Hi All,

I know this has been discussed to death already and I used the search function, but there is no definitive answer. I figured lets get a thread going to answer the questions and have the info in the same place.

Question 1.

What amp rating of contactor should be used to create the earth/neutral bond? Does it need to be a high current 60A 230v or will a 6A 230V work fine? Does it even need to be a contactor or will a relay suffice?

Question 2. 

What size wiring should be used for the relay/contactor above? 

Question 3.

Which configuration of relay/contactor is best Normally Open or Normally Closed? Depending on which one you get will determine how it is connected and could have an effect on the answer to Question 2.

This is just my opinion and could be entirely wrong, so happy to be corrected.

Question 1 - I dont think it even needs to be a contactor honestly as it shouldnt be holding a high load and a relay should suffice. A contactor is probably a better idea thought for longer service life. When the bond is in effect any leakage from the circuit should trip the earth long before it gets to any decent amount of current.

Question 2 - Standard 2.5mm/2 should be fine as there is no major load. Thinner diameter should also be possible if using the L/N from the terminal block instead of the grid L/N

Question 3 - I have seen both used with the NO being used in conjunction with the L/N connectors to the left of the terminal blocks. I personally prefer the idea of a NC contactor that is powered off the grid L/N and connected to the load N/E that way when the grid drops it closes and creates the internal N/E bond.

49 minutes ago, RocketBoy said:

Question 1.

What amp rating of contactor should be used to create the earth/neutral bond? Does it need to be a high current 60A 230v or will a 6A 230V work fine? Does it even need to be a contactor or will a relay suffice?

I ended up buying a 45A contactor based on what seems the recommendation in the SunSynk earth bond manual for 8KW units (5KW units: 32A) - page 4.

It's NO (I think it has a couple of NOs). However, given its size while it fits a rail but wont fit a standard DB enclosure, so I still need to buy a separate deeper box for it to mount alongside the AC box. 

Here is a 20A contactor that fits a standard din db. If you bridge the 2 poles does that equate to 40A?

https://www.robotics.org.za/CT1-25?search=contactor

 

3 hours ago, Kalahari Cruiser said:

I ended up buying a 45A contactor based on what seems the recommendation in the SunSynk earth bond manual for 8KW units (5KW units: 32A) - page 4.

It's NO (I think it has a couple of NOs). However, given its size while it fits a rail but wont fit a standard DB enclosure, so I still need to buy a separate deeper box for it to mount alongside the AC box. 

Keith from Sunsynk laughed in his one video when they handed him a 40A contactor because he said its massively overkill. 

I still dont understand why they dont just supply one with the inverter that is the correct spec for the unit. They supply pretty much everything else.

You would want the earthing contactor to handle the maximum current of the inverter. Perhaps a smaller relay will work if all loads feed of an earth leakage... a 2.5mm² bridge works like a charm for me.

21 hours ago, Thunderdolt said:

Here is a 20A contactor that fits a standard din db. If you bridge the 2 poles does that equate to 40A?

https://www.robotics.org.za/CT1-25?search=contactor

 

Thanks the link. They also have another din rail relay for R50 with 10A contacts. 

Yes you can get just under 40A using both contacts. After time if one contact is dirty the current will be reduced and  lead to burning of the good contact. 

Edited April 6, 20231 yr by Scorp007

2 hours ago, Scorp007 said:

Thanks the link. They also have another din rail relay for R50 with 10A contacts. 

Yes you can get just under 40A using both contacts. After time if one contact is dirty the current will be reduced and  lead to burning of the good contact. 

Hopefully it will never carry any current of significance!

see https://diysolarforum.com/threads/deye-16k-and-sunsynk-neutral-earth-ground-bonding-in-signal-island-mode-howto.55812

The device fits a DIN rail in a distribution box and here in the UK costs £15 from amazon

 

Edited April 6, 20231 yr by Lactophobe

On 2023/04/05 at 12:34 PM, RocketBoy said:

Question 3.

Which configuration of relay/contactor is best Normally Open or Normally Closed?

Normally Open (NO) for Deye inverters. I would however recommend a 2P 1NO+1NC 250Vac contactor just in case signal island mode works contrarily to what is described in the manual. See this post for more details.

The choice of a Normally Open contactor is guided by the fact that terminals "ATS 240" will only show 0Vac (zero volts AC) when grid is ON and "Signal ISLAND MODE" is checked as per the truth table below.

Deye ATS 240 Truth Table
Grid	Signal ISLAND MODE	ATS 240
0	0	1
0	1	1
1	0	1
1	1	0

Note that if "Signal ISLAND MODE" is unchecked, then terminals "ATS 240" will have 240Vac (could be 218-230Vac) at the output irrespective of whether the grid is ON or OFF

Still on Deye inverters, beware of a bug that inadvertently unchecks "Signal ISLAND MODE" whenever the menu "System Setup Menu" -> "Grid Setup Menu" is navigated.