Applications
3.2 Line protection applications of 3VA molded case circuit breakers
3VA molded case circuit breakers with IEC certificate
132
Manual, 03/2019, A5E03603177010-03
Electronic trip units ETU550 LSI and ETU850 LSI
ETU550 LSI 3-pole and 4-pole units:
ETU850 LSI 3-pole and 4-pole units:
Line protection - function LSI
The ETU550 and ETU850 electronic trip units have:
●
Adjustable parameter settings I
r
and t
r
for overload protection (L)
●
Adjustable parameter settings I
sd
and t
sd
for short-time delayed short circuit protection (S)
●
Adjustable parameter setting I
i
for instantaneous short-circuit protection (I)
●
With 4-pole versions: adjustable parameter setting I
N
for neutral conductor protection (N)
(can be activated optionally with 3-pole versions when an external current transformer is
used for the neutral conductor)
