
3RU11, 3RB10, and 3RB12 overload relays
SIRIUS System Manual
4-14
GWA 4NEB 430 0999-02b
Tripping classes
3RU11
The 3RU11 thermal overload relays are available for normal starting in trip-
ping class 10.
3RB10
The 3RB10 electronic overload relays are available in 2 tripping classes:
Tripping class 10 for normal starting
Tripping class 20 for heavy starting
3RB12
The 3RB12 electronic overload relays can be set to different tripping classes
(5/10/15/20/25/30) on the device.
Phase loss sensitivity
The 3RU11/3RB10/3RB12 overload relays are sensitive to phase imbalance.
Note on explosion protection
For releases and relays with current-sensitive delayed tripping, tripping cha-
racteristics must be available at the installation location.
The releases or relays for machines with cage rotors must be selected in
such a way that the release time in the case of a 3-pole load, which is obtai-
ned from the characteristic for the I
A
/I
N
ratio of the machine to be protec-
ted, is not greater than the safe locked-rotor time t
E
specified on the
machine's test label.
Motors must have equipment that protects them even in the event of the
failure of a line conductor.