Short Delay Settings; Instantaneous Settings - Eaton 520 Operating Manual

Instruction Leaflet IL01301051E
effective September 2013
ShNro delay seooings
On Digitrip 520 LSI and 520M (R)LSI(G/A) trip units (IZMX...V and
...U) tripping due to the short-circuit current I
time t . This provides selectivity for the short-circuit protection in
sd
switchgear with several grading levels. Available setting values for the
short delay pickup I are:
sd
I = (2/3/4/5/6/7/8/10) x I
sd r
Important: The short delay setting I
There are two different short delay response curve shapes: fixed time
(FLAT) and I t. The shape selected depends on the type of selective
2
coordination chosen. The I t response curve will provide a longer time
2
delay for current below 8 x I
R
Flao respNnsee: o = 0.1/0.2/0.3/0.4/0.5 s
sd
I T = 0.1/0.3/0.5
2
The I t response is applicable to currents less than eight times the
2
ampere rating of the continuous current rating (I
than 8 x (I ) the I t response reverts to the FLAT response.
2
R
N Noee: See section 2, zone interlocking.
Turn rotary switch
to change short
delay current
setting I
sd
Figure 10. Applying ShNro Delay Seooings
Available Settings
2, 3, 4, 5, 6, 7 , 8, 10
Figure 11. ShNro Delay Curreno Seooings
16 EATON www.eaton.com
can be delayed by the
sd
is based on the long delay I
sd
than will the FLAT response curve.
). For currents greater
R
Turn rotary
switch to change
short delay time
setting t
sd
I
SD
In Multiples of Long
Delay Setting (I )
R
Operating Manual for Series NRX
r
Figure 12. ShNro Delay Time Seooings
InsoanoaneNus seooings
If the current setting I
instantaneously.
Available settings values for I
I = (2/3/4/5/6/8/10) x I
i
Turn rotary
switch to change
instantaneous
current setting I
Figure 13. Applying InsoanoaneNus Seooings
Figure 14. InsoanoaneNus Seooings
Trip Units - Digitrip™ 520/520M
t (s)
sd
Available Settings
0.1, 0.2, 0.3, 0.4, 0.5
Seconds With
FLAT Response
l t Shape Returns to FLAT
2
Response at Currents
Higher than 8 x I
R
0.1*, 0.3*, 0.5*
Seconds With
l t Shape
2
* Indicates l t Shape
8 x I 2
R
is exceeded, the circuit breaker is tripped
i
are:
i
; OFF
n
i
I
i
Available Settings
2, 3, 4, 5, 6, 8, 10,
12, OFF
In Multiples
of Rating Plug
Amperes (I )
n