Power Transformer Neurtal Earthing

You will need to educate me here first - what is a Primary S/S and why do you have a neutral on the HV side of an HV transformer. I assume that you are not in the UK.

Here we don't have neutrals in the HV system if the primary winding of an HV transformer is 3 phase Delta wound then there is no there is common point to earth, only the Star wound winding would have a common earthed reference point. The neutral is only derived at the secondary side winding of the HV/LV distribution transformer.

The primary winding of an remote transformer will be protected by a protective device immediately adjacent or at least at the outgoing line from the Generator station.

U are right, for HV with delta connection no need neutral earthted , but Grounded should be. For grounded you can find cable NYFGBY for direct grounded between generator till distribution tranformer. ofcourse protection devices must be install.

Sir, can u give expansion for NYFGBY

I can't tell you, but I do know a guy who might. Please note I believe that he is right now busy connecting up a new substation, so he maybe hard to get a hold of.

Steven Watts:

wstephens@clarkenergy.com

Fax: 859-744-4218

Phone: 859:901-9209

You need to calculate the fault current first based on the fault level at the receiving point.Then find out the touch and step potentials which will arise at the instance of fault and these need to be limited to below safe limits .Solid grounding can cause full fault current to flow and can give rise to dangerous levels of touch and step pottential.It is advisable to use a neutral grounding resistor ( Value to be calculated)to limit the fault current values.Details can be had from any electrical hand book.If u are from India refer to TNEB hand book.

best of Luck

Dear,

As one of the guests pointed out how do you have neutral point on your HV
transformer? You are supposed to have DELTA AND NOR STAR for HV transformer
in a generating station that is what we read in our Electrical Engeering. However
whatever the case may be you should be providing a LOWEST POSSIBLE RESISTANCE
PATH for earthing. I wonder why are you talking about resistance at all.

R. GANAPATHI RAO, INDIA.
(ganapa@cdotb.ernet.in)

The following points need to check before goint for Neutral Grounding Resistance.

1. Fault current passing through groung, step and touch potential.

2. Capacity of transformer to sustain ground fault current, w.r.t winding, core burning. Manufacturer shall be able to give this data.

3. Relay co-ordination and fault clearing time.

4. Standard practice of limiting earth fault current. In case no data or calculation is possible, go for limiting E/F current to 300A or 500A, depending on sensivity of relay.

Further to the above you can go-through E/F protection topics in IEEE buff book.

BNDas

The best way to get an answer to your question is to take a look in IEEE standard C57.116-1989.

If you need an issue of it, please do not hesitate to contact me:

elbf2801@hotmail.com

Regards

i think you are speaking about delta-delta trf.you can use neutral earthing trf to get neutral point.