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EntelliGuard* L

Selectivity / Discrimination

Selectivity / Discrimination EntelliGuard Air Circuit Breakers
In a low voltage distribution network it is necessary that A combination of the high precision and multiple bands of
during a fault, the protection device nearest to the fault the EntelliGuard Electronic Trip Unit allow full selectivity to be
reacts whilst all others remain closed. achieved between closely rated devices over multiple levels.

This capability is called discrimination or selectivity. The table included here indicates the recommended settings
of the upstream EntelliGuard Breaker as a a ratio to that of
If this requirement is not met a fault in one arm of the the downstream protection devices.
distribution system could cause a number of upstream A second table on page 45 indicates the discrimination/
protection devices to react and open. A relatively minor fault
Application Guide Downstream Trip Unit denomination determining setting ratio setting band setting ratio setting band I setting
in one arm of a complete distribution will then cause a power
selectivity that can be achieved with these settings.
interruption across a major part of the installation.
The tables can replace the complex and time consuming
method of comparing multiple time current curves across
many levels.
Recommended EntelliGuard settings
Setting
Settings
Ist
LTDB
STDB
device
Ir or Ie
delectivity
Record Plus
Ir
FD and FE frame
Ratio and Band
5kA -FD160,
C22
1.6 x
Ratio and Band
Ir
GTM
FD and FE frame LTMD Im Ratio and Band 1.6 x C22 1.6 x Band 2 Minimum setting
Im Ratio and Band 1.6 x Band 2 7kA - FE160,
SMR Ir Ratio and Band 1.3 x 9kA - FE250
Intro FE frame PremEon S LTD Motor Band C14 or I = ‘OFF’
PremEon S
Ist Ratio and Band 1.35 x Band 2
Ir
FG frame SMR1 LTD Motor Ratio and Band 1.3 x C14
Band
PremEon S Ist Ratio and Band 1.35 x Band 3
A LTD cl.1.25 Band 1.3 x C3
Ratio
Ir
LTD cl. 2.5 Band C5 Minimum setting
LTD cl. 5 Band C8 14kA -FG400,
LTD cl.10 Band C12 18kA - FG630
B FG frame SMR2 LTD cl.20 Band C16 or use ZSI
Band
LTD cl.30
C18
Ist Ratio 1.35 x or I = ‘OFF’
STD=420ms Band Band 13
STD=310ms Band Band 11
C STD=210ms Band Band 9
Band 6
STD=120ms
Band
STD=40ms Band Band 3
Ir Ratio and Band 1.4 x C8
FK frame SMR1e Ist Ratio 1.35 x
D STD Band 1.4 x Band 7 Minimum
setting
Ratio
Ir
LTD cl. 5 Band C8 18kA -FK800
LTD cl.10 Band C12 20kA - FK1000
LTD cl.20 Band C19 20kA - FK1250
E FK frame SMR1s LTD cl.30 Band C22 28kA - FK1600
or use ZSI
Ratio
Ist
STD=300ms Band Band 12 or I = ‘OFF’
STD=200ms Band Band 10
STD=100ms Band Band 7
X LTD class Ratio 1.25 x 2 higher
Ir
Band
EntelliGuard GT-L, -E, -S Ist Ratio 1.25 x Use ZSI
‘-N, -H, -HE or I = ‘OFF’
STD band min, until 11 Band 2 higher
STD band ≤12 1 higher
Industrial fuses ---- Current rating Ratio and Band 2 x F20 ST = 8 x Ir, STDB band 5 and I = 12 x Ie
GL/Gg type
D.4