DC Absorption Test
DC Absorption Test
(OP)
Does anyone have experience in performing the DC Absorption Test & its analysis?
I know it involves applying 2.5/5 KV DC to the winding insulation & recording the charging current for a set period (typically 1000 seconds) & then discharging through an external resistor for the same period, again recording the same. These are then plotted on log scales as a function of time.
I believe it is possible to calculate various time constants (ion migration, slow relaxation, interfacial polarization) from these, but I do not know how (& the basis for analyzing this data). Any information would be very helpful.
Regards,
Aditya
I know it involves applying 2.5/5 KV DC to the winding insulation & recording the charging current for a set period (typically 1000 seconds) & then discharging through an external resistor for the same period, again recording the same. These are then plotted on log scales as a function of time.
I believe it is possible to calculate various time constants (ion migration, slow relaxation, interfacial polarization) from these, but I do not know how (& the basis for analyzing this data). Any information would be very helpful.
Regards,
Aditya





RE: DC Absorption Test
What are you trying to acomplish? What are you testing?
RE: DC Absorption Test
Consider IEEE Std 43-2000.
Absorption Current(IA), per IEEE Std 43 "is the current resulting from molecular polarizing and electron drift, wich decays with time of voltage application at a decreasing rate from a comparatively high initial value to nearly zero , and depends on the type and condition of the bonding material used in the insulation system."
It is a straight line in a log-log current-time graph.
IA= Kt^(-n)
were:
K is a function of the particular insulation system and applied voltage.
t is the time of applied direct voltage.
n is a function of the particular insulation system.
RE: DC Absorption Test
Our company recently performed a no. of tests (tan delta, PD, RSO, DC hi-pot, etc. on a 30 year 200 MW generator while overhauling it. The client has now pulled out an old report done by TVA, USA where this test has been performed, along with non-linear analysis of insulation (never heard of that either). They are insisting that we perform the identical tests so as to get a comparison.
I've done both the tests but interpretation is a question. I've shown them IEEE 43, not interested. Seems TVA are experts in Residual Life Analysis & we have to copy them.
Lets see how things work out. I got a good paper through Electricpete's reference, will go through it & see.
Regards,
Aditya
RE: DC Absorption Test
Could you pls mail me the paper on this ?
Thanks