Siemens SIRIUS 3RU User Manual

Technical data
11.3 Performance features
SIRIUS 3RU thermal overload relays / SIRIUS 3RB electronic overload relays
Manual, 09/2016, A5E03656507420A/RS-AB/003
149
11.3.2
Protection functions - overview
Table 11- 2 Protection functions for 3RU21, 3RB20 / 3RB21 and 3RB30 / 3RB31 overload relays
Feature
Description
3RU21
3RB30 /
3RB31
3RB20 /
3RB21
Tripping in the event of
overload
• Provides optimum current-dependent
protection of loads against impermissibly
high temperature rise due to overload
✓ ✓ ✓
Tripping in the event of
phase asymmetry
• Provides optimum current-dependent
protection of loads against impermissibly
high temperature rise due to phase
asymmetry
✓ ✓ ✓
Tripping in the event of
phase failure
• Minimizes the temperature rise of the three-
phase motor in the event of a phase failure
✓ ✓ ✓
Protection of single-phase
loads
• Enables single-phase loads to be protected
✓ -- --
Tripping in the event of
ground fault
by means of
internal ground-fault
detection (can be
activated)
• 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
-- ✓
(3RB31 only)
✓
(3RB21 only)

Siemens SIRIUS 3RU Specifications

General

Brand	Siemens
Model	SIRIUS 3RU
Category	Control Unit
Language	English