Grounding transformers

[luischavez]

Someone knows how to calculate zig-zag reactor:
- Zero-qequence impedance
- Rated continuous neutral current
- grount-to-earth shortcircuit in systems with zig-zag reactor

Thanks

 

[busbar]

 
Long shot reference...

ANSI/IEEE Std C62.92.4-1991 …Application of Neutral Grounding in Electrical Utility Systems, Part IV—Distribution

Annex A Specifying a Zig-Zag Grounding Transformer

 

[jnims]

This standard busbar referenced is good. Another standard you should review if you are specifying a grounding transformer is:

ANSI/IEEE Std 32 IEEE Standard Requirements, Terminology, and Test Procedure for Neutral Grounding Devices.

A good application reference, with examples, is:

"Neutral-Deriving Transformers for Grounding Low Voltage Systems with Delta-Connected Source Transformers," R. L. Smith, IEEE Transactions on Industry Applications, Vol. IA-18, No. 2, March/April 1982.

While you don't mention any interest in the associated protection schemes, I will also throw in

"Grounding Transformer Applications and Associated Protection Schemes", E. R, Detjen and K. R. Shah, IEEE Transactions on Industry Applications, Vol. 28, No. 4, July/August 1992.