Siemens SENTRON 3WL10 - External Current Transformers; Rogowski CT solo External Neutral

Accessories
3.5 External accessories
3VA27 molded case circuit breakers & 3WL10 air circuit breakers
Manual, 10/2018, L1V30499596002-01
119
3.5.3
External current transformers
①
Rogowski CT solo external neutral
②
CT for direct measurement of the ground-fault current in the grounded transformer star point (G_ret), ground return
method
③
Summation current transformer for direct residual current measurement across all phases (Rc CT)
The direct measuring methods (② and ③) are more precise in determining the ground-fault
current (for details, see Section Parameters of the trip units (Page 72)).
3.5.3.1
Rogowski CT solo external neutral
The optional external current transformer for N conductor is only for three-pole circuit
breakers. It enables protection of the neutral conductor from overload and short-circuit by the
ETU of the circuit breaker. The transformer is connected directly to the auxiliary conductor
terminal system. It is suitable for all electronic trip units of the 3- and 6-series.
The external current transformer for N conductor is also used for determining ground-fault
currents by calculation of the vector sum of the currents for trip units with a G protection
function (ETU360 and ETU660).
T5
External current transformer for N conductor