ABB Relion 670 Series Technical Reference Manual page 246

Section 7
Voltage protection
240
k
=
t
- >
æ ö
U U
ç ÷
>
è U ø
IEC09000051 V1 EN
The type B curve is described as:
×
k 480
=
t
æ - > ö
U U
ç × - ÷
32 0.5
è ø
>
U
IECEQUATION2287 V1 EN
The type C curve is described as:
×
k 480
=
t
æ - > ö
U U
ç × - ÷
32 0.5
è ø
>
U
IECEQUATION2288 V1 EN
The customer programmable curve can be created as:
×
k A
=
t
- >
æ ö
U U
× -
B C
ç ÷
>
è U ø
EQUATION1439 V1 EN
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> up to
U> · (1.0 + CrvSatn/100) the used voltage will be: U> · (1.0 + CrvSatn/100). If the
programmable curve is used this parameter must be calculated so that:
CrvSatn
× - >
B C 0
100
EQUATION1440 V1 EN
The details of the different inverse time characteristics are shown in section
"Inverse characteristics".
TRIP signal issuing requires that the residual overvoltage condition continues for at
least the user set time delay. This time delay is set by the parameter t1 and t2 for
definite time mode (DT) and by some special voltage level dependent time curves
for the inverse time mode (IDMT).
-
0.035
2.0
+
0.035
3.0
+
D
p
1MRK 505 208-UEN B
(Equation 56)
(Equation 57)
(Equation 58)
(Equation 59)
(Equation 60)
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