Mounting, wiring, connecting, system interfaces, configuration guidelines 
  12.2 Wiring, connecting 
SIMOCODE pro 
System Manual, 05/2019, A5E40507475002A/RS-AD/004 
233 
12.2.5  Measuring current with an external current transformer (interposing transformer) 
Functional principle 
SIMOCODE pro can be operated with external current transformers. The secondary cables 
of the current transformer are looped through the three feed-through openings of the current 
measuring module, and short-circuited. The secondary current of the external current 
transformer is the primary current of the SIMOCODE pro current measuring module.  
 
Note 
If the main circuit is using rated current, the secondary current of the current transformer 
mus
t be within the setting range of the current measuring module used! 
 
 
Figure 12-29  Measuring current with an external 3UF18 current transformer 
Transformation ratio 
The transformation ratio is calculated using the following formula:  
 
In the following examples, the displayed actual current flowing does not need to be 
converted, even when an interposing transformer is used, since SIMOCODE pro only 
outputs the proportional value, based upon the parameterized current setting I
s
.