Generator clarification

[flyingsparks]

house supply is tn system
6kva Generator is to be used as a backup.
The generator chassis is connected to the chassis of the generator.
There is no connection between neutral and Earth on the generator.
The picture below is how I believe it should be connected but would appreciate if this could be clarified. It's been a while since I did a generator supply!

 

[Risteard]

There is no connection between neutral and Earth on the generator.

An unearthed pole is not, by definition, neutral!

 

[flyingsparks]

Nit picking!

 

[ericmark]

Many generators have links between winding a chassis inside the unit. This link is not always to a star point or to winding end, the 55 - 0 - 165 is all too common with duel voltage units. As a result one should make any chassis winding link on the generator not external to the generator. That way if the generator is swapped you can't get two links which are to different points on the winding.

Be it a generator or a inverter or isolation transformer one has to think hard about any links to earth. The link could result in one earth which has a different voltage to another earth, with large commercial premises they have massive resistors between local generator earth and grid earth. I don't like the IT system, but it could be safer than TN or TT in some cases. The supply from a shaver socket for example.

It is common to find UPS with an IT output when mains has failed, at 32A I would like to see a TN-S system, but it's not a cut and dried thing. The monitors for IT systems are expensive, so converting the generator to TN-S is the best option in most cases.

6kVA at 230 volt = 26 amp, divide this by 5 = 5.2 amp so the largest MCB which you can guarantee will trip on the magnetic part is 5A. I would be looking at a fuse not an MCB a 25A fuse maximum, but depends on the generator some will loose their field with over load, some will burn out, and some the engine becomes overloaded.

 

[flyingsparks]

Would you say the earthing I have drawn is the correct way about it then?

 

[JohnW2]

Would you say the earthing I have drawn is the correct way about it then?

Since eric seems to be favouring a 'TN-S' arrangement, I assume that he would like/want you to connect the 'earth conductor' (that going to your 'earth block', in turn connected to your earth electrode) to one side of the genny output (which, to satisfy Risteard, would then become the 'neutral'). That's virtually what you've drawn, but maybe eric would favour an even more 'direct' N-E connection at the genny?

Kind Regards, John