Impedance Testing ,

[Fordean]

Xray supplier, Has requested the Z values are to be check at three separate points, What type of instrument/procedure should be followed. Job was designed and they informed us after the fact.


Have a 180 foot 4wire (4/0- # 4G) To Main 480 Volt Panel Fused at 200. Then to two different points for the xray unit..
There is no Transfromer. We are cannot To Bus Bar type assembly that travels up the Tower.



I will upload a photo if anyone requests.

Thank You

 

[junkhound]

2 channel scope is easiest
2 different known loads, take voltage and current and phase relationship, plus open circuit with small resistive load.

calculate impedance

 

[Tony S]

A MFT will do this for you quite easily giving Ze or Zs depending where you test.

Believe it not, they standard tests for any installation this side of the pond.

 

[Tony S]

This is the type of meter I was referring to. It will do Zs, Ze and Zpn as well as IR and CR.

http://www.test-meter.co.uk/metrel-...tion-tester/?gclid=CM2v16XT2sUCFWuWtAodiVsA9A

 

[ramsy]

This is the type of meter I was referring to. It will do Zs, Ze and Zpn as well as IR and CR.

http://www.test-meter.co.uk/metrel-...tion-tester/?gclid=CM2v16XT2sUCFWuWtAodiVsA9A

have you seen a trip tester for domestic 120v circuit breakers?

 

[Tony S]

The OP was about the three readings required for Z.

Ze, Zs and Zpn are the ones I know of, are there others?

It would have helped if the OP had included the manufacturers required values and some detail.

 

[Fordean]

Load Values,

Load Values,

The OP was about the three readings required for Z.

Ze, Zs and Zpn are the ones I know of, are there others?

It would have helped if the OP had included the manufacturers required values and some detail.

Yes, There are 3 Required. I believe ZL, ZT, ? I will upload drawings. ZT is at Trans, ZL may be Load, and third was at disconnect means I think, I will load more data. Since I am getting good response here. My reason on posting, IS the Xray company Stated it WILL NOT hook up if values aren't within specs. This job went thru many levels before the go ahead, And I am not sure if the Engineer even had these values, ( Since we were given at the Job meeting). But bid job without them, Because we were never given those 3 sheets.

 

[pjholguin]

I would like to see your project photos.

Thank you

Xray supplier, Has requested the Z values are to be check at three separate points, What type of instrument/procedure should be followed. Job was designed and they informed us after the fact.


Have a 180 foot 4wire (4/0- # 4G) To Main 480 Volt Panel Fused at 200. Then to two different points for the xray unit..
There is no Transfromer. We are cannot To Bus Bar type assembly that travels up the Tower.



I will upload a photo if anyone requests.

Thank You

 

[Tony S]

Yes, There are 3 Required. I believe ZL, ZT, ? I will upload drawings. ZT is at Trans, ZL may be Load, and third was at disconnect means I think, I will load more data. Since I am getting good response here. My reason on posting, IS the Xray company Stated it WILL NOT hook up if values aren't within specs. This job went thru many levels before the go ahead, And I am not sure if the Engineer even had these values, ( Since we were given at the Job meeting). But bid job without them, Because we were never given those 3 sheets.

I will reply this evening (its mid day here). It will be easer if I knock a quick drawing together as the terminology we use is different to you. A pictures worth a 1000 words as they say. The principal is the same where ever we are.

 

[Tony S]

Sorry this has taken so long. I?m supposed to be retired and have been on the damn phone for 3 hours with everyone else?s problems.

You will need to beg, borrow, steal or even hire a loop impedance tester. The meter I listed earlier has it built in but thinking about it I?m not sure how it would cope with your crazy systems.

Until I sat down to do this drawing I hadn?t thought of the extra tests a three wire system involves.

TP1/5 will give the supply impedance, from this you can calculate your Maximum Prospective Fault Current. TP6/10 will give you the impedance at the load and again the MPFC. Along with the integrity of the GEC by giving it an actual value, this is what the X-Ray equipment manufacturers will be concerned with.

These are standard tests for a UK domestic installation, commercial/industrial it gets worse.

 

[zbang]

]TP1/5 will give ...

In more common usage over here- "TP1-5" or "TPs 1-5"; the slash/stroke took me a moment, I first read that as 1 and 5, not 1 through 5. Of course, the picture did make it clear what you meant.