Accessories
3.5 External accessories
3VA27 molded case circuit breakers & 3WL10 air circuit breakers
120
Manual, 10/2018, L1V30499596002-01
3.5.3.2
External CT for grounding conductors of the main power supply (grounded transformer
star point) G_ret using the ground fault return
Currents in the grounding conductor of the transformer star point can be directly measured
with high accuracy using this toroidal-core transformer and can be evaluated with the
ETU660 (LSIG). The transformer is connected to the auxiliary conductor terminal system of
the circuit breaker. The external current transformer for the grounding conductor of the
power supply is available with rated currents 100 A and 250 A.
Direct measurement of ground currents is an alternative to the vector sum calculation.
T6
External CT for grounding conductors of the main power supply (grounded transformer star
point) GF-CT
3.5.3.3
Summation current transformer Rc CT
Residual currents of 3 A to 30 A can be measured with a summation current transformer and
evaluated by electronic trip units of the 6-series, which is equipped with a rating plug for
residual current protection and the metering function MF Advanced. The transformer is
connected to the auxiliary conductor terminal system of the circuit breaker.
T7
Summation current transformer
