where:
Un> Set value for step 1 and step 2
U Measured voltage
The type B curve is described as:
2.0
480
0.035
32 0.5
n
n
k
t
UU
U
IECEQUATION2423 V2 EN-US (Equation 44)
The type C curve is described as:
3.0
480
0.035
32 0.5
n
n
k
t
U U
U
×
= +
æ ö
- >
× -
ç ÷
>
è ø
IECEQUATION2425 V1 EN-US (Equation 45)
The customer programmable curve is defined by the below equation, where A, B,
C, D, k and p are settings:
p
n
n
k A
t D
U U
B C
U
×
= +
æ ö
- >
× -
ç ÷
>
è ø
EQUATION1439 V2 EN-US
(Equation 46)
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 Un> up
to Un> · (1.0 + CrvSatn/100) the used voltage will be: Un> · (1.0 + CrvSatn/100).
If the programmable curve is used this parameter must be calculated so that:
EQUATION1435 V1 EN-US (Equation 47)
The highest phase (or phase-to-phase) voltage is always used for the inverse time
delay integration, see figure 112. The details of the different inverse time
characteristics are shown in section "Inverse characteristics".
1MRK 505 394-UEN A Section 9
Voltage protection
Line differential protection RED650 2.2 IEC 247
Technical manual
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