How is a generator earthed and given neutral?

[assegayer]

Hi

I have a question i cant seem to get an answer too.

If you have a portable generator and you plug for instance a fridge or any appliance directly into it, how is the neutral/earthing provided??

I know already that normally you can connect the neutral and earth from an existing installation

But what if you are for example somwhere random and i plug a fridge into a generator where is the neutral coming from? Surely it cannot be from the casing as if someone was to lift the generator up they would get a belt from the supposed to be neutral return path?

Thanks in advance

 

[Ian1981]

Hi

I have a question i cant seem to get an answer too.

If you have a portable generator and you plug for instance a fridge or any appliance directly into it, how is the neutral/earthing provided??

I know already that normally you can connect the neutral and earth from an existing installation

But what if you are for example somwhere random and i plug a fridge into a generator where is the neutral coming from? Surely it cannot be from the casing as if someone was to lift the generator up they would get a belt from the supposed to be neutral return path?

Thanks in advance

 

[assegayer]

Thanks for the reply but what i still dont understand is where is the neutral in the generator getting its ground from? At the end of the day neutral is ground

 

[Ian1981]

Thanks for the reply but what i still dont understand is where is the neutral in the generator getting its ground from? At the end of the day neutral is ground

The neutral is not referenced to earth in a portable generator the generator supply is unearthed
a protective conductor must connect the exposed conductive- parts of the generator frame (and its enclosure) to the exposed conductive parts of the equipment being supplied. No exposed conductive part of the separated circuit is to be connected to any protective conductor or exposed conductive parts of other circuits or to Earth otherwise the protective measure of electrical separation fails

 

[assegayer]

This is what i am struggling to understand. Then how does the circuit work! Where is the neutral connected in the generator?!

When normal electric is generated you have a star point and that is grounded thus u get your neutral off that point you dont just get a neitral from anywhere its earthed???

 

[Ian1981]

This is what i am struggling to understand. Then how does the circuit work! Where is the neutral connected in the generator?!

When normal electric is generated you have a star point and that is grounded thus u get your neutral off that point you dont just get a neitral from anywhere its earthed???

The neutral in normal cases gets its 0v potential from being earthed at the star point which in this case is pointless as you are relying on Electrical separation as your protection against electric shock a ‘floating earth’

 

[assegayer]

What is a floating earth?

 

[Ian1981]

What is a floating earth?

The generator supply is unearthed.
The appliance and generator case are earthed.
If you have an earth fault you can’t receive an electric shock as there is no earth return path to the origin ie the generator windings so no electric shock.
The means of Electrical separation is only allowed on one item of equipment

 

[assegayer]

Okay that is fair enough but

Where is the neutral connected in the generator?

 

[Ian1981]

Okay that is fair enough but

Where is the neutral connected in the generator?

The windings see the above illustration.

 

[assegayer]

Sorry if it sounds like its a wind up it honestly isnt..

But wouldnt that cause a short circuit having neutral and live on the same winding?

 

[HandySparks]

Sorry if it sounds like its a wind up it honestly isnt..

But wouldnt that cause a short circuit having neutral and live on the same winding?

Think of the generator winding in the same way as the output winding of your local DNO transformer. They're both just a coil of wire sitting in a magnetic field, with neutral at one end and line at the other.

 

[kingeri]

Think about the negative terminal on a battery as well, the circuit works but it ain't earthed!

 

[Davisonp]

Does this help?

 

[Deleted member 26818]

Basically, an unearthed single phase generator has no neutral. It has two lives and together they add up to 230V.
If you then Earth one of the lives, that will become the Neutral.