Out Of Step Trip Override Timer (Osot); Remote Setting And Time Settings; Remote Setting (Setr); Time Settings (Time, Year, Month, Day, Wkday, Hour, Min) - ABB REL 356 Instruction Booklet

ABB REL 356 Current Differential Protection

Out of Step Trip Override Timer (OSOT)

This timer is started once an out of step condition is identified (output of OST1). A trip signal is generated if OSOT times
out and the apparent impedance seen by the relay is inside Zone 2 or Zone 3 reach and inside the RT blinder. The
recommended setting is 100 cycles.

Remote Setting and Time Settings

Remote Setting (SETR)

Set SETR = YES if remote setting via RCP is allowed.
Time Settings (TIME, YEAR, MONTH, DAY, WDAY, HOUR, MIN)
To set the clock in the relay, set TIME = YES and enter correct values as appropriate.

Setting Example - Tapped Load Application

Line and Transformer Data

Line data as for the general case:
CT ratio = 1200/5 = 240
VT ratio = 138000/115 = 1200
Z = 4.08 ohms, primary
ZT = 7% on a 20 MVA base
= ⋅
( ) ( )
ZT ohms ZT pu
3-34
Figure 3-3. Setting Example-Tapped Load Application
2 2
138
kV
= ⋅ =
. 0 07 66
MVA 20
. 65
OSOT = 100 cycles
SETR = YES
Settings and Application