Earthing the Neutrals of Y-Y Power Transformers
Earthing the Neutrals of Y-Y Power Transformers
(OP)
I have the following scenario (in South Africa): a utility power transformer (132/33 kV) is star/delta with an NECRT on the secondary side (limiting to 300 A). I must install a star/star transformer downstream for 33/11 kV supply to a load. What must I do with the two neutral points of my transformer?
I initially want to put an NER connected to the secondary star point and leave the primary star point open...
What are the opinions out there?
I initially want to put an NER connected to the secondary star point and leave the primary star point open...
What are the opinions out there?






RE: Earthing the Neutrals of Y-Y Power Transformers
1. What is the need of a NER at the 11 kV end?
2. Is it not possbile for you to use a detla-star transformer in stead of a star-star? Cause the phase shift casued by the upstream transformer will not getting nullified at the load end with the use of a star-star transformer.
RE: Earthing the Neutrals of Y-Y Power Transformers
We must use a star/star to avoid any phase displacement, since there is a possibility that other transformers can be swithced in parallel with this one.
RE: Earthing the Neutrals of Y-Y Power Transformers
Regards
Marmite
RE: Earthing the Neutrals of Y-Y Power Transformers
11kV winding - grounded via a reactor or a resistor if you do want to limit the L-G fault.
RE: Earthing the Neutrals of Y-Y Power Transformers
Regards
Marmite
RE: Earthing the Neutrals of Y-Y Power Transformers
.....a utility power transformer (132/33 kV) is star/delta with an NECRT on the secondary side (limiting to 300 A). ....
What is NECRT?
I guess,33kV delta is the secondary. It is not?
RE: Earthing the Neutrals of Y-Y Power Transformers
Regards
Marmite
RE: Earthing the Neutrals of Y-Y Power Transformers
RE: Earthing the Neutrals of Y-Y Power Transformers
A scenario (in Brazil): a utility power transformer (138/69 kV) is star(solid grounded)/delta with zig-zag transformer on the secondary side (limiting to (3< X0/X1 < 10). downstream transformer will 69/13,8kV delta/star solidly grounded).