Accessories
4.11 Accessories for the ETU300 and ETU600 electronic trip units
3WA1 air circuit breaker
Equipment Manual, 02/2023, 92310000002-06
349
4.11.2 External current sensor for neutral pole
4.11.2.1 Description
Note
This accessory is only
intended for 3-pole circuit breakers.
The external current sensor for the neutral conductor (N-CT) enables protection of the
neutral conductor against overload and short circuit by the ETU electronic trip unit of the
circuit breaker. This current sensor is used for calculating ground-fault currents using
the vectorial sum (GF Residual) and for neutral conductor protection with the electronic
trip unit.
The external current sensor for the neutral conductor is available in two versions:
• Current sensor for busbar mounting
The sensor is pushed onto the busbar and bolted in place.
• Current sensor for busbar connection
The sensor has a short copper connection element which is connected to two busbar
ends.
The external sensor for the N conductor is connected to secondary disconnect terminals
X8-9 and X8-10 of the circuit breaker.
The current sensor is supplied with a 2 m long twisted connection cable that is fitted
with the appropriate plug-in connector for the sensor.
You will find more information in the operating instructions available on the internet
(https://support.industry.siemens.com/cs/ww/en/view/109783671
).
4.11.2.2 Technical specifications
You can find the dimensions in Chapter External current sensor for the neutral pole (N-
CT) (Page 482).
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