Inverse Characteristic; Ansi Inverse Time Characteristics - ABB RET670 Product Manual

Transformer protection RET670 2.0
Product version: 2.0

Inverse characteristic

Table 117. ANSI Inverse time characteristics
Function
Operating characteristic:
æ ö
A
ç ÷
= + × +
t B k tDef
( )
ç ÷
P
ç - ÷
I 1
è ø
EQUATION1249-SMALL V2 EN
Reset characteristic:
t r
= ×
t k
( )
2
-
I 1
EQUATION1250-SMALL V1 EN
I = I /I
measured set
ANSI Extremely Inverse
ANSI Very inverse
ANSI Normal Inverse
ANSI Moderately Inverse
ANSI Long Time Extremely Inverse
ANSI Long Time Very Inverse
ANSI Long Time Inverse
ABB
Range or value
k = (0.05-2.00) in steps of 0.01
A=28.2, B=0.1217, P=2.0 , tr=29.1
A=19.61, B=0.491, P=2.0 , tr=21.6
A=0.0086, B=0.0185, P=0.02, tr=0.46
A=0.0515, B=0.1140, P=0.02, tr=4.85
A=64.07, B=0.250, P=2.0, tr=30
A=28.55, B=0.712, P=2.0, tr=13.46
A=0.086, B=0.185, P=0.02, tr=4.6
1MRK 504 141-BEN C
Accuracy
ANSI/IEEE C37.112 ,
± 2.0% or ± 40 ms
whichever is greater
99