Birch
Electrical
- Jan 5, 2001
- 3
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 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, if the GE time dial values are multiplied by five. At high currents the match is not good. Especially extremely inverse curves differ a lot.
Link to GE 735/737 manual:
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 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, if the GE time dial values are multiplied by five. At high currents the match is not good. Especially extremely inverse curves differ a lot.
Link to GE 735/737 manual:
I would be grateful of any response.