1000W/2000W Pure Sine Wave 12v to 240v Power Inverter

SnowT · Guru

Inverter Musing..

oldtrack123 · Guru

HI Snow

A good post which I am sure many will find interesting

But recheck your [quote}" You can Plug as many Class items into the inverter as you Want" [end quote],you left out the 2 smile

Yes, some gear will require at least NEAR pure sine wave

Some will run on not so pure sine wave but may overheat OR simply malfunction

The correct terminolgy is:

[a]Square wave

modified SQUARE wave [sine waves do not need to be modified]

A modified Square wave can vary greatly in its wave form depending on how many steps there are in the wave form .

They can also lack any real smoothing,so have sharp rise rates in each step this can be detremental to some gear .

[c]A "pure" Sine wave inverter has many, many, steps with smoothing of those steps to reduce the flat sections

Rating

The next thing to consider is the inverter rating

It will have two ratings

[a]The continious rating is that load IT can handle indefinately, without overheating.

That cannot always be considered as a simple WATTS loading ,as the actual Amps loading is the heating factor

Inductive loads[ motors are a typical example, but Switch mode devices also have PF] will draw more current than the Watts rating of the motor/device would indicate due a condition called "power Factor"

Pf can vary from around 0.5<,1.0

At 0.5PF the actual current for a 100W device will be double the calculated current using the simple Watts/volts rule

[bThe short term overload or surge rating

This is the load that the inverter can handle for a specified time with out damage, with low thermal mass devices such as inverters it is usually only for a few second.

This is for such purpose as Motor Starting where the motor should be up to speed within a few seconds

[c] within those limits there are small degrees of overload that can be tolerated for SHORT periods, exceed those limit s& the inverter should trip out to protect itself

The load rating of a device /appliance includes it losses

If It is rated @100W that is the load it will put on the source[ inverter]

If the inverter is rated@ 100W Continious,It should be able to run that 100W load without over heating ,however ambient temp can come into the picture so it is best to have a margin of safety in the inverter rating for those situations.

Inverter Efficiency

Depending on quality Inverters have a load efficiency usually ranging from 80% to 90%

That simply means they have internal losses when under load of of 10 < 20% of that load

If the load is 100W they will draw 110 <120W from the source

If the voltage ,[under load of 100W] at the inverter terminals is 12.6V , they will draw is 8.73 A<9.52A

If the voltage at the inverter terminals is 11.6V, they will draw 9.48A<10.34A

PeterQ

-- Edited by oldtrack123 on Monday 14th of July 2014 12:00:51 PM

hako · Guru

Can something be added re 12V cable sizing from battery to inverter plus fuse size required to operate with please.
I bought a 2000/4000W unit which required starter motor thickness cables plus a 200amp fuse otherwise it overheated the cables.

SnowT · Guru

hako wrote:
Can something be added re 12V cable sizing from battery to inverter plus fuse size required to operate with please.
I bought a 2000/4000W unit which required starter motor thickness cables plus a 200amp fuse otherwise it overheated the cables.

I see if I can re-find the information that I used for my system..

Re - the Fuse Size.. All the Fuse is for is to Protect the Cable... At least that was what I was taught at trade school..

I see if I can find the information..

And yes Peter I'm Glad you added to the Topic..

Juergen

Mike C · Senior Member

Confused... mine is a Victron 3000 VA inverter Charger so how many watts is that?

cheers

Mike

hako · Guru

SnowT wrote:
SNIP
Re - the Fuse Size.. All the Fuse is for is to Protect the Cable... At least that was what I was taught at trade school..

I see if I can find the information..
And yes Peter I'm Glad you added to the Topic..

Juergen

Thanks Juergen - I thought it was to protect the appliance?....anyway, I found that when I used thinner cable and a 100amp fuse, both cable and fuse were hot so I doubled the sizes of both and then they stayed cool till the inverter died. This was with a 2000W PSW inverter.
Regards

03_troopy · Guru

The fuses are to protect both the cable and the appliance. Usually a fuse at the power source is to protect the cable, and a fuse of smaller size than the cable current carrying ability, close to the appliance, to protect the appliance. The rating of the fuse, close to the appliance, will normally be specified by the manufacturer of the equipment in their installation documentation. The fuse at the power source, used to protect the cable in the event of a short circuit downstream of the power source, is determined by the safe current carrying capacity of the cable (de-rated depending on whether it is in conduit, wire bundle etc.).

hako · Guru

Thanks 03 troopy and Juergen - I was totally unaware of that - I've always followed the principle of having the fuse as close to the power source as possible and have never figured to protect the cable.
Regards

Countrytech · Veteran Member

A question on where is the best place to mount the inverter. Ideally close to the battery is advised, but there are suggestions that it is not advisable with regard to battery emissions, in a confined space. How to determine a 'closed space'. Is the front boot of a van, with 2 sealed lead acid batteries, a suitable place? Is an enclosure within the van, containing a SLA battery, but having some air circulation ok? Is under the bed, with inverter and batteries a safe place? I have seen all these situations, but would like to know which is the recommended mounting place.

Thanks

John

oldtrack123 · Guru

Mike C wrote:
Confused... mine is a Victron 3000 VA inverter Charger so how many watts is that?

cheers

Mike

HI Mike

Unfortunately there are two ways of rating Inverters & generators that nan be in watts /kWatts or Va/kVA

To Find the watts rating the specs should indicate at what Power factor PF the kVA rating applies

It is usually around 0.6PF ,that would give a WATTS rating of 1800Watts

kVA 3000 x by PF 0.60 = 1800W

PeterQ

Mike C · Senior Member

Thanks Peter
Appreciate the explanation..

Mike

oldtrack123 · Guru

Countrytech wrote:
A question on where is the best place to mount the inverter. Ideally close to the battery is advised, but there are suggestions that it is not advisable with regard to battery emissions, in a confined space. How to determine a 'closed space'. Is the front boot of a van, with 2 sealed lead acid batteries, a suitable place? Is an enclosure within the van, containing a SLA battery, but having some air circulation ok? Is under the bed, with inverter and batteries a safe place? I have seen all these situations, but would like to know which is the recommended mounting place.

Thanks

John

Hi John

Any electronics do not like Acid fumes

Flooded wet cell batterries near an inverter is a definate NO NO .

So called seal batterries do still have vents to release gas pressure, if required.

The other slight risk is an explosion due to hydrogen gas emmisions from the battery.

Best that the inverter be well shielded from the battery comprment. so no possabity of fumes/gases getting to the inverter

The requirement to be as closes as PRACTICAL to the battery is due the voltage loss in the 12V connecting cables

That loss can be compensated for with HEAVIER cables , the actual conductor size will depend on distance [cable length] & MAX current to be drawn .If

PeterQ

oldtrack123 · Guru

hako wrote:
Can something be added re 12V cable sizing from battery to inverter plus fuse size required to operate with please.
I bought a 2000/4000W unit which required starter motor thickness cables plus a 200amp fuse otherwise it overheated the cables.

HI Hako
The Actual cable size [Coppper cross sectional area] depends on length of cable & MAX current the cable will be requires to carry
Cables that are too small for the current can l give two problems:
[1]They may overheat
[2]THe voltage lost in the cables will do two things ;
[a]The inverter attempts to draw even more current to supply it's load with a degrre of snow balling .
The more it draws to more the voltage drops until something happens
Either the Supply fuse blows or the inverter shuts down on UNDER voltage to protect itself from burn out
The voltage X by current is energy lost in the form of wasteful cable heating.

The supply fuse should be at the source to protect the cables
It's rating should be NO MORE than the cables continiuos rating, corrected for ambient temp, or lack of free air cooling.
It can have a lower rating to match that of the inverter ,as ADDITIONAL protection, but they do have their own internal fuse protection
That only applies if the inverter is the only load on THAT circuit.

That 4000W inverter could draw a peak current of 380/400A[If due to voltage drop in the cables the actual voltage at it's input wasdown to10.6>10V
PeterQ
I

-- Edited by oldtrack123 on Monday 14th of July 2014 09:01:00 PM

Countrytech · Veteran Member

Thanks for that PeterQ, I'll leave them where I installed them. Just wanted to check, as I get many opinions that what I have done is not necessary. My cables are suitable, and a breaker is installed.

John

Mike C · Senior Member

Just found the spec sheet for the Victron Quattro Unit I have

Cont output power @25c (VA) 3000
Cont output power @25c (W) 2500
Cont output power @40c (W) 2200
Peak Power (W) 6000

So assume the PF must be around 0.833

Why don't they simply stick with one unit of measure... or is it that 3KVA sounds more powerful than 2500 Watts?

Cheers

A slightly more educated (but still confused) Mike

-- Edited by Mike C on Monday 14th of July 2014 09:07:04 PM

oldtrack123 · Guru

Mike C wrote:
Just found the spec sheet for the Victron Quattro Unit I have

Cont output power @25c (VA) 3000
Cont output power @25c (W) 2500
Cont output power @40c (W) 2200
Peak Power (W) 6000

So assume the PF must be around 0.833

Why don't they simply stick with one unit of measure... or is it that 3KVA sounds more powerful than 2500 Watts?

Cheers

A slightly more educated (but still confused) Mike

-- Edited by Mike C on Monday 14th of July 2014 09:07:04 PM

Hi Mike

I thnik some do fall for the kVA rating being bigger & better

In the past All Ac power generating sources were rated in kVA.Even power houses were quoted as xxxx mKVA, Now virtualy all use mW

But it has been the general practise for quite a while to use the more understandable Watts method

PeterQ

Mike C · Senior Member

I could make a fortune by putting 2KVA stickers on 200W inverters just have to add PF 0.1 in the small print :)

oldtrack123 · Guru

Mike C wrote:
I could make a fortune by putting 2KVA stickers on 200W inverters just have to add PF 0.1 in the small print :)

smile biggrin

PeterQ

Friar Park · Senior Member

Thanks to all of you Fellas for educating a genuine electrical/electronic dummie especially SnowT for getting it started

Thanks

Friar

Phil C · Guru

Hi Guys

Thanks for that. These bloody inverters have been a thorn in my side for ages. The prospect of cables CSA has raised its ugly head, when I was installing in industrial and domestic installs, we used maximum demand as in AS3000 as the guide to cable cross section. It was related to length of cable run, maximum expected current, etc.

As far as DC is concerned thats a new can of worms, we have a 2500W (not VA, it says) inverter two 12mm sq cables on both pos and neg terminals, cable length is about 400mm, expectation from me is not too much volt drop at max current.

This is the big deal for DC applications as the higher the wattage device the more current it draws thus heating the cable and causing more ohm's law volt drop (not nice) V = IxR. Imagine 200 watts on 12 volts a lot of amps.

Anyway, thanks to all for the enlightenment. biggrin

Safe travels

hako · Guru

Thanks Peter for the info.
Regards

oldtrack123 · Guru

Mike C wrote:
I could make a fortune by putting 2KVA stickers on 200W inverters just have to add PF 0.1 in the small print :)

Hi Mike

[1] The cause of overheating in any electrical device is excess current [Amps x Ohms{Watts} heat generated in the components

[2]A little futher SIMPLE wink explanation

[a]AxAxR=Watts

AxV=Watts

[c]AxVx PF =Watts

[3]AS you can see in each of the above Amp is a factor

Now PF is the result of the current lagging the voltage due to inductance

That simply means that a PF of 1.0 the current a voltage peak together on each half cycle[10A at 240V =2400W]

All the curren tis being supplied at full voltage

But with a PF of say 0.5, the Current peak is delayed until after the voltage peaks [ by 50% in each cycle] 10A At 120V=1200W

With a PF of 0.1 = 10A x24V =240W

Taking the last case you can see that the power is actual =1A x nominal 240v =240W

That apparent extra 9A that would be flowing is referred to as WATTLESS current, since it does not have a voltage component, it has no energy

But look again at [1][a]that Current still has to obey that law , the souce winding have resistance lets say that is 2 Ohm thn Ax AxR =10x10 x2 =200W

Tthe losses as heat in the SOURCE windings is the same no matter watt the PF of the load.

Be aware it is the inductive load that has the PF generating effect

How is that for confusion

PeterQ

-- Edited by oldtrack123 on Thursday 17th of July 2014 01:03:25 PM

hako · Guru

Here's something to ponder: what happens when when you have loose or corroded terminals....how will that effect the fuse and cable. I know from experience both will get very hot despite not being overloaded. How can one ensure the connecvtion matches the cable/fuse?
Regards

SnowT · Guru

Denis, one of the major thing's that should be done on a regular basis is to check all the connects.. As you have pointed out you might have issues of poor connections..

A Poor/faulty connection can burn out Real easy....

fix the issue no matter what it is.. Corroded terminals Clean them up.. reattach them and make sure you smear a bit of Terminal jell on them.. [Simplified fix]

So it is worth the time to check them for faulty connection's..

Juergen

oldtrack123 · Guru

hako wrote:
Here's something to ponder: what happens when when you have loose or corroded terminals....how will that effect the fuse and cable. I know from experience both will get very hot despite not being overloaded. How can one ensure the connecvtion matches the cable/fuse?
Regards

Hi

What actual happens will depend on the resistance in that connection

If 10A is flowing & the connection has 0.5 Ohms resistance ,then the heat generated in that very localised area would 50W

This would apply even if the cable rating was far in excess of 10A the cable size only effect is possible conduction of some of the heat away from the actual faulty connection & THAT usually means damaged insulation, even further encreasing the risks [possibly of short circuits]

50 Watts of very localised heat can get very hot, just consder a 50W soldering iron or even a 50W light bulb[although a lot of that 50W isused generating light]

Fuses' circuit breakers cannot detect localised heating , that heat ,to them is just the same as the load [solderig iron]

The localised heat will oxidize the connection ,encreasing the resistance, which will / may reduce the current a little, but actually the effect will snowball ,getting hotter & hotte ,rPossibly resulting in a major fire

.There realy is no protection against overheating connections causing fire, except assembling/ maintaing ALL connection with a Clean contact to contact face & TIGHT.

THe best way to mimimise the problems are:

[1] use connections that are rated no less than the cable rating

[2]Ensure cables & all connection contact faces are clean bright metal

[3]Ensure they are fully tightened ,

oops I see Snow just beat me biggrin

PeterQ

-- Edited by oldtrack123 on Thursday 17th of July 2014 11:30:02 PM

Bravehearts · Veteran Member

Hi to all, please forgive me as I am still a little confused. My van is 18months old and I have two 80W Solar panels, two brand new 120amp hour heavy duty batteries (I replaced the single marine type battery supplied with the van) and a 600W pure sine wave inverter connected to the batteries via fused (50amp) cables. The inverter and panels were supplied by Jaycar and fitted by a recognised Solar Company in Gin Gin, Qld. I also have a 2KVA Honda generator. My issue is when we are in a area where we are not allowed to run the generator (e.g Seaforth Council Parl near Mackay) and I want to run the washing machine (which is a top loader small capacity fitted in the ensuite) what is the correct method of operation. I have been told the inverter could be hard wired into the 240v power system via a registered sparky, or altenativley I could have a cable made up to plug into the inverter and then a plug fitted to the other end to plug into the van which would then make the entire system 240v. However I believe such a cable is not legal, although I have seen them used. Another suggestion was to purchase an Amphibian Cable which is legal and simple plug that into the inverter and then into the van power inlet point. I have contacted four companies who advertise themselves as RV/Caravan Solar specialists and I am still in the dark as I cannot get a definitive answer from anyone. I would greatly appreaciate any advice on this.

hako · Guru

Thanks Snow and Peter.

Jaahn · Guru

Hi smile

Informative posts all.

However there is one thing that has not been said about inverters. Safety !! They put out 240volts just like the mains and can kill you just like the mains power. HOWEVER the mains have an earth connection and possibly an earth leakage shut off to protect you in case of a fault in the appliances or the like. A stand alone inverter (or a generator too), do not have these protections. If you get an appliance fault then it could be live and no fault would be noticeable!! Being inside a metal frame or metal case would mean that you could get a circuit if you touch it. confuse Care is always good but more so with these situations. Water spilt or rain is to be avoided also.

Take care Jaahn

-- Edited by Jaahn on Friday 18th of July 2014 09:34:55 AM

oldtrack123 · Guru

Bravehearts wrote:
Hi to all, please forgive me as I am still a little confused. My van is 18months old and I have two 80W Solar panels, two brand new 120amp hour heavy duty batteries (I replaced the single marine type battery supplied with the van) and a 600W pure sine wave inverter connected to the batteries via fused (50amp) cables. The inverter and panels were supplied by Jaycar and fitted by a recognised Solar Company in Gin Gin, Qld. I also have a 2KVA Honda generator. My issue is when we are in a area where we are not allowed to run the generator (e.g Seaforth Council Parl near Mackay) and
[1]I want to run the washing machine (which is a top loader small capacity fitted in the ensuite)
[2] what is the correct method of operation. I have been told the inverter could be hard wired into the 240v power system via a registered sparky,
[3]or altenativley I could have a cable made up to plug into the inverter and then a plug fitted to the other end to plug into the van which would then make the entire system 240v.
However I believe such a cable is not legal, although I have seen them used.
[4] Another suggestion was to purchase an Amphibian Cable which is legal and simple plug that into the inverter and then into the van power inlet point
[5] I have contacted four companies who advertise themselves as RV/Caravan Solar specialists and I am still in the dark as I cannot get a definitive answer from anyone. I would greatly appreaciate any advice on this.

Hi

[1]It will be case of trying the washing machine on that inverter & see if it will handle it OK

It may be best to alaways start it with no load in the machine whenever possible Doing that will reduce the START up load on the inverter

[2]Yes, it can be hardwired in by a registered sparky, who understands the requirements of the Standard AS 3001[Many have no experience with THAT standard]

It will envolve change over switching to ensure the RCD/Safety switch is fully functional

[3] Anyone who makes up such a lead should be shot, such leads are potentially DEADLY & are forbidden!

!Do not even THINK of such an arrangement

[4]THat would have little advantage as the RCD/ safety switch will still not be operational

[5]Not surprised

Now the best /safest way apart from [2] Is to simply plug the washing machine drectly into the Inverter[you may use a short extension lead if necessary]

One safety recommendation should always be considered when using"Portable inverters "[not permanently wired in as in {@] above

IS :

Do not connect more than ONE class 1 appliance [have a 3pin plug] at any time

BUTyou may connect more than one if they only have a 2pin plug

Hope that helps

PeterQ

it

oldtrack123 · Guru

Jaahn wrote:
Hi
Informative posts all.
However there is one thing that has not been said about inverters. Safety !! They put out 240volts just like the mains and can kill you just like the mains power. HOWEVER the mains have an earth connection and possibly an earth leakage shut off to protect you in case of a fault in the appliances or the like. A stand alone inverter (or a generator too), do not have these protections. If you get an appliance fault then it could be live and no fault would be noticeable!! Being inside a metal frame or metal case would mean that you could get a circuit if you touch it. Care is always good but more so with these situations. Water spilt or rain is to be avoided also.
Take care Jaahn

-- Edited by Jaahn on Friday 18th of July 2014 09:34:55 AM

Hi Jaahn

YES , a timely warning & it does not just apply to inverters

IT also applies to portable generators

See my last post smile

PeterQ

Peter