High polarising index in repaired cable

[RAgrawal]

Hi, we have done straight through jont in a 33 kV UE 1c cable. After jointing, when we took the PI, PI is coming very high (more than 50 with 1 min & 10 min value as 5.98 and 342 M Ohm respectively). Can any one explain the phenomena pls?

 

[ScottyUK]

The IR values are so low that it's hardly worth doing a PI. An IR of only 6M[Ω] suggests the cable has a fairly serious problem, especially as the PI test is usually done at a voltage well below the cable's service voltage. Is this a very long cable with large capacitance, and perhaps a marginally capable Megger?

 

[RAgrawal]

Sorry, IR values are in G Ohm.

 

[ViCH]

If its in GOhm, then no need to worry. PI test actually required for windings insulation, and if your 1minute IR shows good result, PI is not recommended.
Btw, what is the cable wire size and length. What voltage did You inject during IR/PI ?