Out of my depth

[nunthe wiser]

I was asked to install a small consumer unit at the end of step down transformer. The consumer unit is fed from a panel board put in place for a future wind turbine project . The consumer unit feeds a socket and a light. This is all in a metal container that is earth roded with bare tape and rods. Now I checked my voltages at my income r of panel board and everything was okay apart from one phase was 20 volts higher than the others with respect of earth and neutral. I connected up my board to test my loop impedances and when a load goes on the board the neutral reaches 3 phase voltage when measured to other phases and 240 to earth. I figured the neutral must be gone but when measuring with no load on system everything seems fine . From the transformer plates they are delta delta and the neutral is through crimped. I'm told the reason for the step up - down transformer is because upsizing the cable would cost the same but would impossible to work with. I have no knowledge of design of this level of work, should the neutral be larger and,as it is it's to high a resistance for a return. It's got me stumped and it was supposed to be a simple job. Long winded I know.

Thanks for all help given

 

[Pat H]

Yes by stepping up the voltage the current drops so smaller CSA can be used. Makes sense.
The OP stated the step down was delta. Could it be delta on the primary and star on the secondary?

 

[westward10]

Yes by stepping up the voltage the current drops so smaller CSA can be used. Makes sense.
The OP stated the step down was delta. Could it be delta on the primary and star on the secondary?

To enable a neutral you would need star secondary, it sounds like he has delta secondary but a view of the plate would be handy.