Siemens SENTRON 3VL series - Setting the Protection Parameters for Motor Protection (ETU10 M, ETU30 M and LCD-ETU 40 M)

Parameter assignment / addressing
9.2 Setting the protection parameters for motor protection (ETU10M, ETU30M and LCD-ETU 40M)
3VL IEC molded case circuit breakers
System Manual, 11/2013, 110 0110 - 02 DS 03
123
9.2
Setting the protection parameters for motor protection (ETU10M,
ETU30M and LCD-ETU 40M)
The selection of the molded case circuit breaker is oriented around the rated operating
current of the motor; the releases are specially designed for overload protection of 3-phase
motors.
Overload release I
R
:
The overload release I
R
is set to the rated current of the motor, in the same way as
protection parameters for line and generator protection. The overload protection is finely
adjustable with the left rotary encoding switch (first decimal place) and the center rotary
encoding switch (second decimal place) in the range between I
R
= 0.41; 0.42 to 0.98; 0.99;
1 x I
n
(I
n
= rated breaker current).
Example
Adjusting to the motor current 360 A is carried out for the rotary encoding switch left and
center (ETU10M and ETU30M) (rated breaker current I
n
= 500 A) as follows:
Overload protection setting
Setting I
R
/ rated breaker current I
n
= 360 A / 500 A = 0.72
1. Setting the rotary encoding switch left factor 0.7
2. Setting the rotary encoding switch center factor 0.02
Short-circuit release I
i
Furthermore, instantaneous short-circuit release I
i
can also be set depending on the trip unit.
This setting value refers to the rated current I
n
of the molded case circuit breaker. As with
line and generator protection, the minimum short-circuit must be taken into account when
selecting the setting.
With the ETU30M version, you must note that the setting of the short-circuit release is
selected in combination with the time-lag class. The rotary encoding switch is divided into
three areas here, corresponding to the values 6, 8 or 11 x I
n
. The desired time-lag class can
be selected within these ranges.