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Sunsynk - CT Clamp


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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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