ABB Relion 650 Series Technical Manual page 711

1MRK 511 424-UEN B
Bay control REC650 2.2 IEC
Technical manual
For inverse time characteristics a time will be initiated when the current reaches the
set start level. From the general expression of the characteristic the following can
be seen:
æ
p
æ ö
i
- × × -
( t B k ) ç
ç ÷
op è ø
>
in
è
EQUATION1190 V1 EN-US
where:
t is the operating time of the protection
op
The time elapsed to the moment of trip is reached when the integral fulfils
according to equation 41, in addition to the constant time delay:
æ ö
p
t
æ ö
i
ò
- × ³
ç C ÷ dt
ç ÷
è > ø
in
è ø
0
EQUATION1191 V1 EN-US
For the numerical protection the sum below must fulfil the equation for trip.
æ ö
p
æ ö
n i j ( )
å
D × -
t ç C ÷
ç ÷
è ø
>
in
è ø
=
j 1
EQUATION1192 V1 EN-US
where:
j = 1
Dt
n
i (j)
For inverse time operation, the inverse time characteristic is selectable. Both the
IEC and ANSI/IEEE standardized inverse time characteristics are supported.
For the IEC curves there is also a setting of the minimum time-lag of operation, see
figure 324.
Inverse time characteristics
ö
= ×
C ÷ A k
ø
×
A k
³ ×
A k
is the first protection execution cycle when a fault has been
detected, that is, when
i
>
1
>
in
EQUATION1193 V1 EN-US
is the time interval between two consecutive executions of the
protection algorithm,
is the number of the execution of the algorithm when the trip
time equation is fulfilled, that is, when a trip is given and
is the fault current at time j
Section 19
(Equation 40)
(Equation 41)
(Equation 42)
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