15
Instruction Leaflet
I. L. 29-889B
Effective June 2011
Instructions for Digitrip RMS 910 Trip Unit
eaton corporation
www.eaton.com
Following a circuit breaker TRIP operation, the display window
indicates the reason for trip, using coded messages such as, INST
(Instantaneous Trip), LDT (Long Delay Trip) etc . As with the ALARM
function, press and release the "STEP" push-button to delete the
reason for trip message and the display window will then show the
values of current at the time of trip (see Notes (1), (2), and (3) under
Table 3) . The values remain in memory, and the "red" reason for Trip
LED (see Figures 1 and 3 through 8) remains lighted, until the Trip
Unit is reset by pressing and releasing the "TRIP RESET push-button
in the lower right corner of the Trip Unit (see Figure 1) .
otee:
N
After a trip condition, RECORD all Values of interest and note which
"RED" LEDs are lighted . Correct the cause of the overload or fault BEFORE
YOU RESET the Trip Unit to avoid repeated tripping .
The LOCKOUT after trip feature requires the Trip Unit to be reset
before the breaker can be closed again .
For examples of how to interpret the display after an overload and
after a short-circuit, see Appendix B .
Figure 12. Auxiliary Power Module.
1.2.1.1 ROM Error ... See I.L.
If the message, "ROM Error . . . See I .L .", scrolls across the display
window, it means that a non-fatal error has been detected some-
where in the Trip Unit's non-volatile memory . The Trip Unit will still
function to protect the circuit, but the calibration may be degraded
by a few percent . The scrolling message will not remain in the win-
dow constantly but is repeated periodically to remind you to replace
the Trip Unit .
1.3 Frame Rating, Sensor Rating (Where Applicable) and
Rating Plugs
The
Frame Rating
of a circuit breaker is the maximum RMS cur-
rent it can carry continuously . The maximum Short-Circuit Current
Ratings of the circuit breaker are usually related to the Frame Rating
as well .
It is often times desirable to be able to choose a current value
(I
n
)
,
less than the full frame rating, to be the basis for the circuit break-
er's protection functions, without affecting its short-circuit current
capability . For the Digitrip RMS 910 Trip Unit the maximum continu-
ous current (I
n
) is set by the
Rating Plug
(and/or
Current Sensors
,
where applicable) - see Section 6 for specific instructions for your
circuit breaker type .
The
(Current) Sensor Rating
(where applicable) is the maximum
RMS current the circuit breaker can carry with the specified current
sensors installed . The Sensor Rating can be the same or less than
the Frame Rating, but not greater .
The
Rating Plug
(see Figure 9) fits into a special cavity to complete
the Trip Unit (see Figure 1) .
CAUTION
BEFORE YOU FIT THE RATING PLUG INTO THE TRIP UNIT, BE SURE TO CHECK THAT
THE BREAKER TYPE AND FRAME RATING (OR SENSOR RATING IF APPLICABLE),
MATCH THOSE PRINTED ON THE RATING PLUG COVER. INSTALLING A RATING PLUG
THAT DOES NOT MATCH THE BREAKER TYPE AND FRAME RATING (OR SENSOR
RATING, IF APPLICABLE), CAN PRODUCE SERIOUS MIS-COORDINATION AND/OR
FAILURE OF THE PROTECTION SYSTEM.
After installing the Rating Plug, press and release the "TRIP RESET"
push-button to turn off any illuminated LEDs . The purpose of the
rating plug is to set the value of I
n
, the basis for the Trip Unit protec-
tion function current settings (see Section 3 for details) . Each circuit
breaker frame rating represents the maximum current it can carry
continuously . However for proper coordination of over-current pro-
tection, it is often desirable to choose different levels of I
n
for differ-
ent circuit breakers of the same frame rating . An assortment of rat-
ing plugs with different I
n
values is available for each breaker frame
rating (see circuit breaker instruction leaflet supplements listed in
Section 6) to give the user flexibility to change the value of I
n
with-
out having to change the primary current sensors on the breaker .
By changing the rating plug, the User can easily change the range
of current protection settings without having to remove the circuit
breaker from its enclosure .
For example, if one expects a circuit to carry 600 A initially, but
then increase to 1400 A in the future, one could initially install 1600
A cables and a 1600 A breaker frame with the Trip Unit rating plug
whose I
n
= 800 A . Then later on when the additional load is ready
to come on line, the rating plug could be exchanged for one with I
n
= 1600 A, without having to remove the breaker from its enclosure .
The available settings would give the following choices:
Long Delay Setting
I
r
= I
n
x: .5 .6 .7 .8 .85 .9 .95 1 .0
Plug I
n
=800 A
LDPU I
r
= : 400 480 560 640 680 720 760 800 A
Plug I
n
= 1600 A
LDPU I
r
= : 800 960 1120 1280 1360 1440 1520 1600 A
otee:
N
Rating plugs from Digitrip models 500 / 600 / 700 / 800 CANNOT be
used with model 910 Trip Units . The connection pins are located in different
positions, so one cannot accidentally use the incorrect type of plug .
Rating Plugs for the Digitrip RMS 910 Trip Units are marked for, and
may be applied on both 50 and 60 Hz systems .
Rating plugs have two current ratings listed on their covers (see
Figure 9) .
•
The "Must Use With Frame Rated" current value (or "Sensor
Rated", if applicable),
and
•
" I
n
(rated I)=" current value .
This latter value (I
n
) is the basis for the Trip Unit current settings:
•
The instantaneous and Ground Current Settings (if applicable) are
multiples of (I
n
) (see Sections 3 .6 and 3 .8 .) .
•
The Long Delay Current Setting,
I
r
is a multiple of (I
n
) . Long
Delay Current Setting =
I
r
= LD x (I
n
) (see Section 3 .2 .) .
•
The Short Delay Current Setting (if provided) is a multiple of
I
r
which in turn is a multiple of (I
n
) . Short Delay Current Setting =
SD x
I
r
= SD x LD x (I
n
) (see Section 3 .4) .
If the rating plug is missing or not well connected, then the display
will show "PLUG" and the instantaneous / override LED will be
lighted . If the circuit breaker is closed, it will trip; if it is open, it will
remain trip-free, as long as 120 Vac control power is available to the
Power / Relay Module .
Even if control power is lost, and the rating plug condition is not cor-
rected, as soon as the three-phase current through the circuit break-
er reaches 20% (40% if single-phase current) of the frame / current
Plug for 120Vac
Receptacle
Trip Unit Connector (Fits into Keyed
Cavity in Top Right Corner of Trip
Unit . See Figure 1)
