Grid Frequency and Voltage in South Africa

South Africa's local distribution is 11 kV. Domestic electricity is 240 Volts (commonly referred to as 220 volts). Frequency is 50 Hz.

Voltage and frequency do not vary across the country (not deliberately anyway).

Thank you! So, the domestic electricity which is relavant to our equipment(the inverter) is 240V rated, not 220V, if I get it right.

That also means, we have to switch the output power voltage of our inverter to be 240v from 220v. Is that right?

In all, what is the difference between 200v and 240v when we talk about the rated grid voltage in SA?

BTW, I check www.eskom.co.za, but failed to find relavant information.

Thank you!

Also look at the ESKOM site for more information - www.eskom.co.za

First you need to decide if you are referring to the 3 phase distribution voltage or the single phase level (phase to neutral). Officially, SA is now like most other countries, 400V 50Hz 3 phase, which makes the single phase voltage 230V. In days gone by, the single phase used in homes was 220V, but like most IEC countries, they officially changed to 230V because that fits within a 10% tolerance of older 220V appliances and newer 240V rated equipment from other countries.

Voltage chart for world distribution systems

Thank you!

Then the first thing I will do is to check with my distributor whether he has connected te inverter to V3 or V1.

If he connects to V1, I think our inverter with rated voltage in 220V is viable. Then there might be some other problems. maybe he wrongly connect the plugs. I don't know but I will check.

Appreciated!

I am not an electrical engineer, but I thought that South Africa was on 415 Volts 3 phase and 240 single. In the old days the Eastern Cape used to be slightly higher but I can not remember details. Have not lived in SA for some years now so hopefully somebody there will clear this up.

Hi all,

In SA frequency stays 50Hz throughout.

Most Eskom (Eishkom to the locals) power stations generate electricity at 22 000 volts (3 phase 50Hz). To transmit this power over long distances, Eskom steps up the power to to the following voltages for transmission: 220kV; 275kV; 400kV or 765kV. This electricity now goes into our national grid.

When it gets to the end user it is stepped down. This could be 11kV for a large factory or 400V(380V) for shops/homes. If you take a phase to neutral (single phase voltage) i.e. 400/sqrt(3) you will get 230V single phase @ 50Hz.

Some end users (Sasol) use vast amounts of power. They get supplied at 132kV 3 phase. Our railways also use quite a bit of power. They operate at 25kV and 50kV respectively.

Our plug sockets at home are single phase 230VAC 50Hz. As you can see from above this is very different from the grid voltage, but the frequency throughout stays the same.

This frequency is the same throughout Africa. The only people I am aware of that are on a different frequency is the US of A. They have a 60 Hz system.

I hope this helps answer your question.

Regards,

Craig

Hi, Craig

The answer can't be any more clear. Great!

Thank you!

Rgds.

Ani-Luo

I would recommend that you get the customer to specify exactly what they need. Although you have been given some information here, an internet forum is not a reliable source (no disrespect intended towards other contributors in the the thread) from a business perspective. ESKOM is the primary supplier of electricity here, but perhaps you should also try and contact NERSA (National energy Regulator of South Africa).

Thank you!

Some good posts here, but one question does not seem to have been addressed as of this moment.

That question being that in most countries, such equipment has to be built to a specific standard and to be tested and certified by the country in question, before being sold to any customers......this is intended to safeguard EVERYONE involved....

Therefore, if this procedure is followed, you should not need to be asking such questions on CR4...you will have all the correct answers to hand.

...as you will already know all the answers and have a certificate that proves that it is safe in all areas.......and may be sold and installed.....even this cannot prevent ALL accidents, but not even getting the voltage correct implies a complete disregard for safety......

Maybe I am off base here, but I am thinking of safety first. If your equipment kills somebody or sets fire to a house, then there might be some major legal problems at the highest levels. Take this seriously....

We on CR4 love questions, the more the merrier, and we love to be informed as well....but PLEASE PLEASE play safe in all areas......

Thank you, Andy! One thing i have to clear out here is that there isn't any damage caused by our products till now. And we have the CE certificate which is a EU standard. If you have interest, maybe you can find some relative articles about CE.

And the problem we are discussing is that our customer reported that he couldn't connect the wind turbines on the local grid, which I have communicated with him and will report here once it is completely solved.

I understand that you have such a safety concern. Maybe I have to offer the whole story. We thought that the grid voltage and frequency in SA is 220V, 50HZ and it was confirmed by our customer. So we set the controlling systems accordingly. Now there is such a problem of being unable to connect with the local grid. So the first idea comes into my mind is that maybe the voltage and freqency of the SA is not 220V,50HZ. And I come here and get kind tips from you all. Thank you!

I have offered my suggestions to our customer,and is waiting for his comment.

I'm sure it can be solved.

B/rgds.

Ani-Luo

But you imply that your equipment has NOT been certified for SA, just for Europe.

(I thought that SA had the same standards with voltage etc., but I could be wrong!)

By the way, Europe is nominal 240-220v, (as far as I remember!) but you usually see only 230v or less on a meter. You may be seeing a higher voltage than you are supplying......

Here it suggests the same values:-

http://en.wikipedia.org/wiki/Domestic_AC_power_plugs_and_sockets

To supply the grid, you need to go "Online" at a slightly higher voltage and a tiny bit faster frequency, so that you "take Load".

Going online with less will always drop "good equipment" offline immediately.

Badly designed equipment might even "Motor!" and push up your electricity bill even more!!!

The further this discussion goes, the more it seems that not sufficient planning has gone into the acquisition process. Perhaps it is time to call in the services of an engineering consultant. Neither manufacturer nor client appear to have the relevant knowledge/experience to implement the system safley and efficiently. This is not the kind of project one should tackle without prior experience/expertise, IMHO.

Hi Ani-Luo

In SA a trader may be required to register with the energy regulator

except for Demonstrations , own use an off grid systems all generation, transmission and distribution require a license.

The Electricity regulator will supply detail on request.

All systems must comply with regulations , rules , code of conduct and guidelines made in terms of the Act.

Selling is learning and I confess that I failed in doing enough homework before selling our products to SA customers. However, from the information I got b4, the voltage and frequency in SA was really 220V, 50HZ. Now from the opinions got from here, I'm better equipped to discuss with my customer on this seriously!

About the equipment safety concern, Yes, it's important. Electricity is something EVERYBODY has to take with great care. That's why we don't allow customers without relevant professional knowledge and skills to install our wind turbines.

As per certificate,we don't have any for SA market, but at the mean time, our cusotmer didn't ask us for it. Otherwise, we couldn't have sold to him.

One more important thing is that, 80% of our products are exported to about 70 countries, and till now, there is no accidents on safety happening. However, it doesn't mean accidents won't happen. Take care always!

There is no bad opinion here, there is only different ones. I appreciate all of the posts.

But if anybody who wants to have a deep discussion, one suggestion from me is that he/she absorbs some knowledge on small scale wind turbines.

Small scale wind turbines is very popular recently and it will bocome even more popular. Now at time of global economic crisis, many many countries have got great interest in renewable energy like wind,as the oil price is crazily high!

And another news is that, Windsave company from Scotland has signed with SA an order of small wind turbines which will be planted in outskirts of Cape Town with an amount of $19,000,000 (http://wind4africa.net/news/viewnews.php?ID=442)\

it's good business and very very promising. It is worth learning something about wind turbines.

Rgds.

Ani-Luo

(Skype:Ani-windturbine, Email/MSN:hummer-607@hotmail.com, Web:www.chinahummer.cn/eng)

Hi all,

I think we are confusing the issue here.

Firstly there is no 220VAC grid in SA.

We get our distribution (local plug outlets in our homes/offices etc) from three phase 400 VAC. They take a phase and neutral which gives you 230VAC. The phases are balanced for load. This is stepped down from the local grid in various stages as mentioned in a previous post.

You will never be able to push your 220VAC back into our grid.

To get back into our grid (I think your turbines generate +-250kVA) you would need to have at least 3 phase 400V (380V). You can then syhnchronise your generators. Then step up the power to 11kV and then synchronise to the distribution grid.

But with 220VAC single phase - you will never get anywhere.

Perhaps you need to supply us with more information. Is this turbine intended only to supply a single household? Or are you trying to actually provide power for a local district?

Either way, I suggest you get in touch with a local consulting firm as they are in a better position to help you out.

I would reccomend you get in touch with the company I work for as we are an E&I consulting firm: www.ehl.co.za and deal with the power generation company on a daily basis.

Regards,

Craig

Hi,

it's impressive that so many of you have taken part in the discussion. Thank you!

I have posted in another thread "Wind turbine installation in SA" some information about our equipments.

They are only for private house or a small community use, not for a district.

And they are to be connected into single-phase grid, and the output voltage can be adjusted as per the local situation.

If you are interested in our products, pls. send specific email into my private mail box. It is: hummer-607@hotmail.com

Or you can join Skype with me. Mine Skype Id is Ani-windturbine

BTW, you company's web can't be opened now, but I will try later.

B/Rgds.

Ani-Luo

Hi there,

That makes much more sense then.

But there can be no synchronization. It is a either or situation. Either your turbine supplies the house or Eskom. You will need to make sure that you use interlocking contactors.

If you want to supply the house then Eskom must be switched out and visa versa.

Regards,

Craig

Hi Craig,

Currently Eskom (state owned company) has a total installed generating capacity of some 42,000MW (net 36,200 MW, peak 34,200 MW) with already new peak capacity in demand since 2007. 93% of its power production capacity is of coal based (10 large plants), 5% nuclear and 2% hydroelectric. We help the local people to produce electricity for daily use by themselves with wind energy. Besides, they can also sell the power to companies like ESKOM, with our on-grid wind turbines. The feed-in tarriff in SA is about $0.14/KWH. ( To be honest, it is far less than in other countries.)

SA is rich in energy, but it also a large energy consuming country. Reportedly, most of SA's energy is produced from coal which causes a lot of CO2 emission.

In the meantime, SA is a country with long coast line and thus rich in wind energy, especially alongside the coast. Wind energy is clean and renewable energy. If more and more SA residents and communities use the wind energy, it will be both a good source of power and a way to avoid pollution.

Image, if there is an average local wind speed at about 3 meters/ second, then you can generate power with wind turbines and don't need to buy electricity any longer.

It seems that we have to change the name of the thread

Rgds.

Ani-Luo

Table-Bay - That is also called the Cape of Storms.

Once I were sure the people are leaning forward at 45deg when walking against the wind.

I have heard of empty oil barrels blown up the cliff on the other side of the peninsula.

Would your windmill last?

Hi Hendrik，

Our wind turbine has a start-up wind speed of 2.5m/s or 3m/s

and the rated wind speed is 6.5m/s:350W,7m/s:500W,9m/s:1000W,9m/s:2000W,10m/s:3000W,10m/s:5000W, 10m/s:10kw, 10m/s:20KW

safety wind speed is 25-30m/s

When the wind is too strong, if there is no protection, the blades will rotate very fast and the system might burn out. But don't worry, our wind turbines have high speed protection. When the wind is too strong, the blades can stop rotating immediately with short circuit or turn its direction with intelligent control system to avoid facing the wind directly.

FYI

B/Rgds.

Ani-Luo

Not quite right.

If the wind turbine can supply, it will reduce the load on the local transformer and supply at least part of the load for those 3 phases. (I am fairly sure that a single phase system will be similar, but for one phase only, though I personally have no relevant single phase knowledge in this area to draw on!)

The frequency of the local supply will "lock-in" the Wind turbine to that frequency. The turbine cannot supply enough load to change the frequency at any point....theoretically, it does happen, but what the effect is is that load is shed from once source and taken on by the other....I gues thoretically, it could be possible that a turbine supplies the whole district and "back feeds" through the transformer.......but I would like someone with more explicit infos to chime in here before I put my foot in my mouth!!

The frequency of the local supply will "lock-in" the Wind turbine to that frequency. The turbine cannot supply enough load to change the frequency at any point...

I well remember this demonstrated to our class the one time I was in a heavy current lab at Cape Technikon (now CPUT). A small 3-phase generator was running, and the reed frequency meter was indicating that it was just below 50Hz. The main grid was spot on. I winced as I realised that the lecturer was about to throw the switch. And I was even more skeptical when he announced that "we are now supplying power to ESKOM*". He told us that the two systems were automatically synchronised when connected. It made quite an impression on me to this day.

*the main electricity supplier here

Did it immediately "drop off" as good equipment should? There is a unit we called the "reverse power relay" (40 years ago!!) that would take the contactor to an off position immediately.

The phase angle needs to be watched as well, even as little as a 7 degree "out of phase condition" can be felt through the ship's structure.....it does not do the gennies much good either.....

I did see some photos of a ship where they paralleled two gennies "out of phase", one tried to leave the ship and "skipped off its holding down bolts!!!! Luckily nobody was "in the way" at the time.....maybe the pictures can be googled....

Did it immediately "drop off" as good equipment should? There is a unit we called the "reverse power relay" (40 years ago!!) that would take the contactor to an off position immediately.

I'm afraid I did not pay attention to those details (I was not a HC major).

Hi there,

Yes the cape is ideal for wind farms.

If you wanted to sell the power back to Eskom though, you would need to do a lot more. Higher voltage, synchronization etc.

I know that there is some talk of this going on, but I am not up to date with it.

Good luck with your endeavor though, and if you need any help with E&I in Africa, don't hesitate to contact us.

Regards,

Craig

Hi Ani-Luo

Our Energy Regulation Act only came into effect in 2006 and we are therefore in a transitional period at present. Many of the rural and farmer communities does not really know about it yet.

What you have done up to now (selling to private users) most probably are perfectly legal. I haven't checked if relevant regulations are in place yet but I do suspect that it will be close to the EU code.

As for 220Volt / 50 cycle there are currently a lot of private gen sets running on that specifications and it would be absurd to declare all of those illegal.

The grid in SA is also in an expanding mode and there may still be municipalities supplying 220volt as well. (about 8 months ago I did measure 220V in a small rural town) A short wile ago there were even 110V DC available.

Most of our existing railways runs on DC traction but the new Rapid Rail Link will run on AC.

Connecting to the grid is another story.

I will however investigate and inform you on your PM.

What a country!

Hi all,

Connecting to Eskom's grid can be and is done. But not on 220VAC. Sasol does this but at 132kV. They actually sell their electricity back to Eskom.

If you wanted to connect to the grid you would have to be at a much higher voltage and you would have to synchronise your turbines to the actual frequency at that time.

There is no law against having your own genset - the problem comes in with the protection method. You cannot synchronise your home genset (220VAC single phase) back to eskom for obvious reasons.

If you were to step up your voltage to at least 11kV and you had a three phase output and you had the syhnchronizing pannels and you had load control - this can be done and as far as I know this is what they are trying to achieve with the wind farms down in the Cape (Darling I think).

Regards,

Craig

Hi all

Let me introduce you to Ani-Luo's typical customer.

Sheep farmer on 10000 ha of Karroo farm.

5km from end to end.

Using reciprocating action windmill for pumping water from boreholes for watering the animal (for ages already.

At the homestead the power requirements are minimal.

Anthracite stove for cooking (and they do cook) and heating of water. Desert cooler.

Lights , radio, etc running on batteries charged by solar panel and maybe a 500 W wind charger.

Maybe a inverter to run some 220v appliances like a Marnitz radio for security.

A 220volt 5kw gen set used for powering power tools, meat cutter, small lathe etc. (average running 40hours per year).

25 km from the nearest grid connection.

What more could he want.

Local Grid customers

5 or 6 farmers coming together and bought a second hand Blackstone slow running (600RPM) diesel gen set (220volt/50cycles) They would do good to get a wind charger (with proper isolation).

Small one horse towns and settlements generating own electricity.

Informal settlements (squatters)

Thank you, Hendrik!

Our wind turbines are very good equipments for powering the irrigation system.

It has 15 to 20 years life circle.

For the off-grid system, the wind turbines are connected with batteries and charge the batteries first. Then, the inverter will change the batteries DC voltage into AC and output.

For the on-grid system, there are no batteries. The controlling system will connect with grid directly. With intelligent system, it can work very well.

Rgds.

Ani-Luo