Protection Functions - Overview - Siemens SIRIUS 3RU Manual

11.3.2

Protection functions - overview

Table 11- 2 Protection functions for 3RU21, 3RB20 / 3RB21 and 3RB30 / 3RB31 overload relays
Feature
Tripping in the event of
overload
Tripping in the event of
phase asymmetry
Tripping in the event of
phase failure
Protection of single-phase
loads
Tripping in the event of
ground fault
by means of
internal ground-fault
detection (can be
activated)
SIRIUS 3RU thermal overload relays / SIRIUS 3RB electronic overload relays
Manual, 09/2016, A5E03656507420A/RS-AB/003
Description
Provides optimum current-dependent
•
protection of loads against impermissibly
high temperature rise due to overload
Provides optimum current-dependent
•
protection of loads against impermissibly
high temperature rise due to phase
asymmetry
Minimizes the temperature rise of the three-
•
phase motor in the event of a phase failure
Enables single-phase loads to be protected
•
Provides optimum protection of loads in the
•
event of high-impedance faults to ground
caused by moisture, condensation,
damaged insulation, etc.
Eliminates the need for additional special
•
equipment
Saves space in the control cabinet
•
Reduces wiring time and wiring costs
•
11.3 Performance features
3RU21 3RB30 /
3RB31
✓ ✓
✓ ✓
✓ ✓
✓ --
-- ✓
(3RB31 only)
Technical data
3RB20 /
3RB21
✓
✓
✓
--
✓
(3RB21 only)
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