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Sunsynk - CT Clamp


Bloubul7
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Hi All,

Need some advise regarding the CT coil on a Sunsynk 8.8kw unit.  I have installed the CT Clamp that came with the unit but got a zero reading on the screen, thinking that the CT clamp might be faulty I bought a new 100A clamp to test but I'm still getting a zero reading.  The CT clamp positive is connected to pin 3 and the negative to pin 4.  Am I missing something?

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52 minutes ago, Bloubul7 said:

Hi All,

Need some advise regarding the CT coil on a Sunsynk 8.8kw unit.  I have installed the CT Clamp that came with the unit but got a zero reading on the screen, thinking that the CT clamp might be faulty I bought a new 100A clamp to test but I'm still getting a zero reading.  The CT clamp positive is connected to pin 3 and the negative to pin 4.  Am I missing something?

I have the 8kw sunsynk and had the same issue. 

I connected the positive to 3 and negative to 5 and it worked for me. 

Edited by Achmat
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6 minutes ago, JustinSchoeman said:

It is for measuring grid current (for measuring and controlling grid export).  That way you can supply/supplement house loads on the grid side of the inverter without exporting to the grid.

I guess I don't get why it is external.  Current Transformers are installed on all inverters (and UPS for that matter) but they typically housed internal to the device.  Since the device can't control anything else that would export, I'm curious how having it external is beneficial?

EDIT: Ok I think I get it.  All the current you consume may not actually be going through the inverter input.  You may have significant loads in parallel to the inverter and having this external CT allows you to monitor and back feed for those situations without actually needing to pass significant currents via the inverter.  Quite a cool feature if indeed that is what it allows.

Edited by Gnome
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5 minutes ago, Gnome said:

I guess I don't get why it is external.  Current Transformers are installed on all inverters (and UPS for that matter) but they typically housed internal to the device.  Since the device can't control anything else that would export, I'm curious how having it external is beneficial?

The grid connection on the inverter is bidirectional. The only way it can supply loads before the inverter is with an external CT clamp connected before all loads on the grid feed. 

Grid - >CT sensor - >loads - >inverter - >essential loads 

Without the CT the inverter will not know what the load demands are before the inverter in order to feed excess pv to these loads. 

Edited by Achmat
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1 minute ago, Achmat said:

The grid connection on the inverter is bidirectional. The only way it can supply loads before the inverter is with an external CT clamp connected before all loads on the grid feed. 

Grid - >CT sensor - >loads - >inverter - >essential loads 

Without the CT the inverter will not know what the load demands are in order to feed excess pv to these loads. 

I updated my post and figured as much :)

I assume you mean more something like this:

Grid - >CT sensor - >loads

Grid - >CT sensor - >inverter - >essential loads

So loads and inverter are in parallel but both monitored by the CT.

Edited by Gnome
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14 minutes ago, Achmat said:

It is a cool feature 

Basically you can leave your high draw appliances before the grid so in the event of load shedding only your essential loads will run from batteries. 

Yeah it is very cool.  It actually makes a LOT more sense than for example the Victron or Axpert approach where they try to allow overload with some silly electronics.  You just get a lot more reliable system by not having it go through the inverter when you clearly don't want it supplied that way.

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  • 3 weeks later...
On 2020/09/28 at 5:08 PM, Harry Khiani said:

The ct coils use 3456 ports . And please bear in mind that the arrows on the CT sensors should face the grid

I use a split phase so I guess that's why I need to use 4 ports

 

 

IMG_20200925_160147.jpg

 

On 2020/09/28 at 5:08 PM, Harry Khiani said:

The ct coils use 3456 ports . And please bear in mind that the arrows on the CT sensors should face the grid

I use a split phase so I guess that's why I need to use 4 ports

 

 

IMG_20200925_160147.jpg

Can you please explain why the arrows should face the grid and not the loads? In my understanding on building panels, the ct shows the direction of current flow. And by my thinking, it should measure all incomimg current and stop reverse flow? Im installing my 3rd sunsynk now and its the dirst time i meed to use the ct.

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2 hours ago, Martinvbiljon said:

Can you please explain why the arrows should face the grid and not the loads? In my understanding on building panels, the ct shows the direction of current flow. And by my thinking, it should measure all incomimg current and stop reverse flow? Im installing my 3rd sunsynk now and its the dirst time i meed to use the ct.

Polarity of the CT just affects the sign of the measurement, so it could theoretically have been either way around.  SunSynk uses the convention that positive is current flow out of the inverter for loads, so you need to point the arrow towards the grid to work with this convention.

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  • 2 months later...
On 2020/10/20 at 7:01 AM, Martinvbiljon said:

 

Can you please explain why the arrows should face the grid and not the loads? In my understanding on building panels, the ct shows the direction of current flow. And by my thinking, it should measure all incomimg current and stop reverse flow? Im installing my 3rd sunsynk now and its the dirst time i meed to use the ct.

Are you saying that one may not need the CT? I don't do export to grid, not applicable in my country, so does it mean that I really don't need to install the CT?

Edited by ojeysky
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On 2020/09/28 at 6:02 PM, Bloubul7 said:

Connecting the CT to pins 5 & 6 works.

The manual that came with the inverter was not clear to which pins to connect it to.  I followed the markings on the board and assumed it should be CT-L1

 

2104462740_SunSynk-CT(2).thumb.jpg.c8d66e5af8fc9a1fa42645d8b786406f.jpg

 

Mine is also at 3,4 I will also change to 5,6 but can you confirm if you had to shutdown inverter before doing this? Or can it be done while the inverter is supplying power

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1 hour ago, ojeysky said:

Mine is also at 3,4 I will also change to 5,6 but can you confirm if you had to shutdown inverter before doing this? Or can it be done while the inverter is supplying power

CT coil wires can be changed without sitting down the inverter. 

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1 hour ago, ojeysky said:

Are you saying that one may not need the CT? I don't do export to grid, not applicable in my country, so does it mean that I really don't need to install the CT?

It would depend on how the inverter is setup. 

If you have a grid present and loads before the inverter then you will need the CT coil of you want to send excess solar to these loads. 

If you have all loads on the inverter then you don't need the CT. 

 

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2 hours ago, Achmat said:

It would depend on how the inverter is setup. 

If you have a grid present and loads before the inverter then you will need the CT coil of you want to send excess solar to these loads. 

If you have all loads on the inverter then you don't need the CT. 

 


does the non critical stuff runs on solar during the day? If it is that would mean your CT coil is between you grid (main incomer) and your non critical stuff. So my CT coil is between my inverter and non critical stuff so if there is reserved power from the solar system it just goes to mid air if batteries are full and critical stuff are not using that much, thats my understanding. I wanted my CT coil between my non critical and Grid (main incomer). As my understanding is then reserved power from the solar system gets used by the non critical stuff. If you don't allow it to feed back onto the grid your reserved power stays your side of the CT coil. If your main incomer has no power the CT coil picks it up and stops the inverter  from feeding the non critical stuff. Hope it makes sense and if someone can give me an answer on if it does work like that. guy who installed my system says you dont install it like that, they way mine is installed with the CT Coil right after the Inverter and if you selected not to feed back onto the grid you wont need a CT Coil.  

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13 hours ago, Vassen said:

Sorry your response is a bit confusing. 
 

The ct coil needs to be installed on the main incoming line before the non essential loads. If the grid goes down, then nothing is fed back into the non essential loads. It’s only the load side of the inverter, also known as the essential loads that gets power. 
 

in my opinion, when the grid is present, whether you are powering the essential or non essential loads from solar, makes no difference.  The excess is still either coming from grid or battery. 
 

You can prioritize whether you want to use the solar to charge batteries or power the loads. If battery is prioritized, any excess will then go to loads. When batteries are fully charged your solar production will drop to match your loads. It can’t just produce and go into the air. 
 

most of the people choose to prioritize loads as this results in the biggest savings and generally the batteries are still full by the end of the day. This obviously depends on how big your pv array is. 
 

when loadshedding is near, you just disable the timer feature which means the battery does not discharge unnecessarily and is kept for loadshedding. Again, depends on how big the battery bank is 

thanks for your reply. I understand everything you have explained, doesn't really tell me what I want to know.

I hope this diagram explains it a little better what I'm trying to find out. 

The CT Coil is between the Main incomer and non Essential load DB.

does the solar feed back to the Non Essential Load DB?

i made a little block to show where mine is installed "CT coil Here"

i want to know what's the difference its going to make if i install it as of the installation manual and where mine is. 

 

image.thumb.png.2146d12bd2a75963d55ef368395d0814.png

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11 minutes ago, Wade said:

thanks for your reply. I understand everything you have explained, doesn't really tell me what I want to know.

I hope this diagram explains it a little better what I'm trying to find out. 

The CT Coil is between the Main incomer and non Essential load DB.

does the solar feed back to the Non Essential Load DB?

i made a little block to show where mine is installed "CT coil Here"

i want to know what's the difference its going to make if i install it as of the installation manual and where mine is. 

 

image.thumb.png.2146d12bd2a75963d55ef368395d0814.png

The answer to your question (highlighted in the quote) is yes, it does feed excess solar to power non-essential loads.

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