X/R Ratio for Grid/Utilities

<...find typical X/R ratios for Grid/Utilities...>

Using Google.

Mike Holt puts out good information in a very understandable format. He is certainly one of the better one's out there, if not the best.

Volts out / volts in will give a ratio.

How many turns is a different matter but you didn't ask that.

Learn how to search the internet.

You found us,so you have some knowledge of searching,however it only took less than 1 minute to find the link below ,which will provide the answers to your question.

This is free the first time.

But be aware that you are wasting other's time by asking for easily available answers.

Perform a diligent search first.

http://www.transmission-line.net/2011/02/importance-of-xr-ratio-in-low-voltage.html

I am just commenting as a way of bookmarking the discussion as it is at least of more than passing interest in a power generating station. Here we have lower X/R than some, since we are near the source, and the power factor here is well-known, maintained at a high value.

From General Electric Application Information. Short-circuit Current Calculations. Appendix X/R Ratios ( From ANSI Standard C37.010):

E. Utility source

1.Near generating plant Range: 15-30

2.Long open-wire line Range: 2-16

3.Typical Range: 5-12

Thank you everyone for your comments. Before asking the question here, I had already exhausted each and every link provided in your answers.

I need the X/R ratio for the incoming grid power. My problem is that I've no details on the substation in question other than its voltage level and fault MVA. The utility people are also not able to provide me any more data (like the pf or resistance & reactance values) that I can use to derive X/R.

And since the substation is in a different country than what I belong to, it is not possible for us to determine how far from the generating station is the from the said substation. So the range given in ANSI C37.010 has not been very helpful.

So, again (wasting some more of your time ), is there any other way I can get X/R using just the available data. I want to use the most accurate value possible.

Thanks again.

A typical tendering problem!

A system study can only be as good as the ingoing information permits. You could assume the worst case and tell the customer so, citing the sources you have tried without result. Is this just one unknown in a well specified system so you can re-run the analysis for minimum & maximum values to see if it really matters?

How could we help when you have not even told us the voltage and fault level (and frequency) you know?

What difference does X/R make to your substation? Are the critical values to come out of your study at the substation, or is the substation a small item in the system?

I would guess that high X/R, being more inductive, would be more difficult to break and could require a better breaker or fuse (more cost). But a safe and effective solution would result.