Transformer Neutral grounding

A

Thread Starter

Alexander_giorgian

Hi all,

I want to Know, how can I calculate resistance or reactor for neutral grounding of one transformer with following data:
33Kv/7.07 KV
Yd
UK%=7.1%-9%
20/25 MVA
 
P

Phil Corso, PE

Responding to A. Giorgian's Oct 12, 4:20pm query... additional information is required:

1) Is the Wye connected primary, 33kV, supplied from an overhead transmission system?

2) Is the Delta connected secondary, 7.07kV, earthed via an earthing transformer?

Regards,
Phil Corso, PE {Boca Raton, FL, USA}
[[email protected]] ([email protected])
 
S

Sushanta Halder

First you have to decide the earth fault short ciruit current to be limited to a value say 100Amp (equal to rating of generator gounding resistor current rating). Then the phase voltage will be appeared will be 33/1.732 kv. so the resistor value will be 33/(1.732*100)=X kohm.
 
Top