Silly question about standard dielectric absorption ratio

[akyip]

Hey guys,

I have a silly question about dielectric absorption ratio.

Many times I have seen that the standard dielectric absorption ratio R 60 sec / R 30 sec judges insulation condition as follows:

DAR < 1: Bad or dangerous insulation

1 =< DAR < 1.25: Questionable insulation

1.25 =< DAR < 1.4: Good Insulation

DAR >= 1.6: Excellent insulation

My question is, what about values of DAR ranging inclusively from 1.4 to less than 1.6? Do those fall under good insulation?

 

[PEExam123]

For Dielectric Absorption Ratio : 60/30 Second : 1-1.25 (Questionable), 1.4 - 1.6 (Good), >1.6 (Excellent)

Some also use..


1.4 or more (Excellent), 


1.25 - 1.0 (Good),


1.0 or less (bad) 

 

[DarkLegion PE]

Like PEExam123 said, I'd assume they're good. Not sure if we'd get that on the actual test though since the handbook doesnt give us those ranges. hmm 

 

[akyip]

For Dielectric Absorption Ratio : 60/30 Second : 1-1.25 (Questionable), 1.4 - 1.6 (Good), >1.6 (Excellent)

Some also use..


1.4 or more (Excellent), 


1.25 - 1.0 (Good),


1.0 or less (bad) 

Hm, so here what about the valued between 1.25 and 1.4? Do these values count as only good insulation?

 

[Byk]

Hm, so here what about the valued between 1.25 and 1.4? Do these values count as only good insulation?

In real life, at that point I would go for 10 min. reading which will give us polarization index.

If I recall correctly from a top of my head for PI: Reading of less than 1 will be consider dangerous; 1 to 2 will be questionable, 2 to 4 - good and above 4 excellent.

Here is a good guide by megger that I refer to alot https://www.instrumart.com/assets/Megger-Guide-to-Insulation-Testing.pdf

 

[RedRaider2020]

From what I've seen if it's over 1 the equipment is put back in service assuming there hasn't been a decrease over time. (if historical records are properly maintained and checked) There a lot of different policies on this though depending on where you work. I've never heard anyone debate over whether the readings were very good vs excellent. When the debate takes place it's usually about if it's good or bad.