Insulation Resistance for Underground Cables

You can buy IEEE Codes

But this is free without violating the copyright act.

Refer page 37 and page 40 onwards for your type of cable.

In fact I will recommend you to go through the whole. This one is supposed to be a standard reference book, like a few others from Megger.

Dear Guest

Nice and Good refrence link.

Thanks so much

I need some free links regarding study of protective relays their operation/maintenace and setting testing methods/applications.

Also some regading PLC study for beginners and to advance to one more step ahead.

Please also mail your personal mail i.d

mine is vijay@uflexltd.com

cell +91-9906900200

Thanks again

VSH

If you are from India, please refer to the IE Rules (Rule No. 48) and IS 732. These rules specify the minimum insulation values.

Dear friends, As suggested by some of our guests,I went through some documents.The thumb rule says the min. IR value should be the operating voltage in Kv plus 1 viz-if 433volt then it will be 0.433+ 1=1.433MOhm.Likely,if it is 11Kv then 11+1=12MOhm and so on.IER 1956 cl-46 says the min.IR value should be as defined in IS 1989(732).I couldn't find that however, some where it was found for low and medium voltage the min.acceptable value is 1MOhm and for HT 5Mohm.Apart from that,cable manufacturers show it as 500MOhm.For old cables,some where 100MOhm has been considered as safe value.Under these variable submissions,I am not assured what should exactly be the safest IR value for one of my XLPE around 15 year old 11Kv cable to charge my 750kVA 11/0.4kV xfr.When tested by one 5000v megger,it shows19MOhm between leads and 15MOhm between lead(s) to Earth.After all the cable was lying idle(disconnected) for last one year.In my opinion,the thumb rule as mentioned above may be the safest value for machineries,transformers and limited to an assumed value relevant to a voltage between ph to earth(body) which is root 3 times less than the line voltage.In my case leakage current has no relevance as the control ckt is out of order and non-functional.Learned guests and friends may interact on this specific issue and advice/suggest what to do.I don't dare to charge as there is no control even no drop out fuse provisions on the structure.If my above concept is wrong,then be corrected pl.Thanks. nayakair