220 kV Outdoor substation layout. Distances between equipment

[radug]

Hello,

I need information about how to calculate the minimum distances between current transformers, voltage transformers, surge arresters, power transformers and circuit breakers in outdoor 220 kV substations.

I have done an insulation coordination study and have the minimum phase-to-earth and phase-to-phase distances, but how to obtain the design or layout distances?

Can anyone give references to standards or design guides about it?


Thanks.

 

[jghrist]

Where are you? Do you need IEC or ANSI standards?

 

[radug]

Hello,

Any of them would work. Is is for a substation in Mexico, their standards are a mix of IEEE and IEC.

 

[jghrist]

ANSI Std. C37.32-1996 and NEMA SG-6-1995 have recommended clearances. The NEMA standard has been withdrawn, but tables based on this standard are in RUS Bulletin 1724E-300, Design Guide for Rural Substations which is available at

http://www.rurdev.usda.gov/RDU_Bulletins_Electric.html

 

[radug]

Thank you. I did not know about them. I will have a look.

 

[Yjoshi]

Radug, If you are working in Mexico I believe that you should be aware of CFE standards and they use 230kV instead of 220kV, maybe this could help

http://www.sisi.org.mx/jspsi/documentos/2003/seguimiento/18164/1816400029303_065.pdf.

We just finish building an small 115kV/13,8kV 30 MVA substation and they were very firm regarding their standards and to make it even more interesting, they had different dependencies with different specs among them (I don’t think these differences will change the switch yard layout but we had some problems regarding the gates and other minor stuff that not addressed at an early stage will definitely impact your profit)

 

[radug]

Hello Yjoshi,

Thanks for the document. I am aware of CFE standards. A supplier sent me a 1988 year CFE document with distances between, surge arrester, voltage transformer and current transformer of 5 m, and 10 m to the power transformer. And phase-to-phase distances of 6 m.

I have not found such long distances for 220 or 230 kV. I tried to locate the 1988 year document in CFE website, where their specs and standards are freely available for download and could not locate it nor anything similar. That is why I am trying to locate some standard about recommended distances in outdoor substations.

I find CFE standards to be a mix of IEC and IEEE. They are mainly based in IEC for design, but equipment is mainly based in IEEE, so it is quite a mess.

 

[cuky2000]

Beware of the following:
- ANSI & IEC standards have differences in clearance requirement.
- ANSI standard voltage is 230 kV and IEC std voltage is 220 kV. Standard BIL rating is also different.
- CFE use live tank breakers. Dead tank design is popular in the ANSI marketplaces and not common in Mexico.

I guess both standards will work OK for 220 kV. However, for local compliance and avoid surprises, check in advance for approval with the utility and anyone that has jurisdictions with your project.