GE relay 735 and IEEE Std C37.112-1996
GE relay 735 and IEEE Std C37.112-1996
(OP)
Hi
The GE relay 735/737 defines ANSI inverse curves using a different formula than the IEEE standard C37.112-1996 for overcurrent inverse-time characteristics.
Is this perhaps because the standard is newer than this relay?
Why do then GE call the curves with name "ANSI"? Does such pre 1996 ANSI/IEEE standard really exist?
Although the IEEE and GE formulae are different, the resulting curves do roughly match at small current ratios. At high currents the match is not good. Especially extremely inverse curves differ a lot.
Link to GE 735/737 manual:
http: //www.gein dustrial.c om/product s/manuals/ 735737/735 man-de.pdf
I would be grateful of any response.
The GE relay 735/737 defines ANSI inverse curves using a different formula than the IEEE standard C37.112-1996 for overcurrent inverse-time characteristics.
Is this perhaps because the standard is newer than this relay?
Why do then GE call the curves with name "ANSI"? Does such pre 1996 ANSI/IEEE standard really exist?
Although the IEEE and GE formulae are different, the resulting curves do roughly match at small current ratios. At high currents the match is not good. Especially extremely inverse curves differ a lot.
Link to GE 735/737 manual:
http:
I would be grateful of any response.






RE: GE relay 735 and IEEE Std C37.112-1996
RE: GE relay 735 and IEEE Std C37.112-1996
RE: GE relay 735 and IEEE Std C37.112-1996
On the other hand, the compliance with the standard by the manufacturer is optional. As far the curve resemble approximately and adjusted from moderately to extremely Inverse the manufacturer may be allow to called ANSI curve.
An interesting note how the equation provided by Multilin is related with the standard C37.112 is by observing the equation 1 of the enclose article.
http:
Notice that the terms an and bm are called coefficient of Sachdev model. Happens that Dr. M. S. Sachdev is an active member of the IEEE Standard C37.112
I hope this note could help to clarify some of your questions.