Contracted power for Households 3

[rubron]

Maybe someone who works in a distribution operator/company can clarify the following to me?

A household connected to a LV grid get a contract based on the peak power they are expected to consumed. I guess, the operator estimated the power in the number of people living in the household, or if the user in the household have a special requirement (otherwise they might get a "default" power, perhaps around 4kVA?). So once the estimated power is set for a particular household, that power is reflect in the contract, so that if someone needs high power, higher must be the tariff. So, when the power is defined. How does the distributor company/operator make sure their clients consume what they said. For example, if one contract power for 4kW and then, they connect loads that account for 8kW. How the operators make sure this does not happen, not only for one, but for all the household connected into his grid. I thought, that the way for the operator does to avoid it is by the protection installed in the energy meter? First, is there a protection in the energy meter? if I increase the power at my house, I shall let the company know so that they reset the protection in the energy meter of my house, or perhaps install a new one?

I would appreciate any hint on the matter.

 

[crshears]

Where I live, customers simply stipulate the current capacity of the power supply to be installed in the residence, with no specification or burden being placed upon the customer as to how much electrical energy they must consume. Residential meters, whether electromechanical or "smart," do not typically have a demand tracking feature.

Where I live, "load limiters" that the customer could reset were previously used only temporarily in situations where the customer was in arrears on their power bill during the cold winter months; if too much power were drawn from the grid, the load limiter would trip and interrupt the power supply to the customer, whereupon the customer would have to switch off all major loads within the residence before the load limiter could be reset. This approach is no longer followed, as the expense involved with installing and removing these devices became prohibitive; nowadays our customers are not interrupted or limited at all during the cold winter months, but if the bill has not been paid up by the arrival of summer that customer's power is completely disconnected for non-payment.

Perhaps in areas where the grid is fragile, such individual load limiters could be used; but it is my suspicion that because there would be a lot of them, the power company would want to use customer-resettable load limiters, since they would not want to have to be constantly sending out staff to perform load limiter resets...and where such fragile grids are used the technology to communicate a reset impulse from a central office to individual customers is not likely to be installed.

Just my thoughts.



CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

 

[rubron]

"nowadays our customers are not interrupted or limited at all during the cold winter months"

Say a distribution cable feed 8 costumers(households). If there is unlimited power usage by the costumer, how do the operator prevent that the power used by all the costumers (perhaps coincide at their peak at some points) burn/stress the cable. What is the criteria for sizing the cable if at last, "any power" is allowed to the costumers?

 

[crshears]

Cable size = sum of total connected households x diversity factor...

If customers are interrupted for, say eight hours, then power is restored, all customers might draw the maximum power available until demand loads are satisfied [ this we call "cold load pick-up" ]. Once refrigerators and freezers have cooled down to normal controlled temperature range, oil furnaces or electric heaters have warmed the houses back up, etc., etc., the normal "random" load cycling resumes. The inverse current / time characteristic of the supply conductor is chosen / are so sized/rated as to meet this limited time extra demand without sustaining damage.

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

 

[Parchie]

To add, cold winter months have a positive effect on cable current-carrying capacities, so one need not worry about lines getting too hot when loaded beyond normal design loads!

 

[waross]

In our rural area, there is demand billing.
The utility sets the demand but may respond to arguments from the customer.
The basic household demand is 5 KVA.
With a shop and a barn the utility will suggest a demand of 10 KVA. With more equipment installed they may require a higher demand.
I have a barn and a shop, but when I pointed out that I have only a few lights in each building, I was allowed to use a 5 KVA demand.

How does it work?
I pay a demand charge each month based on 5 KVA demand in addition to the consumption charge and other charges.
The utility installs a demand breaker at the meter.
If the demand breaker trips, I may reset it.
For a 5 KVA demand the utility installs a generous 35 amp rated breaker.
In about 10 years of living behind a 5 KVA demand breaker I have had the demand breaker trip only once.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[rubron]

@waross

35A for a three-phase system 400V would be 24kVA. So they installed at the meter a 35A to trip if you exceed 24kVA have a contract of 5kVA?

Other thing, how can you access to the breaker of the energy meet if that is supposed to be inaccessible by other except the electricity supplier?

 

[waross]

Assumptions will bite you.
It is not three phase, 400 Volts. It is single phase 240 volts. 35 Amps x 240 Volts = 8.4 KVA, generous but less than 10 KVA, the next available demand.
The breaker is mounted in a compartment with a tamper resistant seal. The handle is accessible to reset, but the breaker itself is not accessible without breaking the seal.
That is, you can reset a tripped breaker or turn the power off but you cannot access the connections to install an illegal jumper.

Other thing, how can you access to the breaker of the energy meet if that is supposed to be inaccessible by other except the electricity supplier?

Did I imply that? Sorry.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[itsmoked]

Perfect application for a powerwall.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[waross]

Well Keith, my fixed costs are about twice my consumption costs. As long as I have to have a grid connection it isn't worth considering alternate energy.
The government wants to promote green energy but the power companies manage to justify making it unrealistically expensive.
I am considering building a retirement home in another jurisdiction where solar power is more economically friendly.
Instead of a power wall you can use the grid to bank power. Your are only charged for your net use.
Fixed costs are reasonable.
Any overproduction will be paid for at wholesale rates.
No small producer will get rich selling solar energy at wholesale prices, but you can reduce or eliminate your monthly consumption charges.
Still in the planning stages. Stay tuned.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[itsmoked]

Bill we should take this discussion to its own thread, we could have some fun with it. I wasn't talking about solar in this case only having a small faucet to fill up a pool day and night so you could get as much water as you want anytime you need it. Not to mention having it when the water is cut off entirely.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[rubron]

@waross

Sorry for my assumptions and thank you for the explanation.

-"less than 10 KVA, the next available demand." so from 5kVA it jump to 10kVA to the power one can contract? Do you have some info or reference of those available demand? I guess it- would depend on the distribution operator.

-Say you want to increase your demand to 12kVA, then the electricity supplier would have to change your meter, do you have an idea what would be the new current limit of the meter?

If I would have to buy/install energy meter for households, thinking of the lifetime of those meter of 20 years? I would install a meter with relatively huge capacity(may be expensive, but in long term may be more convenient) so that if users in the grid ask me for higher demands I would not have to change the meters already installed.

 

[waross]

At one location I had a 100 Amp service and a 100 Amp meter. The utility installed a 35 Amp demand breaker.
At my present location I have a 200 Amp service and a 200 Amp meter. The utility installed a 35 Amp demand breaker.
If I request a 10 KVA demand, the Utility will change the breaker.
The next step is 15 KVA.
The service size is based on square footage and installed appliances. Do you cook, heat water, dry laundry, heat the dwelling, A/C etc. with gas or electricity?
My 2640 Square foot shop has a code stipulated demand of 13200 Watts or 55 Amps at 240 Volts. The actual load is less than 200 Watts of LED lights.
Doing the code calculations for the minimum size service I must use the 13,200 Watt figure, added to the dwelling load.
The occasional use of lights in the shop has little impact on the demand breaker.

Do you have some info or reference of those available demand? I guess it- would depend on the distribution operator.

In my case I would Google Atco tariffs in Alberta Canada or just phone customer service.
Contact your local utility for their requirements.
Interestingly, I visited Chile many years ago. The places that i visited also used a "demand" breaker. It was also a GFI breaker protecting the entire building at, if I remember correctly, 30 mA.
Is there anyone here from Chile? What is the present practice?

Bill
--------------------
"Why not the best?"
Jimmy Carter