where:
Un<
Set value for step 1 and step 2
U
Measured voltage
The type B curve is described as:
n
n
k
t
U
U
U
2.0
480
0.055
32
0.5
×
=
+
æ
ö
< -
×
-
ç
÷
<
è
ø
EQUATION1432 V2 EN
(Equation 107)
The customer programmable curve can be created as:
p
n
n
k A
t
D
U
U
B
C
U
é
ù
ê
ú
ê
ú
×
=
+
ê
ú
æ
ö
ê
ú
< -
×
-
ç
÷
ê
ú
<
è
ø
ë
û
EQUATION1433 V2 EN
(Equation 108)
When the denominator in the expression is equal to zero the time delay will be infinity.
There will be an undesired discontinuity. Therefore a tuning parameter
CrvSatn
is set
to compensate for this phenomenon. In the voltage interval
U
n
<
down to
U
n
<
· (1.0 –
CrvSatn/
100) the used voltage will be:
U
n
<
· (1.0 –
CrvSatn
/100). If the
programmable curve is used this parameter must be calculated so that:
0
100
CrvSatn
B
C
×
- >
EQUATION1435 V1 EN
(Equation 109)
The lowest voltage is always used for the inverse time delay integration. The details
of the different inverse time characteristics are shown in section
.
1MRK502052-UEN B
Section 9
Voltage protection
483
Technical manual
Summary of Contents for Relion REG670
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