Siemens SIRIUS 3RF Series

System overview
1.7 Components and combinations
SIRIUS Innovations
System Manual, 01/2011, A8E56203870002-03
55
1.7.2.3 SIRIUS 3RU2/3RB3 overload relays
3RU2/3RB3 overload relays
Figure 1-23 S0 overload relay
The thermal and solid-state overload relays are available in the modular system with graded
functionality, which reflects their flexible applicability.
Table 1- 13 3RU2/3RB3 overload relays
Area Customer benefits
Functions
 Current-dependent motor protection
 Modular system: Graded functionality for individual requirements
 Integrated temperature compensation
 Integrated remote reset with 3RB31
Dimensioning and
design
 Performance increase:
– S00 (7.5 kW/16 A)
– S0 (18.5 kW/up to 40 A)
 45 mm width (40 A)
 Large wide setting range of 1:4 with 3RB3
 High long-term stability through special bimetals with 3RU2
 Matched and uniform accessories for thermal and solid-state overload
relays
 Screw-type, spring-loaded, ring cable lug connection system (only with
3RU2)
Mounting
advantages
 Optional direct mounting on contactor or stand-alone assembly
 Removable terminals for control circuit wiring (3RB3)
 Same stand-alone assembly support for 3RU2 and 3RB3, with screw-type
and spring-loaded connection systems
Application
areas/customer
benefits
 98% lower power consumption than conventional solutions (3RB3)
 Lower power loss compared to predecessor (5 to 10% with 3RU2)
 Optimum adjustability to the motor current: overlapping ranges up to 60°C,
above that up to 70°C without overlapping
 Comprehensive approvals for global applicability (e.g. ATEX)
Reference
More information ... Is available in ...
About SIRIUS 3RU2/3RB3 overload relays Chapter 5 "SIRIUS 3RU2/3RB3 overload relays
(Page 485)"