29
Instruction Leaflet
I. L. 29-888B
Effective July 2011
Instructions for Digitrip RMS 810 Trip Unit
eaton corporation
www.eaton.com
appenDiX B: interpreting Display codes
after circuit Breaker trips
Given a 1600 A frame circuit breaker with an I
n
= 1000 A rating
plug installed.
CASE 1e: Overload Trip Operation and High Load Condition
Long Delay Current (Pick-up) Setting = 1 .0,
I
r
= 1000 A
Assume a prolonged 1500 A overload condition which results in an
automatic breaker trip operation . The following will occur:
•
The Long Delay Trip LED will turn "On" (see Figure 1) .
•
The coded message "LDT will appear in the Display Window (see
Figure 1) .
•
The Long Delay Relay in the Power / Relay Module (see Figures
2 and 10) will operate to close the remote Long Delay Trip Alarm
Contact .
Operator Actionse:
1 . Observe the mode of trip LED and coded message in the Display
Window .
2 . Press and release "STEP" push-button (see Figure 1) . This will
clear the coded cause of trip message in the Display Window .
3. View values of phase currents in Display Window (see
Figure 1), e.g.:
1.50 kA.
otee:
N
The phase current shown will be that identified by the "green" LED (see
Figure 1) that is turned "On", assume "
I
A
" . (It may not be the faulted phase .)
4 . Press and release the "STEP" push-button to view current values
similar to "I
A
", "I
B
", "I
C
", "I
G
" and "I
D
" . Each value of phase current
kA
appearing in the Display Window is the value at the time of
the trip operation .
5.
RECORD
all Values of interest; note which
"RED" LEDs
are light-
ed
BEFORE
resetting the Trip Unit .
6 . Reset the Trip Unit by pressing and releasing the "Trip Reset"
push-button (lower right corner of Trip Unit, see Figure 1) . All
coded messages and/or current values in the display window and
the cause of trip LED will turn "Off", and the Remote Alarm con-
tacts in the Power / Relay Module will be reset (open) .
NOTICE
FOLLOWING
LDT
TRIP OPERATIONS, IT IS ESSENTIAL THAT ANY CAUSE
OF OVERLOAD TRIP BE CORRECTED PRIOR TO RECLOSING THE CIRCUIT
BREAKER. SHOULD IT NOT BE CORRECTED AND THE CIRCUIT BREAKER BE
RE-CLOSED TOO QUICKLY, THEN BECAUSE OF THE INHERENT LONG TIME
MEMORY FUNCTION (SEE NOTE IN SECTION 3.3), THE LONG DELAY TRIP
ELEMENT WILL OPERATE FASTER THAN THE RELATED TIME-CURRENT
CURVE INDICATES.
THE AMOUNT OF TIME REQUIRED TO CLEAR THE LTM MEMORY CIRCUIT
IS A FUNCTION OF THE LONG DELAY TIME SETTING (SEE FIGURE 5). THE
LONGER THE DELAY SETTING, THE LONGER THE TIME REQUIRED TO
RESET THE MEMORY. TOTAL MEMORY CLEARING TIME COULD BE UP TO
TWELVE (12) MINUTES. THE LTM CAN BE RESET QUICKLY AS DESCRIBED IN
SECTION 4.4 (3).
The LTM memory function, simulates the conventional thermal type
(bi-metal) circuit breaker Trip Unit, and serves a useful function by
allowing the load conductors to cool down after an overload condition .
7 . After correcting the cause of the overload trip (LDT), allow for the
LTM memory circuit to reset and reclose the circuit breaker to
restore power to the load circuit .
otee:
N
As the current approached the overload condition, prior to the overload
trip operation, the following Trip Unit indications would have been visible .
•
The "HILD" message would begin to flash in the window when
the overload condition had exceeded 0 .85 x
I
r
for 40 seconds
or longer . To clear the "HILD" message and to view the present
magnitudes of the currents, press and release the (Black) "STEP"
push button on the display panel . Remember to push the "STEP"
button several times to be sure you see values of currents in all
phases, and ground/neutral as applicable .
•
The "High-Load" Relay in the Power / Relay Module (see Figures
2, 10, and Section 1 .4) would have been picked up (after a 40-sec-
ond delay), to close the remote High Load Alarm Contact . Press
and release the "TRIP RESET" push-button to reset the High Load
Relay Contact, or reset the Trip unit remotely by INCOM
®
(see
Section 5 .9) .
•
The Long Delay LED (Figure 1) begins to flash "On" and "Off" .
•
The message "LDPU" begins to flash in the display window when
the current value exceeds
I
r
.
CASE 2e: lnstantaneous Trip Operation
lnstantaneous Current (Pick-up) Setting = 8 x I
n
= 8000 A
Assume a 12 kA fault occurs .
Following the TRIP operation, the following will occur:
•
The lnstantaneous Trip LED will turn "On" (see Figure 1) .
•
The coded message "INST will appear in the Display Window (see
Figure 1) .
•
The Short-Circuit Relay in the Power / Relay Module (see Figures
2, 10, and Section 1 .4) will operate to close the Remote Short-
Circuit Trip Alarm contact .
Operator Actionse:
1 . Observe the mode of trip LED and the "INST" message in the
Display Window .
2. Press and release the "STEP" push-button to view current
values "I
A
", "I
B
", "I
C
", and "I
G
" or "I
D
" in the display window.
otee:
N
The phase current value displayed will be that identified by the "green"
LED (see Figure 1) that is turned "On" . (But, the first value you see may not
be for the faulted phase .) Each value of phase current appearing in the Display
Window, is the value at the time the trip operation was initiated .
3.
RECORD all Values
of interest; note which
"RED" LEDs
are
lighted
BEFORE
resetting the Trip Unit .
4 . The value of one phase current in display window (see Figure 1)
will have been the 12 .0 kA fault level .
otee:
N
Had the level of the fault current been more than 28 x
I
n
(or 28 kA in
this example) when the reason for trip message would be cleared (by push-
ing the "STEP" button), instead of the numerical value of current in kA, the
"ORNG" code is displayed to show the current level exceeded maximum
range of current sensor accuracy .
5 . After making sure you have a record of all pertinent information
stored in the Trip Unit memory, reset the Trip Unit by pressing
and releasing the "Trip Reset" push-button (lower right corner of
the Trip Unit, see Figure 1) . All coded messages, values of cur-
rent in the display window memory, and cause of trip LEDs will
turn "OFF", while the Remote Alarm Contacts of the signal relay
in the Power / Relay Module will reset (open) .
6 . Following any corrective actions and/or inspections of the circuit
breaker and related equipment, re-close the circuit breaker to
restore power to the load circuit .
