VAMP 50 User Manual

Technical description 2 Protection functions 2.23 Inverse time operation
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103
Table 2.23.1-3 Constants for IEEE/ANSI inverse delay equation
Parameter
Delay type
A B C
LTI Long time inverse 0.086 0.185 0.02
LTVI Long time very inverse 28.55 0.712 2
LTEI
Long time extremely
inverse
64.07 0.250 2
MI Moderately inverse 0.0515 0.1140 0.02
VI Very inverse 19.61 0.491 2
EI Extremely inverse 28.2 0.1217 2
STI Short time inverse 0.16758 0.11858 0.02
STEI
Short time extremely
inverse
1.281 0.005 2
Example for Delay type "Moderately inverse (MI)":
k = 0.50
I = 4 pu
I
pickup
= 2 pu
A = 0.0515
B = 0.114
C = 0.02
9.11140.0
1
2
4
0515.0
50.0
02.0























t
The operation time in this example will be 1.9 seconds. The
same result can be read from Figure 2.23.1-8.
Figure 2.23.1-5 ANSI/IEEE long
time inverse delay
Figure 2.23.1-6 ANSI/IEEE long
time very inverse delay

VAMP 50 Specifications

General

Brand	VAMP
Model	50
Category	Relays
Language	English