ABB Relion 670 series - Page 1193

[ ]
2
1
r
t
t s td
i
pickupn
= ×
-
æ ö
ç ÷
ç ÷
ç ÷
æ ö
ç ç ÷ ÷
è è ø ø
ANSIEQUATION1197 V1 EN (Equation 203)
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
204:
[ ]
r
pr
t
t s td
i
cr
pickupn
= ×
-
æ ö
ç ÷
ç ÷
ç ÷
æ ö
ç ç ÷ ÷
è è ø ø
ANSIEQUATION1198 V1 EN (Equation 204)
For RI and RD inverse time delay characteristics the possible delay time settings are
instantaneous and IEC constant time reset.
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
1MRK505222-UUS C Section 22
Inverse time characteristics
1187
Technical reference manual