Cable Size

[ivor dispatch]

sidewinder last week the DTI guide was the be all and end all of the posts,,,by you and others, this week is does not matter ??????

:|

so long as it ticks the boxes in 2,1,4 I & 2,1,4,2 reckon its ok pal

 

[Sidewinder]

You don't seem to have a good grasp of this do you.

Once again you have not answered my question.

Why does this seem like deja vue.

I feel that this thread is going the same way as the last so perhaps I had better bow out now because it seems that some people are not prepared to ...

I dare not type any more.

It just beggars belief.

 

[ivor dispatch]

You don't seem to have a good grasp of this do you.Once again you have not answered my question.

Why does this seem like deja vue.

I feel that this thread is going the same way as the last so perhaps I had better bow out now because it seems that some people are not prepared to ...

I dare not type any more.

It just beggars belief.

I do not know what your question is,, I do not know why you are not sticking with newmans install?? as I reckon I would have a 550v max open circuit at -10 for a 4000TL,, so I would source a cable for that rating?

 

[newman]

That's a good result.BUT

He only has half the story.

He has found with his voltage recording that the voltage at the inverter is going too high.

But I still believe before he does anything he also needs to run that test with the voltage recorder at the supply intake, so see the range of variation there as well. i.e get the FULL picture from the test the DNO did and rather brushed under the carped.

Only then will he know how much headroom he has got, i.e how much voltage rise can be tollerated over and above the maximum voltage seen at the intake.

Until he does that, he can't do any sensible calculations. so anything he does now is a bit of a stab in the dark. Try a thicker cable and see?

so the ducting seems a good idea.

In my have inavertanly mis led....

The volt recording was a failure as when the sun was shinning around mid day the inverter would only operate for about 3-5 seconds then cut out ,it did this a few times,only running for a few seconds then cutting out,after a few times a red light came on ,the inverter cut out for about 10 mins then reconnected ,when it cut out again I gave up on the volt recorder and switched to half PV power

Today was dull so been on full power but has not cut out

The ider of the recorder was to plot the volt rise and compare it to the inverter log to see at what voltage and what cause the inverter was cutting out ,because the time scale is so small this can not happen now

 

[ivor dispatch]

In my have inavertanly mis led....The volt recording was a failure as when the sun was shinning around mid day the inverter would only operate for about 3-5 seconds then cut out ,it did this a few times,only running for a few seconds then cutting out,after a few times a red light came on ,the inverter cut out for about 10 mins then reconnected ,when it cut out again I gave up on the volt recorder and switched to half PV power

Today was dull so been on full power but has not cut out

The ider of the recorder was to plot the volt rise and compare it to the inverter log to see at what voltage and what cause the inverter was cutting out ,because the time scale is so small this can not happen now

I think you said you had a SMA 4000TL, tomorrow or even now(if still on) have a look on the display next to the grid/pylon and it will give a voltage . if possible please post the voltage and the w output

Thanks

 

[Sidewinder]

My question is:

There are other considerations do you know what these are?

Until you answer this I see no point in my posting any more.

Oh, and I expect you to tell me what these are, I know, but, I am not going to tell you because i don't believe that you know.

What you do know however is that I will not tell you, I will merely guide you to the answer by asking you questions.

This is the way I am, if you don't like it then tough.

I don't need, or want, to justify myself to you as I have no idea who you are or what you know, or your qualifications or competence.

 

[ivor dispatch]

My question is:Until you answer this I see no point in my posting any more.

Oh, and I expect you to tell me what these are, I know, but, I am not going to tell you because i don't believe that you know.

What you do know however is that I will not tell you, I will merely guide you to the answer by asking you questions.

This is the way I am, if you don't like it then tough.

I don't need, or want, to justify myself to you as I have no idea who you are or what you know, or your qualifications or competence.

I am sorry you feel so important

Thanks

:consoling

 

[newman]

I think you said you had a SMA 4000TL, tomorrow or even now(if still on) have a look on the display next to the grid/pylon and it will give a voltage . if possible please post the voltage and the w output Thanks

According to my installer the voltage readings are only a rough guide ,not precise enough to be accurate, this is wyh he invested in a voltage logger, but for whats it worth I did see 262Volts on the display

 

[Sidewinder]

I am sorry you feel so important Thanks

:consoling

I don't feel important at all in fact, so once again you are wrong.

I just don't see why I should justify myself to someone who does not have the decency to answer the questions asked of him.

You have no idea of who I am, I have no idea of who you are.

All I see is me answering the questions you post, and you ignoring my questions and posting some information that is wrong or simply your opinion without back up references.

---------- Post Auto-Merged at 20:17 ---------- Previous post was made at 20:15 ----------

... the w output...

Which is what exactly?

 

[ivor dispatch]

According to my installer the voltage readings are only a rough guide ,not precise enough to be accurate, this is wyh he invested in a voltage logger, but for whats it worth I did see 262Volts on the display

If you can get to the inverter when it is at low output/low sunlight this will give an idea of the voltage at the inverter and a rough idea of the incoming voltage. At high sunlevels the inverter will be working hard so voltage will rise.

262V is very high!

 

[newman]

Prodave, the DNO have hit the dizzy hieghts of 253v at the intake,using the sma guide to grid connection will give the installer a visual represention to show the relationship between voltage/grid&circuit impedance. It may be very expensive to try and match a cable for the AC so moving the inverter to the mains intake and sizing a cable for DC could be a cheaper option

To be honest Ivor this idea is a non starter as if I suggest it to my installer it would be my idea and if it didn't work ,and I have my douts,it would be my fault ,I would much rather stick to manufactures instulation guides and get the right size of cable thank you

 

[Sidewinder]

According to my installer the voltage readings are only a rough guide ,not precise enough to be accurate, this is wyh he invested in a voltage logger, but for whats it worth I did see 262Volts on the display

On what grounds does he say that these readings are not precise enough?

These will be the readings that the inverter software uses to control itself, thus, if these are outside the programmed limits, then regardless of what is going on outside the inverter it will still shut down.

 

[ivor dispatch]

The panels are 2 strings of 8 (newman said 4 x 4mm cables going to SMA4000 TL Inverter) - Suntech 250'sIf you had read the old thread that was locked you would know that :slap

Voc @25degC 37.4V

Temp Coefficient of Voc -0.34%/degC

At least thats what the data sheet says i have

I do think you and others should calm down a bit.

I was asking for the AC voltage hence the picture of the pylon but I am sure you knew that.

:|

 

[newman]

If you can get to the inverter when it is at low output/low sunlight this will give an idea of the voltage at the inverter and a rough idea of the incoming voltage. At high sunlevels the inverter will be working hard so voltage will rise.262V is very high!

262v was at midday and bright sun then it triped out

 

[newman]

On what grounds does he say that these readings are not precise enough?These will be the readings that the inverter software uses to control itself, thus, if these are outside the programmed limits, then regardless of what is going on outside the inverter it will still shut down.

He did mention talking to SMA,but to be honest if you watch the screen it alternates between Volts and Amps so you never get a reading when the inverter trips I think thats why the installer invested in a dataer logger

---------- Post Auto-Merged at 20:36 ---------- Previous post was made at 20:34 ----------

See the display Pic i posted, was the 262 on the LH or RH side ? as it displays both ac and dc voltages, then the dc voltage cycles to current from memory---------- Post Auto-Merged at 20:32 ---------- Previous post was made at 20:28 ----------

I am calm, well chilled with a nice pint of water

I was merely posting the dc strings and panels in relationship to your post here

Or were you talking about the 550V on the AC side there ?

You had specified a temp correction which normally relates to the DC side of calculations on the string, but i may be wrong

I get confused easily according to my missus as i am merely a man.....

IT was on the right

 

[Sidewinder]

He did mention talking to SMA,but to be honest if you watch the screen it alternates between Volts and Amps so you never get a reading when the inverter trips I think thats why the installer invested in a dataer logger---------- Post Auto-Merged at 20:36 ---------- Previous post was made at 20:34 ----------

IT was on the right

As I understand it this inverter can send the data "it" sees to an external data logger by Bluetooth, that would be a better bet as anything external does not "see" what the inverter "sees".

Calibrated 1ph power analysers are not that unusual TBH, I carry one in the van at all times, along with a calibrated a.c./d.c. clamp meter.

A data log from the inverter data & the DNO data would be the best thing to check against, it is possible that there is a fault in the A-D converter in the inverter,V or I circuit.

I would expect the display to toggle between V & I as you are exporting power which is VI/VA.

 

[ivor dispatch]

To be honest Ivor this idea is a non starter as if I suggest it to my installer it would be my idea and if it didn't work ,and I have my douts,it would be my fault ,I would much rather stick to manufactures instulation guides and get the right size of cable thank you

I agree Newman, as you say if you give an instruction to the installer its your call . I am just trying to point out there are other options but as I did not cross my t's and dot my i's the usual ones are on my case. But it would not be outside of manufactures guidlines or IEE or DTI guide lines to have a long DC run.

I think you must have quite a high incoming voltage to cause these problems(I am not saying the installer is correct not to use the 1%VD but this is there to protect the voltage range in this country and it can not when you get to 250v and above)

I think the 1% VD is misleading to many installers as is obvious by the comments from some on your locked thread, it should be shown or explained correctly at class room level taking into account all the variables voltage&circuit impedance&grid impedance so a clear reason for the importance of the cable size is ingrained in the head of the designer.

---------- Post Auto-Merged at 20:59 ---------- Previous post was made at 20:46 ----------

262v was at midday and bright sun then it triped out

The inverter will trip at 264v sunny explorer is not quick enough to pick it up . For fear of repeating myself down load the sma guide to grid connection( I have posted it before ) this is very close to what you can expect for trip levels on your system you need the incoming voltage with the inverter switched off and the grid/circuit impedance L&N as close to the inverter terminals as poss,(no EARTH readings) and use the graph to work it out.

 

[newman]

The RH side is most definitely ACAt 262 Volts i would seriously ask the DNO for a copy of their data log, if they wont give you this then ask for a letter confirming all the voltages and spikes they recorded and a copy of their data loggers calibration certificate

I have asked the DNO for a copy of their data log but they say give me one but they did give me some figures

Min 227.9v

Ave 240.7

Max 247.8

when asked about the 253v in the email they rechecked and said there where a couple of spikes in the middle of the night at 255v. All these readings were done when the PV was switched off

I thought the voltage on the right hand side of the display was the voltage reading at the inverter and because I have a thin wire this is why it is high

 

[ivor dispatch]

See the display Pic i posted, was the 262 on the LH or RH side ? as it displays both ac and dc voltages, then the dc voltage cycles to current from memory---------- Post Auto-Merged at 20:32 ---------- Previous post was made at 20:28 ----------

I am calm, well chilled with a nice pint of water

I was merely posting the dc strings and panels in relationship to your post here

Or were you talking about the 550V on the AC side there ?

You had specified a temp correction which normally relates to the DC side of calculations on the string, but i may be wrong

I get confused easily according to my missus as i am merely a man.....

:|

 

[steptoe]

I think the DNO are being a bit avoidal,

if they refuse to give you a datalog tell them you require it to be done again and a datalog provided as you are having an independent log done and if they are misleading you you will bill them accordingly.

if they are pushing their voltage limits then the inverter is really going to struggle with the small cable trying to push the power back down it.

---------- Post Auto-Merged at 22:12 ---------- Previous post was made at 22:10 ----------

ivor, even though the DTI guide may say to use a longer DC cable, the cable must have the approval of the manuf to be used for the potential DC that may flow through it, it must also be MCS approved, I dont think many manuf of SWA have had their cable type approved by MCS.