ze,

[Kennysparky]

Hi folks. I am looking for some guidance regarding ze, short circuit current and earth fault current tests.

I have been asked to do some tests on a hazardous area site for an engineer that is doing an AMTEC survey for additonal ccts.

The site has its own 150kva 1to1 transformer a 160kva standby generator and a number of earth nests which are all interconnected.There is no earth supplied by REC.

The engineer requires a ze, prospective short circuit current, and prospective earth fault current for input side of transformer, output side of transformer and standby generator.

I am unsure of correct proceedure for such an installation with regards to disconnecting earths, testing on supply side where there is no earth and testing generator etc ( the generator earth is connectedto main site earth bar/rods ) also could I cause damage to internal components of generator by doing these tests.

I may also have a problem with introducing potentials onto metalwork in the hazardous area.

 

[Engineer54]

So, your doing testing work that you have very little idea of how to conduct, and to make things worse this work is in a known Hazardous Area!! Apart from anything else, do you happen to be in possession of ''Intrinsically Safe'' test equipment, or CE certified test equipment for safe use in hazardous areas?? More importantly does your insurances cover you for working in such area's???

Seriously, ......I would pass this work module on to someone that has the necessary experience and test equipment. Then help him conduct these tests so that you will at least learn something out of this exercise.

 

[Deleted member 26818]

I'm with Engineer on this.
This is not something that I would allow someone with little or no experience to conduct.

 

[Kennysparky]

I am el6 authorised and obtaining advice and guidance from senior engineers. Just thought it might be interesting to read your views on on this subject as it is not a simple' isolate at main switch and disconnect the earth'. Normal procedure for haz areas is to do a ze at main switch and calculate zs for each circuit. I have no intention of carrying out these test until I am competent to do so. I do have an i.s insulation and continuity testers and a fluke multifunction tester. The transformer,genny and REC supply are all in a safe area.

 

[netblindpaul]

Kenny,
That is not how your OP came across!
Now I don't do anything ATEX, so have no real idea, but, if you had put this info on your OP then you would not have had the replies you got.

BTW, what's el6?

 

[Kennysparky]

el6 is a certification scheme that allows you to carry out electrical work in hazardous areas. Basicaly means you have to do a number of compex courses etc then go for an interview. One of the main teachings of el6 is not to do anything you are not trained or competent to do, hence why I was seeking views from other electricians on the subject.