Effective 8/2006
Page 16
I.L. 66A7534H04
Figure 4.6 Instantaneous Current Settings
4.7 Ground Fault Current Setting
The eight “Ground Fault Current Settings” are labeled with
values from .25 to .75 x (
I
n) and the other one is OFF.
(See Figure 4.7)
. The specific “Ground Current Settings” for
each model are listed in Figure 4.7 and on the applicable
time-current curve for the circuit breaker.
Figure 4.7 Ground Fault Current Settings
4.8 Ground Fault Time Delay Setting
As illustrated in Figure 4.8, there are two different Ground
Fault curve shapes: fixed time (FLAT) or I
2
t response. The
shape selected depends on the type of selective coordina-
tion chosen. The I
2
t response will provide a longer time
delay for current below 0.625 x
I
n than will the FLAT
response.
Five FLAT (.1, .2, .3, .4, .5 seconds) and three I
2
t (.1*, .3*,
.5* seconds) response time delay settings are available.
The I
2
t response settings are identified by an asterisk (*).
The I
2
t response is applicable to currents less than 0.625
times the ampere rating of the installed rating plug (
I
n). For
currents greater than 0.625 x
I
n
the
I
2
t response reverts to
the FLAT response.
NOTE:
Also see Section 3.3 - Zone Interlocking.
M1 value is specified on rating plug.
Setting Inst.
x n
I
6
Available Settings
2, 3, 4, 6, 8,
10, M1, OFF
In Multiples of
Rating Plug
Amperes ( n)
I
Available Settings
0.25, .3, .35, .4,
.5, .6, .75, OFF
Gnd-Fault
Setting
x n
I
.4
Figure 4.8 Ground Fault Time Delay Settings
4.9 INCOM (Digitrip 520MCV Models only)
INCOM communication to a host computer or a BIM is
possible with the Digitrip 520MCV unit. The address range
is 001 through 999. The factory default address is 999 hex.
To set the desired address or to view the address, depress
and hold the RESET/BATTERY TEST button for five
seconds. Depress the STEP button to select a new
address. Users may simultaneously depress and hold in
the STEP and RESET/BATTERY TEST buttons for fast
advance.
4.9.1 Breaker Interface Module (BIM)
The Breaker Interface Module (BIM) can be used to
monitor up to 31 Digitrip 520MCV trip units. The accept-
able addresses are 001 through 031.
4.9.2 Remote Master Computer
When desired, Digitrip 520MCV Trip Units can communi-
cate with a BIM or remote master computer (IBM PC
compatible with Cutler Hammer Inc. CONI card or MINT )
and using PowerNet communication software version 3.20
or greater.
(See Figure 4.9 for typical wiring.)
