Siemens SIRIUS 3RH Series - Features of Overload Relays

SIRIUS 3RU2/3RB3 overload relays
5.10 Technical data
SIRIUS Innovations
538 System Manual, 01/2011, A8E56203870002-03
5.10.1.5 Features of overload relays
Table 5- 37 Other characteristics of 3RU21 and 3RB30/3RB31 overload relays
Feature Description 3RU21 3RB30/3RB
31
Temperature compensation
 Allows the use of the relays without derating even
at high temperatures
 Prevents premature tripping
 Allows compact control cabinet installation without
clearance between the devices/load feeders
 Simplifies configuration
 Enables space to be saved in the control cabinet
✓ ✓
High long-term stability
 Provides reliable protection of loads even after
years under severe operating conditions
✓ ✓
Wide setting ranges
 Reduce the number of variants
 Minimize the engineering outlay and costs
 Enable savings to be made where storage
overheads, storage costs, and tied-up capital are
concerned
-- ✓
(1:4)
Tripping class CLASS 5
 Enables solutions for motors which start up very
quickly and require special protection measures
-- ✓
(3RB31
only)
Tripping class > CLASS 10
 Enable solutions for heavy-duty starting
-- ✓
Low power loss
 Reduces power consumption (power consumption
is up to 98% less than with thermal overload
relays) and thus energy costs
 Minimizes the temperature rise of the contactor
and the control cabinet - in some cases this may
eliminate the need for control cabinet cooling
 Enables space to be saved through direct
mounting on the contactor even at high motor
currents (i.e. no heat decoupling is required)
-- ✓
Intrinsic supply
 Eliminates the need for configuration and
connecting an additional control circuit
--
1)
✓
Variable setting of tripping classes
(The required tripping class can be
set dependent upon the prevailing
starting conditions using a rotary
switch.)
 Reduces the number of variants
 Minimizes the engineering outlay and costs
 Enables savings to be made where storage
overheads, storage costs, and tied-up capital are
concerned
-- ✓
(3RB31
only)
1)
As SIRIUS 3RU21 thermal overload relays work on the basis of the bimetal principle, they
do not require a control supply voltage.