9
Instruction Leaflet
I. L. 29-889B
Effective June 2011
Instructions for Digitrip RMS 910 Trip Unit
eaton corporation
www.eaton.com
Figure 7. Digitrip RMS 910 Type LSG.
Figure 8. Digitrip RMS 910 Type LSIG.
NOTICE
AFTER EACH TRIP OPERATION (WHETHER DUE TO OVERCURRENT
PROTECTION OR REMOTE CONTROL) THE AUTOMATIC LOCKOUT-AFTER-
TRIP FEATURE OF THE DIGITRIP RMS 910 TRIP UNIT MAINTAINS THE
CIRCUIT BREAKER IN A "TRIP-FREE" CONDITION, PROVIDED 120 VAC
CONTROL POWER REMAINS AVAILABLE TO THE POWER / RELAY MODULE.
THE TRIP UNIT MUST BE RESET BEFORE THE CIRCUIT BREAKER CAN BE
CLOSED AGAIN. THE RESET CAN BE ACCOMPLISHED EITHER LOCALLY BY
PRESSING AND RELEASING THE "TRIP RESET' PUSH BUTTON (SEE FIGURE
1),OR REMOTELY BY THE IMPACC SYSTEM (SEE SECTION 5.9).
After an over-current trip operation, the following information is
stored in the Trip Unit memory:
•
the cause of trip;
•
the values of currents at time of trip;
•
the time when the trip operation occurred; and
•
the total number of times the Trip Unit has tripped the breaker
electronically, (does not count shunt trip or manual operations) .
If the 120 Vac control power remains available to the Power / Relay
Module, this information can be viewed by INCOM
®
/ IMPACC
®
(See
Section 5 .6) . Therefore, Users may want to use an uninterruptible
power supply for the control power to the power relay module .
1.1.3 Discriminator (High Initial Current Release)
(For Types LS and LSG Trip Units Only)
When the Digitrip RMS 910 Trip Unit is not equipped with an
adjustable instantaneous protection setting, i .e . types LS or LSG, a
DlScriminator circuit (or high initial current release) is provided . The
non-adjustable release is pre-set at eleven (11) times the installed
rating plug current (I
n
) . The DlScriminator is enabled for approxi-
mately ten (10) cycles following the initial current flow through the
circuit breaker, provided the load current exceeds approximately 10%
of the circuit breaker frame (or current sensor) rating . Whenever
the load current falls below 10% the discriminator is rearmed . The
release, once rearmed will remain enabled until the load current
passing through the circuit breaker has exceeded the 10% value
for 10 cycles . Whenever the DlScriminator trips the circuit breaker,
the "OVERRIDE / DIS" LED will light "RED", and the Display will read
"DISC"
.
In the event the breaker is not intended to trip out on a circuit
whose current could initially be higher than 11 x I
n
, it is possible to
make the DlScriminator inactive .
If a circuit breaker would close onto a high short-circuit current,
when the DlScriminator is inactive, type
LS
or
LSG
Trip Units will
rely on the short-time delay function before tripping . If the fault
current exceeds the short-time withstand current capability of the
circuit breaker, the OverRlDe protection function will trip the breaker
without delay (see Section 1 .1 .4) . Also, please see Section 1 .1 .5 for
other exceptions when Zone lnterlocking is employed .
The DlScriminator (high initial current release) can be made inactive
by turning the "
OVERRIDE/
" setting switch (nearest the bottom edge
of the Trip Unit) from the "
DIS
" position, to the "[blank]" position (see
Figures 4 and 7) .
otee:
N
This switch has eight (8) positions, and seven (7) of the positions show
"DIS" in the window, ONLY ONE position shows "[blank]" .
otee:
N
When the "OVERRIDE/"window shows "[blank]", the only fast-acting
high short-circuit protection available is the OVERRIDE (Fixed
Instantaneous) (see Section 1 .1 .4 .) .
