Grounding Generator and Transformer Neutrals Separately in Yd Step-Up Setup: Risks?

Hello,
Please explain,
Generator, STAR connection, 400V.
Step Up transformer Primary side is STAR, low voltage (400V)Secondary side is Delta, High voltage (15.000 V)
Is it possible to ground the star on the generator side and ground de star on the transformer side, and have no cables between the neutral of the generator and the neutral of the transformer ?, what could be the problems and risks ?.
Generator                                                                           Setup Up Transformer (Yd)L1--------------------cables-------------------L1L2--------------------cables-------------------L2L3--------------------cables-------------------L3N---Ground                                                                   Ground----N

Thank you.

Hi Richard,
No you cannot ground at both points. The ground connection is only used to carry earth fault currents back to the source of supply. While yes the ground cable is connected at the neutral at some point therby making it the same as a neutral, it is not a neutral. The neutral is there to continuously carry current back to the star point due to unbalanced loads. What you are taking about would require those currents to pass back through the ground cables which probably wouldn't be sized correctly to be used as a neutral. Creating heating issues with the earth cables, most likely voltage issues on phases due to the poor reference "neutral". And you could have situations where a person touching exposed metalwork (your makshift neutral) and other metal parts could become part of the circuit, creating a lower resistance path for current to flow. That brings me to another point, the earth leakage protection would be either useless or would be giving you nuisance trips. All situations that could and should be avoided.

Hi Gallagher,
So that means that i can not avoid to install cables between  the two neutral points ?.As the generator is far from the step up transformer and in the secondary is delta type, i would like to save money.
Generator                 TransformerL1  —————————L1   L2 ————————— L2L3   ————————-   L3N                                           N——-groundPE ——ground              PE——-ground
Also no good ?
Thank youBest regards

If you don't connect a neutral to your generator, it would effectively be connected in delta. You should really speak to an electrical design engineer who knows your specific countries electrical rules and regulations before you go ahead with this. The cost saving  of not running the neutral now is not going to cover the cost of rework when things don't work correctly during commissioning and it is decided that you now need to run a neutral.

ok, Thank you.