RCB inverter

[Lady A]

I am sorting out the shore power and a 600 watt pure sine inverter on Lady A. The shore power comes in via a socket on the outside to a fuse box with a 30 milliamp RCB. It then feeds 13 amp sockets and a Sterling battery charger (3 batteries, 2 domestic 1 engine). The earth goes through a Galvanic Isolator and bonds to the negative on the engine block and then to the fuse box.

 

Now I am thinking of wiring the mains through a relay the coil of which is energised by the shore power. So when connected to shore power the relay operates and supplies current to the sockets. When Shore power is off the relay switches to the output of the inverter. (The charger will be wired to the mains so that it only operates with shore power.

 

Question is 'should the 240v out of the inverter also go through its own RCB'?

 

Any other thoughts would also be appreciated...

 

Martin

Edited April 11, 2007 by Dhutch
Corrected typo in heading.

[Chris J W]

On the face of it, I would have thought a proper control system would be much safer and simpler to install.

[Big Steve]

It sounds like the inverter is going to supply the same sockets as the shore power, so it must be going through the same RCD? Just make sure the relay is heavy enough and has the correct contact spacing for this job. I've a vague recollection that it has to be at least 3mm.

[Lady A]

It sounds like the inverter is going to supply the same sockets as the shore power, so it must be going through the same RCD? Just make sure the relay is heavy enough and has the correct contact spacing for this job. I've a vague recollection that it has to be at least 3mm.

 

 

Problem is that if it was giong through the same RCB the battery charger would be in the loop as that is after the RCB so i would need to organise more relays to disconect that if the shore power was off.

[NB Willawaw]

Does the inverter in question allow its case in the form of a PE terminal, to be connected to the boats Ground (Earth) Point ??

It is usual to install an RCD/RCCB between inverter and its switching (relay or manual changeover switch) to the circuit its supplying, so if the inverter

can be grounded, I would fit a second dedicated RCD/RCCB on the inverter output.

 

In practice, most of the devices you would run using a 600VA inverter would probaly be double isolated (PC/phone/small TFT TV etc), but the text book answer is its normally required.

Edited April 8, 2007 by NB Willawaw

[chris w]

Take a look at Gibbo's site. He has some excellent diagrams for wiring up AC shore power and inverters etc with virtually any combination you could imagine.

 

click here

 

Chris

[Lady A]

Take a look at Gibbo's site. He has some excellent diagrams for wiring up AC shore power and inverters etc with virtually any combination you could imagine.

 

click here

 

Chris

 

 

Good stuff. Thank you.

 

Martin

[PeterF]

I would fit a second dedicated RCD/RCCB on the inverter output.

 

I have just installed a small inverter for LCD TV and my son's Nintendo Wii and installed an RCB, the inverter supplies dedicated sockets for these so no cross over to shore power to worry about. I tried it at home off my car battery without the RCB and the TV and games machine both worked fine. But when installed on the boat with the RCB the inverter buzzes and so does the TV sound but picture is fine. It is modified sine wave inverter so could this be causing some form of "interference" (I know it is not the right word) with the RCB.

 

Any thoughts would be welcome.

 

Peter.

[NB Willawaw]

What kind of inverter is it ?

 

 

I have just installed a small inverter for LCD TV and my son's Nintendo Wii and installed an RCB, the inverter supplies dedicated sockets for these so no cross over to shore power to worry about. I tried it at home off my car battery without the RCB and the TV and games machine both worked fine. But when installed on the boat with the RCB the inverter buzzes and so does the TV sound but picture is fine. It is modified sine wave inverter so could this be causing some form of "interference" (I know it is not the right word) with the RCB.

 

Any thoughts would be welcome.

 

Peter.

[chris w]

I have just installed a small inverter for LCD TV and my son's Nintendo Wii and installed an RCB, the inverter supplies dedicated sockets for these so no cross over to shore power to worry about. I tried it at home off my car battery without the RCB and the TV and games machine both worked fine. But when installed on the boat with the RCB the inverter buzzes and so does the TV sound but picture is fine. It is modified sine wave inverter so could this be causing some form of "interference" (I know it is not the right word) with the RCB.

 

Any thoughts would be welcome.

 

Peter.

Are the inverter earth and the mains sockets earths all connected together at one point, this point itself being connected to the hull?

 

Chris

[ChrisPy]

answer to the original question ................... yes.

 

IMHO.

 

...... and no need for extended debate, I would have thought.

[PeterF]

Gents,

 

Inverter is a Nikkai (basic) 600W with TV and games console taking about 150W. The inverter is earthed to the hull and the sockets will earth back to this point through the connnection to the inverter.

 

Peter.

[NB Willawaw]

I can't think of anything obvious and I can't understand how the inverter would react with the RCD to give these symptoms.

There may be some other characteristic that is different between your garage set-up and the boat set-up.

 

If it were my boat, I would check the DC lead to the inverter is as short as possible and test the circuit on the boat momentarily without the inverter earth lead connected and without the RCD in circuit, to see if the symptoms change. I would stress, without trying to sound pompous or patronising that this is dangerous because mains electricity is involved and the RCD is your protection, so doing this would be at your own risk and if you are in any way unsure of the principles involved, you would be better advised to leave well alone.

 

Gents,

 

Inverter is a Nikkai (basic) 600W with TV and games console taking about 150W. The inverter is earthed to the hull and the sockets will earth back to this point through the connnection to the inverter.

 

Peter.

[NB Willawaw]

Its a bit of a long shot, but just make sure that your boat battery is well charged. It might be worth running the engine when you check the inverter operation.

Normally low batt volts on an inverter don't manifest themselves in this way, but electricity can do strange things sometimes, so its another possible cause excluded.

 

I have just installed a small inverter for LCD TV and my son's Nintendo Wii and installed an RCB, the inverter supplies dedicated sockets for these so no cross over to shore power to worry about. I tried it at home off my car battery without the RCB and the TV and games machine both worked fine. But when installed on the boat with the RCB the inverter buzzes and so does the TV sound but picture is fine. It is modified sine wave inverter so could this be causing some form of "interference" (I know it is not the right word) with the RCB.

 

Any thoughts would be welcome.

 

Peter.

[PeterF]

Mark,

 

Thanks for ideas. It still buzzes when the engine is running. When inverter is on and the RCB is on the inverter buzzes even if no load is being taken. However, when the inverter is on and the RCB is off the buzzing stops. I have not tried your ideas re earth connection and bypassing RCB, may do at the weekend or I may just try another make of RCB to see if that eliminates the problem.

 

Cheers.

 

Peter.

 

Its a bit of a long shot, but just make sure that your boat battery is well charged. It might be worth running the engine when you check the inverter operation.

Normally low batt volts on an inverter don't manifest themselves in this way, but electricity can do strange things sometimes, so its another possible cause excluded.