VAMP 50 User Manual

Technical description 2 Protection functions 2.23 Inverse time operation
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Example 1 of limitation
CT = 750/5
Application mode is Feeder (selection is available only in
VAMP52)
CT
0
= 100/1 (cable CT is used for residual current)
The CT
0
is connected to a 1 A terminals of input I
01
.
For overcurrent stage I> the table above gives 12.5 A. Thus the
maximum setting for I> stage giving full inverse delay range is
12.5 A / 5 A = 2.5 xI
N
= 1875 A
Primary
.
For earth fault stage I
0
> the table above gives 0.5 A. Thus the
maximum setting for I
0
> stage giving full inverse delay range is
0.5 A / 1 A = 0.5 xI
0N
= 50 A
Primary
.
Example 2 of limitation
CT = 750/5
Application mode is Motor (selection is available only in
VAMP52)
Rated current of the motor = 600 A
I
0Calc
(= I
L1
+I
L2
+I
L3
) is used for residual current
At secondary level the rated motor current is 600/750*5 = 4 A
For overcurrent stage I> the table above gives 12.5 A. Thus the
maximum setting giving full inverse delay range is 12.5 A / 4 A
= 3.13 xI
MOT
= 1875 A
Primary
.
For earth fault stage I
0
> the table above gives 12.5 A. Thus the
maximum setting for I
0
> stage giving full inverse delay range is
12.5 A / 5 A = 2.5 xI
0N
= 1875 A
Primary
.
2.23.1. Standard inverse delays IEC, IEEE, IEEE2, RI
The available standard inverse delays are divided in four
categories IEC, IEEE, IEEE2 and RI called delay curve
families. Each category of family contains a set of different
delay types according the following table.
Inverse time setting error signal
The inverse time setting error signal will be activated, if the
delay category is cha
nged and the old delay type doesn't exist
in the new category. See chapter 2.23 for more details.

VAMP 50 Specifications

General

Brand	VAMP
Model	50
Category	Relays
Language	English