Siemens SENTRON 3VL System Manual page 59

Figure 5-6
Measurement method 2: Direct detection of the ground-fault current via a current transformer at the
grounded star point of the transformer
The current converter is installed direct at the grounded star point of the transformer.
Figure 5-7
3VL molded-case circuit breakers
System Manual, 03/2009, 110 0110 - 02 DS 01
4-pole circuit breaker, current converter installed internally
3-pole circuit breaker, current converter at the grounded star point of the transformer
Functions
5.1 Current protection
59