, the reason I say that the Conlog meter isn't working properly is because I have an Eddie unit that displays the amount of electricity being used at any given time.

For example if a bath has been run the Eddie unit shows the geyser unit using about 3400 watts heating the water up again where the Conlog prepaid meter shows no activity what so ever, the same happens in reverse where the Eddie unit will show about 240 watts being used and the prepaid meter will show 2-3 bars.

I'm currently going through +\- 30 prepaid units a day which seems quite heavy.

Have you contacted CoCT?

http://www.capetown.gov.za/en/electricity/Pages/ContactNumbers.aspx

 

[JohnHay]

Pretty good values. Are you able to tell us what the voltage range was as well? Nothing to do with where you work I suppose?
Speaks for very good power regulation.
Geoff D

As far as I know the whole country is synchronised so the frequency should be the same anywhere on the grid. The voltages are less easy to compare because it depends on the transformers and the different areas might run at different voltages.

 

[oober]

Starting to think I need a relay before the main switch that keeps the power off an extra 10 minutes after an outage or something, manually doing this is becoming a pain, any of our electricians care to comment on legal possibilities for that?

Luckily my inverter has a changeable reconnect timeout, so it only reconnects after 1 min when the power comes back on. You can actually hear the contactor switching inside, since it's quite loud.

 

[Geoff.D]

As far as I know the whole country is synchronised so the frequency should be the same anywhere on the grid. The voltages are less easy to compare because it depends on the transformers and the different areas might run at different voltages.

Correct, it is a little bit difficult to conceive of a situation where the frequency would be different anywhere on the grid. -- the frequency should vary equally everywhere.

What did you get re - voltages? I am pretty close to where you are, certainly fed from the same main power lines and transformer points that you are on? My voltage measurements are all on the high side ( above 237V single phase RMS).

 

[JohnHay]

Correct, it is a little bit difficult to conceive of a situation where the frequency would be different anywhere on the grid. -- the frequency should vary equally everywhere.

Voltage you mean? I do not think voltage will vary exactly the same everywhere. Local loads that are changing will have a bigger influence on the the local voltage than elsewhere?

What did you get re - voltages? I am pretty close to where you are, certainly fed from the same main power lines and transformer points that you are on? My voltage measurements are all on the high side ( above 237V single phase RMS).

At home I also see 237V often, but it varies between 230V and 240V. At work I see a lower voltage, but understand from the electricians that our transformers are lower than the rest of the city.

 

[Sonic2k]

Frequency deviation downwards is an indication of an impending trip or serious problem.

Modern digital ripple receivers are programmed to detect this and disconnect load immediately.

As for the above info, it was confirmed to me personally by Eskom some years ago.....

 

[Geoff.D]

Frequency deviation downwards is an indication of an impending trip or serious problem.

Modern digital ripple receivers are programmed to detect this and disconnect load immediately.

As for the above info, it was confirmed to me personally by Eskom some years ago.....

Frequency stability is important for all induction motors and compressors. A drop in frequency indicates an increase in load, which is not being matched with an increase in supply.

Resistive loads such as for geysers etc, are not so bothered by a change in frequency. Invertors and UPs units are also not too happy with a change in frequency.

 

[Geoff.D]

Voltage you mean? I do not think voltage will vary exactly the same everywhere. Local loads that are changing will have a bigger influence on the the local voltage than elsewhere?

No I meant Frequency.

At home I also see 237V often, but it varies between 230V and 240V. At work I see a lower voltage, but understand from the electricians that our transformers are lower than the rest of the city.

Helps when you work in an environment with "special conditions and requirements"
[three independent incoming feeds with special transformer points, and special conditions re LS as well! ]

 

[DollyAAAA]

Frequency stability is important for all induction motors and compressors. A drop in frequency indicates an increase in load, which is not being matched with an increase in supply.

Resistive loads such as for geysers etc, are not so bothered by a change in frequency. Invertors and UPs units are also not too happy with a change in frequency.

You could even go so far as feeding your geyser element directly with a PV panel (DC) - with reasonable voltages of course. It's just a dumb resistor.

 

[richjdavies]

You could even go so far as feeding your geyser element directly with a PV panel (DC)

Just so that others' don't get the wrong end of the stick here - the only reason to use Solar-PV to heat-up water would be if it's producing spare power; otherwise it's horribly wasteful.

If you're using silicon to convert light energy into electrical energy to convert it into chemical energy, then back into electrical energy, then back into heat-energy; then you're doing it wrong.

For the numbers a solar PV can produce around 150W/m2* at peak - so on a sunny day you'll get around 3-4 hours of production = around 0.5kWh of energy.
That's enough to heat about 8 litres of water...(from 20 degrees to 70 degrees) or about 40 seconds of a shower...

In a 200L geyser that much energy will the same as heating it up by around 2 degrees-C.

Conversely a solar-water-heater will capture about 4 times that amount of energy...

Sorry for the Rant - I've seen a few rather dishonest sales people encourage people to buy some weird geyser-heating installations, and I don't think they even knew what they were selling; let alone what it would mean for the end-users.

*- based on http://www.sustainable.co.za/renesola-virtus-ii-300w-solar-panel.html

 

[DollyAAAA]

Just so that others' don't get the wrong end of the stick here - the only reason to use Solar-PV to heat-up water would be if it's producing spare power; otherwise it's horribly wasteful.

Yes, I wasn't suggesting people do that, or that's it's even a good idea, just that you COULD do it. It was a comment flowing from the frequency intolerance part of the conversation.

 

[Geoff.D]

Spot on ! Excellent post. yes we are bombarded with scam artists these days.

I have great fun with them, I let them tell their story and than start the interrogation, And the more persons in the audience the more I enjoy it!



Solar direct to heat for water is the best it can get.
Solar direct to electric is also the best

Then we start to compromise as you have indicated, each with its inherent inefficiencies and losses, some of which are unavoidable

 

[Geoff.D]

the 4 x 4 community has been though all these scenarios.

So we generally know wots wot.

TVs and many appliances are actually all DC (12V) these days.

So what we SHOULD be doing is

Solar ----> DC storage ------> straight to the appliances, LED lights etc.

What do we do because of the "rules and regulations" and because we are failing to think the thing through from a system POV is:

(1) we need STBY power ----

(2) Put in a generator to cater for our normal AC consumption --Generator connected to the main board with a change over - oops! This costs big bucks! (capital and operating, diesel costs) not to talk of noise etc, etc.

(3) Okay then we will decide what the minimum requirements are ( TVs, lights, decoders, maybe a fridge and at least a kettle)

(4) okay that is x watts of AC --- off we go and buy, generators and complicated control boards and wiring, maybe include solar STBY as well.


Instead of:

(a) water heating switch to solar or gas
(b) cooking switch to gas?
(c) refrigeration - ah well not so easy as then we have to have new fridges and freezers
(d) Air con - ah well may be we should have stuck to proper insulation double cavity walls and proper roof design he !
(e) Lighting Yes - go for LED - then we fall for the AC to DC conversion LED lamps!
(f) Entertainment --- all devices are DC so what we need is Generator - AC 220V driving an invertor - feeding DC battery storage, - feeding an invertor - 220 V - feeding a TV PS which converts it back to DC ?????

Huh?

 

[DollyAAAA]

the 4 x 4 community has been though all these scenarios.

So we generally know wots wot.

TVs and many appliances are actually all DC (12V) these days.

So what we SHOULD be doing is

Solar ----> DC storage ------> straight to the appliances, LED lights etc.

What do we do because of the "rules and regulations" and because we are failing to think the thing through from a system POV is:

(1) we need STBY power ----

(2) Put in a generator to cater for our normal AC consumption --Generator connected to the main board with a change over - oops! This costs big bucks! (capital and operating, diesel costs) not to talk of noise etc, etc.

(3) Okay then we will decide what the minimum requirements are ( TVs, lights, decoders, maybe a fridge and at least a kettle)

(4) okay that is x watts of AC --- off we go and buy, generators and complicated control boards and wiring, maybe include solar STBY as well.


Instead of:

(a) water heating switch to solar or gas
(b) cooking switch to gas?
(c) refrigeration - ah well not so easy as then we have to have new fridges and freezers
(d) Air con - ah well may be we should have stuck to proper insulation double cavity walls and proper roof design he !
(e) Lighting Yes - go for LED - then we fall for the AC to DC conversion LED lamps!
(f) Entertainment --- all devices are DC so what we need is Generator - AC 220V driving an invertor - feeding DC battery storage, - feeding an invertor - 220 V - feeding a TV PS which converts it back to DC ?????

Huh?

Not so cut & dry.

A lot of electronic appliances do have power supplies that convert the AC to DC internally to various voltages - not just 12V. Problem is, you can't just buy a fancy TV and rip it open to supply it with DC. What will happen to the warranty? How thick are your cables going to be if you try to supply everything in your house with 12VDC? How will you run your lights if you do have Eskom? Those transformers also heat up and waste energy.

I also don't like the inefficiencies of conversion, but it is unavoidable.

 

[mmacleod]

Problem is, you can't just buy a fancy TV and rip it open to supply it with DC. What will happen to the warranty?

That part is becoming less and less of a problem (at least if you are careful when you shop).
Lots of newer LED monitors etc. now come with external power supplies instead of doing the conversion internally, replacing that with direct DC becomes a lot more viable when the power supply is external.

As "USB-PD" becomes more widespread I expect to see more of this, I don't think you will see a situation where it is common to run your whole house on DC with DC wiring throughout, but I can see a point where several of your rooms have their own big "USB power supply" device, to which most of your digital stuff will then connect and run (which could potentially be fed directly by solar for people with solar) instead of each device having its own wall wart or internal conversion.

The computer is becoming this 'power supply device' for now - its more and more common to see tons of gadgets sourcing their power through your PC, e.g. my wireless router I now power off my PC instead of having a separate plug for it, but I expect at some point that the separate purposes will be realised and it will become a seperate power supply (that the PC also draws from) instead of the PC filling the role.

 

[Sinbad]

That part is becoming less and less of a problem (at least if you are careful when you shop).
Lots of newer LED monitors etc. now come with external power supplies instead of doing the conversion internally, replacing that with direct DC becomes a lot more viable when the power supply is external.

As "USB-PB" becomes more widespread I expect to see more of this, I don't think you will see a situation where it is common to run your whole house on DC with DC wi ring throughout, but I can see a point where several of your rooms have one big "USB power supply" on which most of your digital stuff will run, instead of each device having its own wall wart or internal conversion.

an LED monitor doesn't cut it as a TV in a full sized family room setting...

 

[mmacleod]

an LED monitor doesn't cut it as a TV in a full sized family room setting...

Yeah, not what I was suggesting... Though as an aside honestly a large LED now is probably better/larger than the average TV people has not long ago, and they did okay then, so taking a step back and not being snobby about it one probably could make do just fine.

However was just giving an example of devices that used to mostly have internal power supplies until not too long ago and now have external ones increasingly often, with careful shopping you can potentially find the same thing for TVs, if not now then in future.
I wouldn't know because I don't own a TV, so I don't spend much time researching them.

 

[mmacleod]

Took about 2 seconds on google to find one - http://www.flatpanelshd.com/review.php?subaction=showfull&id=1399283987

 

[Geoff.D]

That part is becoming less and less of a problem (at least if you are careful when you shop).
Lots of newer LED monitors etc. now come with external power supplies instead of doing the conversion internally, replacing that with direct DC becomes a lot more viable when the power supply is external.

As "USB-PB" becomes more widespread I expect to see more of this, I don't think you will see a situation where it is common to run your whole house on DC with DC wiring throughout, but I can see a point where several of your rooms have their own big "USB power supply" device, to which most of your digital stuff will then connect and run (which could potentially be fed directly by solar for people with solar) instead of each device having its own wall wart or internal conversion.

The computer is becoming this 'power supply device' for now - its more and more common to see tons of gadgets sourcing their power through your PC, e.g. my wireless router I now power off my PC instead of having a separate plug for it, but I expect at some point that the separate purposes will be realised and it will become a seperate power supply (that the PC also draws from) instead of the PC filling the role.

That is how I see it as well. If we list the electronics in our homes all requiring DC power (12 - 20 V):

(1) Security systems -- mostly 12V with external Power bricks
(2) Electric Gate Motors - 12V
(3) Decoders and STBs - 12V with external bricks
(4) Flat panel TVs- all that I have seen lately have external power bricks -- most are 12 V, a few are odd
(5) Cell phone chargers - 5 V
(6) Laptops -- all over the place between 12V and 20 V
(7) LED lights -- also all over the place -- 12V, 48V
(8) Internet connectivity ( ADSL modems etc telephones) (7.5V - 12V)

 

[me_]

That is how I see it as well. If we list the electronics in our homes all requiring DC power (12 - 20 V):

(1) Security systems -- mostly 12V with external Power bricks
(2) Electric Gate Motors - 12V
(3) Decoders and STBs - 12V with external bricks
(4) Flat panel TVs- all that I have seen lately have external power bricks -- most are 12 V, a few are odd
(5) Cell phone chargers - 5 V
(6) Laptops -- all over the place between 12V and 20 V
(7) LED lights -- also all over the place -- 12V, 48V
(8) Internet connectivity ( ADSL modems etc telephones) (7.5V - 12V)

I'm no electrician so I might be wrong, but it I think about it:
I believe the standard wiring used in households is 2.5mm (this is quite thick and difficult to work with).
Lets assume that the points that you are trying to connect are 20 metres away (remember it has to go up along walls then down again) then the maximum amperage you would be able to run per wire would be approximately 9A to have a voltage drop of less than 10%.
That would mean the maximum power over 1 wire would be approximately 108 watts.

TVs, Decoders, etc are usually between 70 and 100W which means you would have to run 1 wire per component or install far thicker guage that is going to be a nightmare to work with.
A more practical approach would be for a 48VDC standard to be introduced as that would be far more efficient - +-36A for 10% voltage drop which equals 1728 watts on a single cable.
I really don't think low voltage is a good idea for distributing electricity around a house.