Civil detail & clearances for 160kVA Trafo

[GadreP]

Dear Friends, I have a step-up transformer of 415/11000V, 160kVA. Can anybody provide me information on civil details? I basically need the height of foundation from FGL & how much clearance is required on all the 4 sides of transformer. Also I need to install a DG set (160kVA, 415V) in periphery of said transformer , so what distance is required to be maintained between transformer fence & DG set? Does 160kVA transformer require oil containment pit?

 

[qqitek]

Hi GadreP,

generally, the main objective that shall be concidered is fire security requirements. I guess that trafo is oil filled, right?

You must determine oil containment volume (oil m3 -from vendor), distances from nearest objects (fire separation), clearances on HV/LV side (voltage separation), any access road (on rails, or on the platform).

For fire distances from other objects NFPA850 chapter 5 is good reference.
For distances IEC 60071, Annex A, Table A.1 can be referred. But this is for HV, I do not remember if for MV also. Check it out.

regards
qqitek

 

[7anoter4]

Following the qqtek recommendations NFPA-850 seems to be suitable.
nevertheless the standard is not recommended for general purpose but:
NFPA 850, Recommended Practice for Fire Protection for Electric Generating Plants
and High Voltage Direct Current Converter Stations,
Your transformer is filled [usually] with approx. 250 l [far from 1890 l] so NFPA-850 ch. 5.2.4.3 does not require
a fire wall to be provided for outdoor installation but if it is indoor installation you have to provide 3 hour fire resistant wall.
In connection with spilled oil evacuation ch.5.6 Drainage could be an indication.
I don't think IEC 60071 INSULATION CO-ORDINATION would add here something.
Annex A "Clearances in air to assure a specified impulse withstand voltage installation"
It covers three-phase systems with nominal voltages above 1 kV.
I think NFPA-70 [NEC] art 420.26 for indoor installation and 420.27 for outdoor installation is more suitable for a general purpose transformer.
You may also take a look of National Grid Specification [for bid]:

http://www.nationalgridus.com/niagaramohawk/non_html/constr_esb754759.pdf

 

[prc]

Some of the details desired are given in IEC 61936-1(ed2.0) 2010-08.Power Installations exceeding 1 kV AC Part 1 Common Rules
Transformer installation rules are given in clauses 4,5,8 and 6.2.2

Clearance on all sides for 11 kV- 3 metres
Clearance between fence and DG set - 1.5 metres
OIl pit requirement varies country to country.For this size of trf,it is not provided.