[ ]
2
1
r
t
t s k
i
in
= ×
-
>
æ ö
ç ÷
ç ÷
ç ÷
æ ö
ç ÷ç ÷
è ø
è ø
EQUATION1197 V2 EN-US (Equation 100)
where:
The set value t
r
is the reset time in case of zero current after fault clearance.
The possibility of choice of reset characteristics is to some extent dependent of the
choice of time delay characteristic.
For the definite time delay characteristics the possible reset time settings are
instantaneous and IEC constant time reset.
For ANSI inverse time delay characteristics all three types of reset time
characteristics are available; instantaneous, IEC constant time reset and ANSI
current dependent reset time.
For IEC inverse time delay characteristics the possible delay time settings are
instantaneous and IEC set constant time reset).
For the programmable inverse time delay characteristics all three types of reset
time characteristics are available; instantaneous, IEC constant time reset and ANSI
current dependent reset time. If the current dependent type is used settings pr, tr
and cr must be given, see equation
101:
[ ]
r
pr
t
t s k
i
cr
in
= ×
-
>
æ ö
ç ÷
ç ÷
ç ÷
æ ö
ç ÷
ç ÷
è ø
è ø
EQUATION1198 V2 EN-US (Equation 101)
For RI and RD inverse time delay characteristics the possible delay time settings
are instantaneous and IEC constant time reset.
GUID-F7AA2194-4D1C-4475-8853-C7D064912614 v4
When inverse time overcurrent characteristic is selected, the
operate time of the stage will be the sum of the inverse time delay
and the set definite time delay. Thus, if only the inverse time delay
is required, it is important to set the definite time delay for that
stage to zero.
Section 25 1MRK 505 394-UEN A
Inverse time characteristics
876 Line differential protection RED650 2.2 IEC
Technical manual
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