ABB REL300 Instruction Manual page 128

5.1.8 Timer Settings
a. Zone-2 timer (T2) setting should be coordinated with the Zone-1 and other high-speed trip
units on the adjacent line terminal. Coordination Time Interval (CTI) of 0.3 to 0.5 seconds
is recommended. For example, if T2 of 0.4 seconds is used, then the phase and ground
Zone-2 timers should be set as follows:
NOTE: T2P and T2G are separate timers; they can be set at different time settings.
b. Zone-3 timer (T3) settings would be similar to the above. For example, if T3 of 0.8 seconds
is required, then the phase and ground Zone-3 timer should be set as follows:
NOTE: T3P and T3G are separate timers; they can be set at a different time values.
c. For out-of-step block (OSB), if applied, the OSB override timer setting (OSOT) is deter-
mined by the power system operation. Its range is 400 to 4000 ms, in 16 ms steps. For
example, set REL300 OSOT = 500 if OSB override time of 500 ms is required.
d. For single-pole trip application only, the single phasing limit timer setting (62T) is for pre-
venting thermal damage to rotating machines, due to the I
phasing. Its range is 300 to 5000 ms. in 50 ms steps. The setting should be based on the
poorest (I
3PT is required before 1.55 seconds and after one pole has been open and the breaker
does not or cannot reclose.
e. For the blocking system only, the channel coordination timer setting (BLKT) is based on the
following application criteria:
BLKT > (Slowest remote carrier start time + channel time + margin) - (the fastest local 21P/
21NP pickup time)
Where channel time includes the transmitter and receiver times, and the times which occur
between these devices, e.g., wave propagation, interfacing relays, etc.
For REL300:
For example, the REL300 channel coordination timer should be determined as shown be-
low, if the channel time is 3 ms.
T2P = 0.4 and T2G = 0.4
T3P = 0.8 and T3G = 0.8
2
2 )
constant of the machines in service. For example, set REL300 62T = 1550, if
t
fastest 21P/21NP pickup time
slowest carrier start time
suggested margin time
BLKT = (4 + 3 + 2) - 14= -5
i.e., set BLKT= 0
component during single
2
= 14 ms
= 4 ms
= 2 ms
I.L. 40-385.7
5-7