Electricity Generator(s): advice & help selecting

It is a bad idea not to call an electrician and have the job done professionaly.

I recently had a quote for a manual switch-over switch supplied and installed at R1500.

When the power is down, one would start the gennie, switch over the switch to gennie.

When the power is restored, a buzzer on the switch goes off, and one could just flip the switch again to mains, and kill the gennie.

But one needs decent UPS's on sensitive equipment like PC's.


mxit_fan said:
Hi guys, just bought a Ellies Silent Diesel Motor Generator - 5 or 5.5 kVA similar to the one here http://www.ellies.co.za/v2/index.php?id=724

Now how do i go about connecting this?

I've heard you can turn off all switches on your mains and run a plug from the generator to one of the plugs in the house and this will provide power to all other plugs in the house creating a circuit...however this does not sound safe, nor a very permanant solution..

How are you guys connecting these generators? Should i call an electrician rather?

Another thing is that i want the generator to switch on automatically when the power goes. How would i go about doing this?

The guy i bought it from said something about a DV board or ATS board or something which i would have to purchase in order to achieve this with this generator (follow link above). How exactly does it work?

Thanks for any help/tips...
Click to expand...
 
Beware of noisy generators

Somewhere in this thread mention was made of new regulations coming regarding noise levels. After some digging I found this interesting matrix regarding noise levels produced by Honda generators. Compare to this Jetman generator for instance, which produces a whopping 90dB compared to 70dB for a similar speced Honda! The Honda EU series produces only 59dB noise but the smallest one starts at R7000! I can imagine that with thousand of generators running all over the neighborhood in the near future there must be regulations and inspections to control the noise level.
 
Dear Acidburn21

The are available from Makro. I am currently looking at the 2KW Friman. How loud is it and have you grounded it.

Thanks

Lion66
 
Generators - the lowdown

We installed an 85Kva Gennie at work (3-phase) last year, and I installed a 40Kva 3-phase at home, so I have a bit more experience than all the newbies - here's the lowdown:

1. Capacity - You need a generator to run at around 80% load for peak efficiency and reliable operation, so if you need 5kw power, buy a 6kw generator.

2.Any generator under R 5,000 is generally crap and will not be able to run more than a single device using an element (such as oven, kettle etc).

3. Purchasing from a department store is wonderful, but who's gonna fix it when it has a problem ?

4. Cheap Gennies don't have good power regulation so you need a line filter + UPS.

5. Connecting direct to your DB board or even to the line bringing current to the house is best, but not always possible. You will have to manually switch off circuits like your geyser to prevent the smaller gennie from overloading.

6. You need an Auto transfer circuit to switch the gen on automatically when the mains power dies - on cheaper units this is an optional extra.

7. Petrol Gennies are cheap to buy, but expensive to run, and are not suited to long outages (which is what we will get in winter).

8. Diesel gennies are far better than petrol, are more efficient, and last longer. They can also run longer, but are noisier.

9. If you can afford it buy a 20Kva Diesel 3-phase gennie (from 5Kva to 10Kva there's a huge jump in price, but from 10 to 20 it's low). A 20Kva should cost around R 35,00 to R 40,000. This is a long term investment - think about what your life or the life of your family is worth. No power = no security.

10. Fumes - you need to vent the fumes - especially from a petrol gennie - exposure to these fumes can lead to death.

11. Noise - if you don't want to get sued by your neighbors, the noise at their "bedroom" at night should not exceed 35db.

12. People who sell generators are generally either deaf or liars, because they will tell you a 70db noise is "silent", when if you actually use it at night, it sounds like a 747 coming in for a landing on your roof !

13. There are 3 components to the noise:

a) The noise of the motor itself - tackled by putting the engine in a
housing.

b) The exhaust - baffles on the exhaust port to "break" the sound
waves, or running the exhaust through a water drum - but then
you have additional vibrational noise to contend with.

c) Low bass noise - vibrational from the engine thumping against
the ground - need to put layers of rubber damping between
gennie and ground - but can't get rid of this completely.

Sometimes (as in my case), we had to put the generator with it's "SILENT" housing (which is not silent unless you're deaf), inside a larger housing, which reduces the noise to a sub-bass throb (vibrational noise), but then you need to add extra exhaust fans to the housing the keep the unit cool, otherwise the unit overheats, and shuts down.

14. Keep a couple of Jerry cans of additional fuel handy. The local petrol station can't pump fuel for you if they have no power.

That should more or less cover everything.

If anyone needs specific info they can PM me - I don't sell generators (yet), but I found out the hard way that in this game the experts usually talk ****.
 
Anyone have a good source for a 20KVa units. that size would suit me just fine. Are their any petrol units at around that size?
 
Just my 10cents about Generators and UPS's. We Bought a 5KVA generator with AVR etc. Attaching a general household UPS to it is not a good idea. we did a bit of reasearch on it after we had problems connection a normal 500VA to it.

There a 2 kinds of UPS's. Online and Offline.

ONLINE: Continuously powers the protected load from its reserves, while simultaneously replenishing the reserves from the AC power.

OFFLINE: Remains idle until a power failure occurs, and then switches from utility power to its own power source, ALMOST instantaneously.

Thus, when an "offline" UPS switches to reserve power it causes some sort of frequency (Hz) glitch that causes the generator and the UPS not to work in sync, which causes all kinds of chaos.

So, when you decide you want to run a UPS on a generator, make sure you've got the "online" type. They are quite a bit more expensive, but with good reason. We learned the hard way.
 
It has something to do with frequency variations. A offline UPS depends on the battery power to overcome frequency fluctuations, so you will see that once you put some load on the generator, that the UPS will switch between AC and battery to compensate for the fluctuation and keeping the power coming out of it stable. This drains the battery very quickly and your UPS shuts down. Leaving whatever is connected to it without power.

An online UPS overcomes this by not having to depend on the input power to keep the output stable.

We connected a PC to the UPS, but as soon as we connect anything else to the circuit it causes power fluctuations the UPS did not find friendly, thus compensating for it using its reserves. These fluctuations seem to occur very often, and drains the battery backup eventually. You can see and hear this on the UPS. It keeps switching from the "AC" to "On Battery" LED and back again over and over again, at random intervals.

This is a "APC 500VA" by the way. When you read at the bottom it says: "NOTICE: The output of this device is not sinusoidal. It has a total harmonic distortion of 40% and a maximum single harmonic of 30%."
 
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I don't understand what the fuss is about when it comes to generators and UPSes.

We run a 2.5Kva genny, a Honda unit (not from Makro- from Honda SA - they are different units) and 6 UPSes(http://www.sybaritic.co.za/store/product_info.php?cPath=150_151&products_id=1096)
and we have no issues at all. This keeps our Pcs up when the power is down. Thats all a smaller office needs.

Perhaps it the quality of the AVR on the genny. Honda did say that the AVR of their unit was of a better quality. I thought it was sales talk but maybe they were right.

Make sure you buy a good genny with a decent AVR and you should have no problems.:)
 
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Well, the genny we bought is a Honda EP5000CX with EVR. UPS/Generator problems is well documented. Try googling it, you'll be surprised. The ones you use are indeed line-interactive, so the will not cause problems. Thanks for pointing that out HaNsA.
 
Thanks. Im definately going to order one of those line-interactive ones you have. Their price is quite good too.
 
Has anyone looked at the running costs of gennies? As in how many kWh you get per liter of fuel for various gennies, like a 3kW petrol version versus a 5kW diesel etc.
 
Generally speaking the petrol units are the way to go below +- 8KVA.

They are much cheaper to buy. You have run a diesel very, very long to recoup the cost savings of the more economical diesel. Of course if the electricity supply is out for a months at a time then the diesel has an advantage.
 
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