Per IEEE 43 - 2013 Part 12.2.2, when IR value exceeds 5 Gohms @ 1 min, PI test can have inconclusive results, and may not be a valid indication of the insulation condition. Means the calculated PI may not be meaningful. Megger may be a giant, but they won't reveal the point for their benefit. Most of their literature is based on obsolete insulating materials purposely. Something like outdated syllabus. Then what's the working voltage of that jumper? How you selected 5 KV as injected voltage? Thanks.
When referring to molecules, I believe you mean atoms. Those atoms containing a balance of the nucleus of protons surrounded by the orbiting electron field - the excited (free) electrons being those which move from atom to atom - hence voltage potential and current flow.
In the PI art, the molecules are referring to insulator molecules - usually plastics. I would agree with you for conductors. Then again, if we are getting these minuscule current flows from plastics, I suppose we are stripping the outer electrons from the outer orbitals of the molecules with the high voltages.
why you not measure betwen conductors instead,?, the way you’re testing will show insulation results only at tha point, but i you check the cord betwen conductors will give de idea how is the insulation alongside, thanks
The tested system acts like a capacitor. The theory of a capacitor in a DC system is that during its initial stages, there are some current transfer between the two conductors. After some time, it tapers off and no current transfer occurs as it is an open circuit. So for a PI test, the first minute is like the initial stages where there are some small current transfer, hence the lower resistance due to ohms law. Around the 10 minute mark should be the point where there's no current transfer, hence the higher resistance due to ohms law.
Excellent explanation, thank you so much!
Is the polarization index table listed here in the NEC or where is that general info found
Per IEEE 43 - 2013 Part 12.2.2, when IR value exceeds 5 Gohms @ 1 min, PI test can have inconclusive results, and may not be a valid indication of the insulation condition. Means the calculated PI may not be meaningful.
Megger may be a giant, but they won't reveal the point for their benefit. Most of their literature is based on obsolete insulating materials purposely. Something like outdated syllabus.
Then what's the working voltage of that jumper? How you selected 5 KV as injected voltage?
Thanks.
Nice explanation, thanks a lot sir 👏🏼
When referring to molecules, I believe you mean atoms. Those atoms containing a balance of the nucleus of protons surrounded by the orbiting electron field - the excited (free) electrons being those which move from atom to atom - hence voltage potential and current flow.
In the PI art, the molecules are referring to insulator molecules - usually plastics. I would agree with you for conductors. Then again, if we are getting these minuscule current flows from plastics, I suppose we are stripping the outer electrons from the outer orbitals of the molecules with the high voltages.
so easy to understand... thanks sir
why you not measure betwen conductors instead,?, the way you’re testing will show insulation results only at tha point, but i you check the cord betwen conductors will give de idea how is the insulation alongside, thanks
great
GREAT !!!
the question is, why does resistance increase with time?
The tested system acts like a capacitor. The theory of a capacitor in a DC system is that during its initial stages, there are some current transfer between the two conductors. After some time, it tapers off and no current transfer occurs as it is an open circuit.
So for a PI test, the first minute is like the initial stages where there are some small current transfer, hence the lower resistance due to ohms law. Around the 10 minute mark should be the point where there's no current transfer, hence the higher resistance due to ohms law.
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Why are we taking 10 min??
It is an industry standard test. PI is a 10 minute test.
Hi sir... which standard it is mentioned?
@@nahashamsa2791 IEEE Standard 43-2000
@@OmniBaddie Please read part 12.2.2. PI is not recommended if the 1 min IR value exceeds 5 Gohms.