GENERATORS?UPS?INVERTERS?

[Dave A]

Pieter - Have you taken a voltage reading when the generator is under a steady load?

[murdock]

make sure the ups is an online one and will work with the generator...

take a look at the images of a recording i did for a short period of time on a petrol generator...37 transients occurred in matter of couple of minutes...this what kills your sensitive electronic equipment...unless some one can show you a pictures like these on their test equipment dont believe any cr*p you hear about AVR and pure sine waves...ask them to produce a recording of their generator or ups or invertor taken while running at your site or office not one they have downloaded from a web site.


be careful these are crazy times and every person his uncle and mother in law are trying to unload generators...ups and invertors...unfortunatley we the public are paying for the eskom/goverment fiasco in more ways than you know...penalties on using electricity???? interest rate hikes ...high inflation ...soon the water problems??? what next??????

you ask yourself why are we always the ones who always have to suffer for other peoples mistakes....

[deon43]

Deon

Hi all I’m new on the forum but an old hand around the block! To the question on solar equipment and the functioning of these systems for backup there are a few important factors"
1. Generators are stinking, noisy convertors of expensive fuel to noise and is very bad to our environment with the gasses they release, so if you want this and like stink air and pay like crazy for fuel, get yourself a piece of this crap!
We are from the 21st century guys and girls, didn’t you know the world has something like electronics? And who says it is expensive? Well this is a total misconception and a real argument for people that can’t do analysis over a time period, if you take a time span of one year; I bet you will be better of with a UPS Solar system!! Ya Ya there is always the guys and girls with the question marks on the forehead not understanding, so let me help a bit as this is my speciality, making power to use from the sun.

Q, Why is invertors so expensive?
A, In South Africa, ripping off people became a game and creating a total negative on some products. I’ve seen companies buying these units and good ones from abroad for about R1000-00 on a 1.5KVA pure sine wave with 93% efficiency and it’s been sold in South Africa for a small amount of R4500-00, that’s what I call a RIP OFF!!
Q, what should I be careful when buying a Inverter for
A, 1. Make dead sure this is a pure sine wave inverter as Square wave units will damage anything that has a Motor drive like a fridge and some other equipment
2. Make sure this is a good system with efficiency of at least around 90%; remember the leftover % is wasted power used
3 Make sure the unit fit for the application, for computers an online but for lighting a relay transfer will be good
4. If it is used for standby lighting or online backup make sure the Charger inside the unit (Must have one inside or you have to buy a external
One) is capable to recharge the unit batteries in at least 8 hours. External battery systems give you the advantage in making the battery capacity bigger for longer backup
5. The most Important is don’t believe all the crap people tell you about the invertors either ask real experts or learn the info yourself by getting it from the net. Inverters are and will be the better solution in backup; you can have 10 min or ten days backup, your choice, energy come from a source the bigger the source the longer the time

Any person is welcome to contact me and Il gladly give them some info, keep it short please and hi wise guys out there who knows everything, please I’m not here for arguments about how much you know but to help these who is in the dark, lately a lot by Escom, the angel of darkness, lol

[murdock]

ups solar systems...i looked into this system for some of my customers but at the time... costing and capacity were the 2 issues taken into consideration which made me consider other options...

give us some sort of ball park figue what it would cost to rig up a 2 kva system with an 8 hour run time and a charge time of 10 hours...lets say the units are 10 metres apart...how long would it take to recover from the cost of this type of installation.

i have found adverts all over the place with R75- R150 per month saving...phone your geyser...knows your geyser status...etc...etc...problem is this unit costs R2000 + installation...just to let everyone know you can buy a heineman timer with a battery reserve which has a 20 amp switching relay which means you can switch a 4000 watt geyser for as little as R600+ installation (they clip directly into the DB so the installation cost is min.)

[Bransby]

hi guys and girls

I have heard that I cant run my UPS's off of my inverter. is this true? i have 2 servers running off 350w power supplies and both have UPS's and my inverter is a 1200w.

can anyone help?

[Dave A]

If your inverter isn't producing a pure sine wave, you'll probably have problems

I've had situations where the UPS wouldn't accept power from a generator, let alone an inverter

[Bransby]

how will I be able to check or should I call an electrician in?

[deon43]

Inverter/ups kwasi/ sine

Hey Guys and Girls, please post your enquiry on what you need and what application you want to drive e.g. the load or devices and for how long you want to sustain the power backup, Inverters are obvious the correct way to go as they are silent, noiseless, smokeless and on and on and very reliable. We are professional engineers on this applications and we do units from 600 watt up to 285 KW with online or offline technology. note the two differences, a inverter and a ups are quite different as UPS units, unless specified otherwise are shorterm backups and mostly “Kwasi� wave or as the public calls it Square wave (A step related formed sine wave, looks like staircase and bad for inductive equipment) and really very inefficient and bad for any system. We believe in making use only of Sine wave inverter equipment and with the high production volumes it does cost more or less the same these days as the Cheaper Square wave crap of earlier. Good advice, do it correct the first time and get a reliable supplier!! You can mail me on deon@electro-web.co.za and we will gladly help.

[Dave A]

how will I be able to check or should I call an electrician in?

An electrician might help, although not many have the sort of equipment needed to analyse the wave shape. You could test to see if the UPS will accept the power from the inverter. In fact, when setting up any backup power situation it's a good idea to proactively test it and not just wait for a crisis to occur.

Ultimately you probably need to be looking at your overall backup power strategy. Why do you need a UPS running off an inverter supply in the first place?

[deon43]

Inverters and Info

Checking if a inverter/UPS if not specified in the specification sheet can only really been done by means of a Oscilloscope, most electronic guys have such equipment, TV repair shops Radio repair shops and so on. Funny enough is that Sine wave inverter manufacturers are proud of their products and thus have no problem on adding Sine wave inverter on the description. If not mentioned directly on the Info pages or specification, be careful, that probably the real reason why not mentioning it and selling it cheap, lol Keep on buying until you learn to do the right thing and read the info! Most reliable inverters have a pre-power stage we call a Power Factor correcting circuit which serve a double purpose inside the inverter, firstly to make sure it can run at a good Power Factor of at least 0.9 that makes the system very efficient and secondly it compensate for input power fluxuations, thus it will easily work also from a generator. Good recommended quality worldwide systems are the Cotek systems (only inverters not Ups all sine wave) very expensive and the "POWERVERT" systems (UPS and inverters all sine wave) very good and relative cheap but only available from June onwards in SA.

[Daves]

Hi all, is this forum still active?

daves

[Dave A]

With Eskom saying it's going to take 5 years to get more generation capacity online and existing reserve generation capacity tight, I don't think the crisis is over

[murdock]

Checking if a inverter/UPS if not specified in the specification sheet can only really been done by means of a Oscilloscope, most electronic guys have such equipment, TV repair shops Radio repair shops and so on. Funny enough is that Sine wave inverter manufacturers are proud of their products and thus have no problem on adding Sine wave inverter on the description. If not mentioned directly on the Info pages or specification, be careful, that probably the real reason why not mentioning it and selling it cheap, lol Keep on buying until you learn to do the right thing and read the info! Most reliable inverters have a pre-power stage we call a Power Factor correcting circuit which serve a double purpose inside the inverter, firstly to make sure it can run at a good Power Factor of at least 0.9 that makes the system very efficient and secondly it compensate for input power fluxuations, thus it will easily work also from a generator. Good recommended quality worldwide systems are the Cotek systems (only inverters not Ups all sine wave) very expensive and the "POWERVERT" systems (UPS and inverters all sine wave) very good and relative cheap but only available from June onwards in SA.

if the person selling the equipment cant provide the equipment to test...best you find someone who can...how do they verify the equipment they are selling is correct and functioning correctly during commisioning.

Now is a good time to enquire about generators and invertors cause most of the fly by nights are out of bussiness or found other opitunities to make quick money.

[SeanM]

Evening All

I recently install a 5kva hybrid inverter upon doing my test I noticed that when the installation was being fed from the grid all my sockets tested as they should and the earth leakage tripped at 20 ma. When I changed over to the inverter my polarity tester indicated that the earth was now missing from the socket circuits.

I then proceeded to test on the input to the inverter:

L-N = 235 volts
N-E = 0 volts

On the output of the inverter:
L-N= 230 volts
N-E = 90 volts

I then switched the inverter off and had the grid power still feeding the inverter

Input:

L-N = 235 volts
N-E = 0 volts

Output:

L-N = 0 volts
N-E = 24 volts

It seems that the inverter is faulty.

[GCE]

Hi SeanM

It appears that your inverter output is not isolated from the input .

You need to earth the neutral on the output when it loses the grid and remove the earth under grid operation.In the higher quality units , the output is isolated from the input whether it is in grid or back up mode.

Make sure that the output is not earthed when on grid mode as you could become the star earth point for the transformer feeding the street under a fault condition , or if somebody steals the earth neutral link in the sub station.
It is why you have to install 4 pole change over switches on back up equipment and the reason for 6.1.6.

Basically only the supplier can earth the neutral - When you use municipal supply , they are obviously the supplier - when you are in back up mode , you are the supplier.

6.1.6 The neutral conductor shall not be connected direct to earth or to the
earth continuity conductor on the load side of the point of control except as
allowed in 7.16.4