3WL air circuit breakers
3.7 External current consumption with CubicleBUS
3WL/3VL circuit breakers with communication capability - PROFIBUS
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System Manual, 03/2011, A5E01051353-02
Energy requirements
On the ETU45B trip unit, the energy from the transformers is sufficient to activate not only
the protection functions but also the four-line display. Auxiliary power is only required for the
backlighting. If the CubicleBUS is connected with 24 V DC, the display of the ETU45B draws
its power from this voltage.
The pixel-graphics display of the ETU76B requires more power than the energy transformer
can supply. For this reason, the display of the ETU76B only functions when an external
CubicleBUS power supply is connected. This does not affect the protection functions!
NOTICE
Number of CubicleBUS components
If more CubicleBUS components than just the trip unit are used in a SENTRON WL circuit
breaker, this breaker must be supplied with an external 24 V DC auxiliary voltage.
CubicleBUS connection
The CubicleBUS comprises four cores, two for communication and two for the 24 V
DC power supply.
Connect the CubicleBUS as follows to the external terminals X8:1 to X8:4:
●
24 V DC to X8:3
●
Ground of 24 V DC to X8:4
3.7.2
Selecting the power supply
Note the following when selecting the power supply:
●
First, you must use the available CubicleBUS modules to calculate the maximum
continuous current drawn by the CubicleBUS modules from the CubicleBUS supply.
●
The second variable to be calculated is the peak inrush current of all modules. The power
supply must be able to carry the maximum peak inrush current for a period of 100 ms.
The table below contains the details of continuous current drawn and the maximum start-up
current for selecting the suitable power supply for a SENTRON WL circuit breaker with
CubicleBUS.