20.3 Inverse characteristics
IP15797-1 v2
M12388-1 v21
Table 585: ANSI Inverse time characteristics
Function
Range or value Accuracy
Operating characteristic:
( )
1
P
A
t B k tDef
I
æ ö
ç ÷
= + × +
ç ÷
ç - ÷
è ø
EQUATION1249-SMALL V2 EN-US
Reset characteristic:
EQUATION1250-SMALL V1 EN-US
I = I
measured
/I
set
0.10 ≤ k ≤ 3.00
1.5 x I
set
≤ I ≤ 20 x I
set
ANSI/IEEE C37.112 ,
±2.0% or ±40 ms
whichever is greater
ANSI Extremely Inverse A=28.2, B=0.1217, P=2.0 ,
tr=29.1
ANSI Very inverse A=19.61, B=0.491, P=2.0 ,
tr=21.6
ANSI Normal Inverse A=0.0086, B=0.0185, P=0.02,
tr=0.46
ANSI Moderately Inverse A=0.0515, B=0.1140, P=0.02,
tr=4.85
ANSI Long Time Extremely Inverse A=64.07, B=0.250, P=2.0,
tr=30
ANSI Long Time Very Inverse A=28.55, B=0.712, P=2.0,
tr=13.46
ANSI Long Time Inverse A=0.086, B=0.185, P=0.02,
tr=4.6
1MRK 505 384-UEN A Section 20
Inverse time characteristics
Breaker protection REQ650 2.2 IEC 741
Technical manual
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