Override (Fixed Instantaneous); Zone Interlocking; Protection Settings; General - Eaton Digitrip RMS 510 LI Instruction Manual

Page 6
Notes:
1 This switch has eight (8) positions, and seven (7)
of them show
"DIS"
ONE position shows "[BLANK]".
2 When the
"OVERRIDEI"
"[BLANK]", the only fast-acting high short-circuit
protection available is the OVERRIDE [Fixed
Instantaneous]. (See 3.5 below.)

3.5 OVERRIDE (Fixed Instantaneous)

(For Types LS And LSG Trip Units Only)
When the Digitrip RMS 510 Trip Unit is not equipped with
an adjustable instantaneous setting, i.e., types LS or
LSG, the Fixed Instantaneous "Override" analog trip cir­
cuit is automatically pre-set to a value no greater than the
short-time withstand current rating of the circuit breaker
in which the trip unit is installed. Since the specific values
vary for different circuit breaker types and ratings, refer to
time-current curves, listed in Section 9, for the values
applicable to your breaker. If breaker trips due to high
instantaneous current, the "OVERRIDE" LED will light
"RED".

3.6 Zone Interlocking

Zone Selective Interlocking (or Zone Interlocking) is
available (see Fig. 3) for Digitrip RMS Trip Units having
Short Delay and/or Ground Fault protection. Zone Selec­
tive Interlocking provides the fastest possible tripping for
faults within the breaker's zone of protection, and yet also
provides positive coordination among all breakers in the
system (mains, ties, feeders and downstream breakers)
to limit the outage to the affected part of the system only.
When Zone Interlocking is enabled, a fault within the
breaker's zone of protection will cause the RMS DIG­
ITRIP trip unit to:
a) Trip the affected breaker instantaneously,
and at the same time
b) Send a signal to upstream RMS DIGITRIP
trip units to restrain from tripping immedi­
ately. The restraining signal causes the
upstream breakers to follow their set coor­
dination times, so that only the minimum
service is disrupted, while the fault is
cleared in the shortest time possible.
(This signal requires only a single pair of wires from the
output terminals of the downstream breaker's trip unit to
the input terminals of the upstream breaker's trip unit. For
specific instructions see the applicable connection dia­
grams for your breaker listed in Section 9.0.)
in the window, while ONLY
window shows
Note: If a breaker (M) receives a Zone Interlocking
signal from another breaker (F), but the fault current
level is less than the trip unit setting for breaker (M),
the signal from the other breaker (F) will not cause
breaker (M) to trip.
A
CAUTION
IF ZONE INTERLOCKING IS NOT TO BE USED (I.E.
STANDARD TIME-DELAY COORDINATION ONLY IS
INTENDED), THE ZONE INTERLOCKING TERMINALS
MUST BE CONNECTED WITH JUMPER WIRES, AS
SPECIFIED ON THE CONNECTION DIAGRAMS FOR
YOUR BREAKER (SEE SECTION 9.0), SO THE TIME­
DELAY SETTINGS WILL PROVIDE THE INTENDED
COORDINATION.
For an example of how Zone Selective Interlocking may
be used, See Appendix A.

4.0 PROTECTION SETTINGS

4.1 General

Prior to placing circuit breaker in operation, each trip unit
protection setting must be set to the values specified by
the engineer responsible for the installation. The number
of settings that must be made is determined by the pro­
tector model supplied as illustrated in Figs. 2.1 through
2.6. Each setting is made with a rotary switch, using a
small screwdriver. The selected setting for each adjust­
ment appears in its respective rectangular viewing win­
dow as illustrated in Fig. 1.
The installed rating plug establishes the maximum con­
tinuous current rating of the circuit breaker (In). Instanta­
neous and ground current settings are defined in
multiples of (In).
To illustrate the effect of each protection curve setting,
simulated Time-Current curves are pictured on the face
of the trip unit. The rotary switch to make each setting is
located nearest that portion of the simulated Time-Cur­
rent curve it controls. Should an automatic "trip" occur (as
a result of the current exceeding the pre-selected value),
the LED in the appropriate segment of the simulated
Time-Current curve will light "RED" indicating the reason
for "trip".
The available settings, along with the illustrated effect of
changing the settings, are given in Figs. 4.1 through 4.7.
I.L. 29-8858
Effective May 1997