Siemens SIRIUS 3RF Series

SIRIUS 3RU2/3RB3 overload relays
5.10 Technical data
SIRIUS Innovations
536 System Manual, 01/2011, A8E56203870002-03
5.10 Technical data
5.10.1 Performance features
5.10.1.1 General data
Table 5- 33 General data for 3RU21 and 3RB30/3RB31 overload relays
Feature Description 3RU21 3RB30/3RB31
Sizes
 Are matched to the dimensions,
connections and technical features of the
other devices in the SIRIUS modular
system (contactors, soft starters, etc.)
 Permit the mounting of slim-line and
compact load feeders in widths of 45 mm
(S00), 45 mm (S0)
 Make configuration easier
S00/S0 S00/S0
Seamless current range
 Allows straightforward and consistent
configuration with one series of overload
relays (for small to large loads)
0.11 to 40 A 0.1 to 40 A
5.10.1.2 Protection functions - overview
Table 5- 34 Protection functions supported by 3RU21 and 3RB20/3RB31 overload relays
Feature Description 3RU21 3RB30/3RB
31
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
equipemnt
 Saves space in the control cabinet
 Reduces wiring outlay and costs
-- ✓
(3RB31
only)