SIRIUS 3RA28 function modules for mounting on 3RT2 contactors   
7.2 Product description 
  SIRIUS Innovations 
642  System Manual, 01/2011, A8E56203870002-03 
7.2  Product description 
Applications 
Function modules are used to perform various control jobs on automatic production lines and 
for processing machines. They are suited to all time-delayed switching operations in control, 
starting, protection, and regulation circuits, and ensure a high degree of repeat accuracy for 
delay times, once they have been set. 
Function modules are divided into those with a communication connection and those without 
a communication connection. 
 
Function modules   
Solid-state timing relays with semiconductor 
output 
Solid-state time-delay auxiliary switches 
3RA28 function modules 
Function module for star-delta (wye-delta) start 
Function modules for AS-Interface 3RA27 function modules with communication 
connection 
Function modules for IO-Link 
This chapter describes 3RA28 function modules without a communication connection. You 
will find information about function modules with a communication connection in the 
corresponding manuals (see Reference). 
Function 
Function modules are used to delay switching functions. 
System integration 
The 3RA28 function modules have been matched to the contactors in the 3RT2 and 3RH2 
series both electrically and mechanically and can be integrated in the feeders by directly 
mounting them on contactors. The function modules can be used for size S00/S0 contactors.  
The 3RA27 function modules can only be used for communication-capable contactors. 
Connection system 
Users can choose either function modules with screw-type connection system or function 
modules with spring-loaded connection system. 
Reference 
More information ...  Is available in ... 
About 3RA27 function modules for AS-Interface  Manual "Function Modules for AS-Interface" 
(http://support.automation.siemens.com/WW/view
/en/39318922) (3ZX1012-0RA27-0AC0) 
About 3RA27 function modules for IO-Link  Manual "Function Modules for IO-Link" 
(http://support.automation.siemens.com/WW/view
/en/39319600) (3ZX1012-0RA27-1AC1) 
About function modules for reversing starting   The chapter titled SIRIUS 3RT2 
contactors/contactor assemblies (Page 110)