I.L. 40-385.5
13-5
to NO, unless it is needed. For example,
using MDAR (REL-300) as a non-pilot 3PT
backup with another system operated on
SPT mode, then set MDAR (REL-300) T1
to YES.
For example, Set MDAR (REL-300) T1 to
NO
(2) Zone-2 timer T2 setting should be coordi-
nated with the Zone-1 and other high
speed trip units on the adjacent line termi-
nal. 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 follow:
Set MDAR (REL-300) T2P = 0.40 and
T2G = 0.40
Note:
T2P and T2G are separate timers. They
can be set at a different time setting. Also,
either or both Zone-2 phase and ground
function(s) can be disabled by selecting
the Z2P and/or Z2G to OUT; or can be dis-
abled by selecting the T2P and/or T2G to
BLK.
(3) Zone-3 timer T3 settings would be similar
to the above. For example, if T3 of 0.8 sec-
onds is required, then the phase and
ground Zone-3 timer should be set as fol-
low:
Set MDAR (REL-300) T3P = 0.80 and
T3G = 0.80
Note:
T3P and T3G are separate timers. They
can be set at a different time setting. Also,
either or both Zone-3 phase and ground
function(s) can be disabled by selecting
the Z3P and/or Z3G to OUT; or can be dis-
abled by selecting the T3P and/or T3G to
BLK.
(4) For the blocking system only, the setting of
the channel coordination timer, BLKT, is
based on the application criteria
TC > (Slowest remote carrier start time +
channel time + margin) - (the fastest local
21P/21NP pickup time)
where channel time includes the transmit-
ter and receiver times and the times which
occur between these devices, e.g. wave
propagation, interfacing relays, etc.
For MDAR (REL-300), the fastest 21P/
21NP pickup time = 14 ms the slowest
carrier start time = 4 ms and suggested
margin time = 2 ms
For example, the MDAR (REL-300) chan-
nel coordination timer can be deter-
mined as below for a channel time of 3
ms.
T
c
= (4 + 3 + 2) - 14 = (-)
i.e., Set MDAR (REL-300) BLKT = 0
(5) For pilot systems, pilot ground trip is more
dependable on high Rf faults by applying
the FDOG/IoM/FDGT logic. Trip delay of
this supplemented function is controlled by
the FDGT timer setting. The range of this
timer is 0 to 15 cycles in 1 cycle steps and
with BLK step. Recommend to set this
timer longer than 3 cycles.
Set MDAR (REL-300) FDGT = 3
(6) For OSB (out-of-step block), if applied, the
OSTM timer setting is determined by the
power system operation practice. Its range
is 500 and 1000 ms.
For example, set MDAR (REL-300)
OSTM = 0500 if the poser system
requires 500 ms for the logic.
(7) For single-pole trip application only, the
single phasing limit timer setting, 62T, is
for preventing thermal damage to rotating
machines due to the I2 component during
single phasing. Its range is 300 to 5000
ms in 50 ms steps. The setting should be
based on the poorest (I2)2t constant of the
machines in service.
For example, Set MDAR (REL-300)
62T = 1.550, if 3PT is required before
1.55 seconds and after one pole has
been open and the breaker does not, or
cannot reclose.
13.2 Selections of MDAR (REL-300) settings
The following settings are determined by the applica-
tion. They do not require calculation.
(1) The OSC setting is for selecting the one of the
4 ways, TRIP/Z2TR/Z2Z3/
∆
I
∆
V, to initiate the
