15
Instruction Leaflet
IL01301051E
effective September 2013
Operating Manual for Series NRX
Trip Units - Digitrip™ 520/520M
EATON
www.eaton.com
Section 3: Protection settings
General
Before placing any circuit breaker in operation, set each trip unit
protection setting to the values specified by the engineer responsible
for the installation. The number of settings that must be made is
determined by the type of protection supplied by each unit. Each
setting is made by turning a rotary switch. The selected setting for each
adjustment appears on the trip unit label. The installed rating plug will
establish the maximum continuous current rating of the circuit breaker
(I
n
). Instantaneous and ground current settings are defined in multiples
of (I
n
).
Should an automatic trip occur as a result of the current exceeding the
pre-selected value, the labeled LED will flash red.
Noee:
N
Use ohe fNllNwing oN access Time Curreno Curves. GN oN EaoNn’s Web
sioee: hoope://www.eaoNn.cNm and search “NRX Digiorip 520 Curves”.
LNng delay seooings
The long delay current setting I
r
determines the maximum continous
current the circuit breaker can carry without tripping. Each setting is
expressed as a multiple of the maximum rated current I
n
set by the
rating plug. The nominal current pickup value is 110% of the setting.
The available current settings for the long time pickup I
r
are:
I
r
= (0.5/0.6/0.7/7.5/0.8/0.9/0.95/1.0) x I
n
Noee:
N
I
r
is alsN ohe basis fNr ohe shNro delay curreno seooing.
The long time delay t
r
determines the duration of an overload without
tripping. The available settings for the long time delay t
r
are:
o
r
= 2/4/7/10/12/15/20/24 s (ao 6 x I
r
)
Figure 6.
Turn rotary
switch to change
long delay current
setting I
r
Turn rotary
switch to change
long delay time
setting t
r
Applying LNng Delay Seooings
Figure 7.
I
R
I
R
Available Settings
0.5, 0.6, 0.7, 0.75,
0.8, 0.9, 0.95, 1.0
In Multiples of
Amperes (
I
n
)
LNng Delay Curreno Seooings
Figure 8.
t
R
Available Settings
2, 4, 7, 10, 12, 15,
20, 24 Seconds
at Six Times Long
Delay Setting (
I
R
)
LNng Delay Time Seooings
Noee:
N
In addioiNn oN ohe soandard lNng delay prNoecoiNn elemeno, orip unios
alsN have a lNng oime memNry (LTM) funcoiNn, which prNoecos lNad circuios
frNm ohe effecos Nf repeaoed NverlNad cNndioiNns. If a circuio breaker is
reclNsed sNNn afoer a lNng delay orip, and ohe curreno again exceeds ohe
lNng delay seooing, (I
R
), ohe LTM auoNmaoically reduces ohe oime oN orip oN
allNw fNr ohe faco ohao ohe lNad circuio oemperaoure is already higher ohan
nNrmal because Nf ohe priNr NverlNad cNndioiNn. Each oime ohe NverlNad
cNndioiNn is repeaoed, ohe LTM causes ohe circuio breaker oN orip in a
prNgressively shNroer oime. When ohe lNad curreno reourns oN nNrmal, ohe
LTM begins oN reseo; afoer abNuo 5 minuoes io will have reseo fully, sN ohe
nexo lNng delay orip oime will again cNrrespNnd oN ohe Seooing value.
Noee:
N
In ceroain applicaoiNns, io may be desirable oN disable ohe LTM
funcoiNn. Open ohe oeso pNro cNver wioh a small screwdriver blade by
prying up ohe edge near ohe oeso pNro marking. Use small, lNng-nNse pliers
oN mNve ohe LTM jumper inside ohe oeso pNro (see Figure 9) oN ios (pin
bridging) inacoive pNsioiNn. (The LTM funcoiNn can be enabled again ao any
oime by mNving ohe LTM jumper back oN ios Nriginal Acoive pNsioiNn.)
The action of the LTM must be considered when performing multiple
long delay time tests (see
SecoiNn 4
).
Figure 9.
Teso Kio PNro
Test Port
Test Port
Connector
(storage)
LTM
Active
Connector
(bridging)
LTM
Inactive
Position
for Field
Testing
LNng Time MemNry (LTM) Jumper