IEC 60255-151:2009 / IEEE C37.112-2018

Table 1 / IEEE C37.112 Table 1

IDMT overcurrent curve constants

The IDMT tool reads the three constants that shape each named relay curve.

Verified: read against the printed standard, pages 29 (PDF 31), Annex A Table A.1. Checked 26 Sept 2026.

Units: K -, Alpha -, C -

These are the values AmpSize encodes. No text of the standard is reproduced. Verify against the current standard.

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7 rows

Table 1 / IEEE C37.112 Table 1, IDMT overcurrent curve constants
Name	K (-)	Alpha (-)	C (-)
IEC-SI	0.14	0.02	0
IEC-VI	13.5	1	0
IEC-EI	80	2	0
IEC-LTI	120	1	0
IEEE-MI	0.0515	0.02	0.114
IEEE-VI	19.61	2	0.491
IEEE-EI	28.2	2	0.1217

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