VLF test of MV/HV cables

[slavag]

Dear All.
I would like ask you some not correct Q.

On this week-end (Merfi law) we had several faults on the MV cables in the same factory and I'm looking for explanation in the forum.
I found many posts about HIPOT, PD tests of cables. I learn a lot and understand many things ( of course not all ;-)).
Many thanks to Benjamin Lanz for great explanation.

O.K., now my Q.: what is possible ( may be average ) price of VLF HIPOT Tester in k$. I would like recommend to several companies bay one unit.
Best Regards.
Slava

 

[isquaredr]

Baur test equipment in Austria produce a portable unit called a freda, it has an rms output of 23kv

http://www2.baur.at/index.php?id=266&L=1.

Other manufacturers are HVinc in the states.
What is the system voltage?

 

[slavag]

Hi.
Our MV is up to 36kV.
Fault cases on 22kV cables.
Thanks.
Slava.

 

[isquaredr]

The uprated viola would test at twice phase voltage rms on a 35kv system

http://www2.baur.at/fileadmin/pdf/HSP/en_826-085_viola.pdf

I think anything larger would have to go vehicle mounted

 

[Zogzog]

Google VLF hopot, you will find several manufactures of these units. We use a hipotronics VLF with a tan daleta module, I think it is 50kV but I will have to check. About 10 grand if I recall.

 

[slavag]

Dear Zogzog.
Thanks a lot.
I found several mnf, but I don't try bay it.
I only would like know what is a possible price level.
Test of cables it's not my area.
BTW, I hear about some ultrasound PD test, what is it?
Regards.
Slava

 

[benlanz]

Slava,

You are welcome for the explanations. The ultrasound technique is typically an on-line technique. Ultrasound is only likely to detect PD activity when the probe is nearly in contact with the source. This creates a very high potential for false negatives and positives. Generally this technique is only useful for exposed cable components and can be expected to accurately detect < 3% of defects in cable systems

Benjamin Lanz
Vice Chair of IEEE 400
Sr. Application Engineer
IMCORP- Power Cable Reliability Consultants