SIRIUS 3RT2 contactors/contactor assemblies 
  2.4 Configuration 
SIRIUS Innovations 
System Manual, 01/2011, A8E56203870002-03 
119 
Ambient temperature  
The 3RT2 contactors are dimensioned as standard for operation at ambient temperatures of 
between -25 °C and +60 °C. Up to 60 °C, side-by-side mounting can be used without any 
restriction. The devices can be stored at temperatures within the range from 
-55 °C to +80 °C. 
Size S00 and S0 contactors can be used at higher ambient temperatures, but various 
constraints must be considered. The 3RT20 contactors can be operated continuously at an 
ambient temperature of Ta > 60 °C, taking the following points into account: 
Thermal load capacity of the main current paths 
The standard contactors are dimensioned for a maximum ambient temperature of 
Ta = 60 °C. In order to use the contactors at higher ambient temperatures of up to 70 °C, the 
rated operational current I
e
/AC-1 or I
e
/DC-1 and the switching frequency z must be reduced. 
The following linear dependencies can be applied here:  
,
H
PD[7X
 
,
H
$&
ವ
r&
7X
,
H
PD[7X
 
,
H
'&
ವ
r&
7X
]
PD[7X
 
]ವ
r&
7X
 
I
e
 max., Ta =  Rated operational current of the contactor at increased ambient 
temperature, to be calculated 
I
e
/AC-1 or I
e
/DC-1 =  Rated operational current of the contactor for relevant utilization category 
and Ta ≤ 60 °C 
Ta =  Actual ambient temperature Tua > 60 °C 
 
The contactors may be operated for 1 hour at an ambient temperature of up to Ta ≤ 80 °C 
without reducing the permissible currents. Nevertheless, the average ambient temperature 
must not exceed Ta ≤ 60 °C for any 24 hour period. Note, however, that contactors which 
contain electronic components or which are combined with electronic accessories 
(e.g. integrated overvoltage attenuation, etc.) may only be operated at an ambient 
temperature of up to Ta ≤ 60 °C. 
Minimum clearances from adjacent components 
The 3RT2 contactors are dimensioned for side-by-side mounting at temperatures of up to 
+60 °C. At higher temperatures a clearance of 10 mm may be required in order to ensure 
better heat dissipation with side-by-side mounting.  
Operating range of the contactor drive 
All SIRIUS contactors comply with the operating range limits of 0.85 to 1.1 x U
S
 (rated 
control supply voltage) stipulated in standard IEC EN 60947. The majority of the devices 
feature an operating range of 0.8 to 1.1 x U
S
, on some versions it is 0.7 to 1.3 x U
S
.  
Reference 
 
More information ...  Can be found in the chapter titled ... 
About minimum clearances from adjacent 
components and the operating range of the 
contactor drive 
Technical data (Page 228)