Eaton Cutler-Hammer Digitrip RMS 510 - Page 18

AD 33-855-4
Page
17
3.5
Long
Time Memory
Function
ln addition
to the standard Long
Delay Protection
Element,
Digikip RMS 510,
610, 810, &
910 Trip
Units also
have
an
unpowered Long
Time
Memory
function
(LTM),
which serves
to
protect
load cir-
cuits from
the effects of repeated
overload condi-
tions. lf a Breaker
is reclosed soon
after a Long
Delay Trip and
the current again
exceeds
the Long
Delay Setting
(lr),
the LTM
automatically
reduces
the
time to trip to allow
for the fact
that the
Load
Circuit
temperature is already
higher than
normal,
due
to the
prior
overload condition.
Each time an
overload condition
is repeated,
the LTM causes
the
Breaker
to trip in a
time
progressively
earlier
than
the
"Long Delay Time Settings".
When the
Load
Current
returns to normal,
the LTM begins
to reset;
and
after about
10 minutes it
has reset fully.
There-
fore the
next Long Delay
Trip Time will again
be
the
"Setting" value.
ln certain applications,
it may be
desirable
to
disable
the LTM function.
The LTM
function can be
disabled
by
first removing the
Rating Plug
from the
Trip Unit
(Figure
3-5a), and
then moving
the LTM
Jumper
found inside
the Rating
Plug cavity on
the
Trip Unit
(Figure
3.5b) to
its "INACTIVE" connection
(Figure
3.5c).
You can enable
the LTM
function
again
at any
time by moving
the LTM Jumper
back
to
its
original
"ACTIVE" connection.
The action
of
the LTM is a
factor to consider
in
pedorming
multiple
Long Delay
Time tests as described
in
Section
8 of this
manual.
3.6
Discriminator
(High
lnitial Current
Release)
When the
Digiirip RMS
Trip Unit is
not equipped
with
an adjustable
instantaneous
protection
set-
ting, i.e.: types
LS or LSG, a
Discriminator Circuit
is
provided.
This circuit
will
prevent
the Circuit
Breaker from
being closed and
latched-in on
a
faulted circuit.
The nonadjustable
release is
preset
at
eleven
(11)times
the installed
Rating Plug
ampere
rating
(ln).
The
Discriminator
is
armed
only
for the first
ten
(10)
cycles following
an initial Circuit
Breaker closing
operation
with a load current
exceeding
approxi-
mately 2O%o of
the Circuit Breaker
Frame or
Sensor
Rating. Should
the Load Current
through
the
Circuit
Breaker drop
to a value
less than this,
the
Discriminator
will re-arm.
Once armed,
it will
remain
armed until
the Load Current
passing
through the Circuit
Breaker exceeds
approximately
2jyo
for 10 cycles.
Any trip operation
initiated by
the Discriminator
will trip the
Circuit Breaker
instantaneously.
The Discriminator can
be selected
by a switch selection
on the
front of
the
Trip
Unit.
Code
a@
BA cA oA E
F
H K
100 25 30 35
40
50 60 75 100
200 50 60
7A
ao 100 120 150
2AA
250 63
75
a8 100 125 150
188
254
300 75 90 105 120 150
140 225
300
400 100 120 140
160 200 240 300
400
600
150
180 210 240 300 360
450 600
800
200
240 280 320 400
4AA 600
800
1000 250 300 350
400 500
600
750 1000
1200 300
360 420 480 600
720
900 1200
1600 400 440 650 640 800
960 1200 1200
2000
500
600 700 800
1000 1200 1200
1200
2400 600
720 840 960 1200 1200
'1200
1200
3000 750
900
1050 1200
1200
'1200
1200 1200
3200 800 960 1120
1200 1200 1200 1200
1200
4000
1000 1200 1200 1204 1200
1200
1200 1200
5000 1200 1200 1200
1200
1200 1200 1200 1200
cRouND
FAULT SETTTNGS
larUeeneSlooo
L!
J
.D
J
a
?
a
o
z
-
k
t
o
l
)
I
Notes:
lD
Except as noied, tolerances on
cunent levels are
!1oo/o of values
O For
Testing Purposes Only;when
using an exle.nalsingle
phase
currentsource lo
check low levelground
lault currenl seitngs,
il is
advisable
to use lhe Auxiliary
Power l\,4odule
(APM).
See
IEST
PBOCEDURES
in instruction
leallet.
O The raiing
plug
is tor 50 Hz and 60
Hz applicalions-
O All tabulated
values are based on the use
ol a residual sensinq
scheme
wth lhe same
rated cufient sensor
in all
phase
and
neutral conduclors.
O CuNes apply
trom
-20
C to
+55
C ambienti
lemperalures
above 95
C cause aulomatic
trip.
@
wittr zone
intertoct<inq on
qround
iault utilized
and no
restraining
signal,
the minimum time band
@applies
-
regardless of
selting.
Fig. 3-4b Digitrip
RMS Ground
Fault Protection
Time-Current
Curve
(G)
Etlective
9/01
ElT.il