Radio-influence voltage

[iskar2000]

Hi!
I have find old NEMA standard (1970) :

System voltage RIV level
23.0-34.5 650
46.0-69.0 1250
115.0-138.0 2500
161.0-345.0 5000
but I thing this level now are 10 time lower. Can some body give me right levels actual now?

 

[prc]

NEMA TR-1 1980 edition retains the same RIV levels for different Voltage ratings. Find no reason to think that NEMA might have reduced these levels in its latest edition.
However if you are looking for PD levels it is quite low -only 100 micro volts during 1 hour test as per 1999 edition of ANSI C57 -12.90 standard ,irrespective of voltage levels

 

[stevenal]

'93 version only gives a performance level for distribution transformers of 69kV and less. That limit is 100 uV or less.

 

[prc]

I believe '93version also gives values same as earlier editions .There are two RIV values involved:
One external RIV values for the terminal conneting part,values varying with the voltage class,measured at 1.0 or 1.3 pu voltage
Second for the internal corona in paper insulation ,which is specified as 100 uV or less,measured at 1.3 or 1.5 pu voltage.

 

[stevenal]

prc,
Perhaps you could tell me where to look. RIV is addressed on page 2, sec. 0.03. 0.03.1 deals with RIV of distribution transformers. Next paragragh is 0.04 dealing with power factor. Part 1 deals with power transformers, but simply references ANSI C57.12.10 and C57.92.??

 

[prc]

stevenal,
I am sorry I dont have NEMA 93 edition!
From what you mentioned it looks like for Power Trfs NEMA is asking us to refer to ANSI std.In ANSI C57.12.90,RIV is specified only for internal PD ie100uV irrespective of voltage class and there is no mention of external PD limits.Any way this external PD limit was there only in NEMA std.