Hi Guys

Need some help with argument with engineer.

We ordered Atess combiner Box 16 string. According to datasheet it has a 250A DC breaker. Each string is protected by a fuse. Positive and negative.

We installed a 100m 2 core 95mm2 cable which can handle 257A. When we received the units it came with a 400A breaker. Apparently the new ones have been changed. We argue that the breaker is just acting as a isolator and the protection is done through the fuses. The panels will never deliver more than 250A.

What are your guys opinion? If you can prove your opinion with what stated in SANS it will be great.

 

Thanks

Quote

6.7.1.1 Each phase conductor of an installation, live (unearthed) conductor
of an earthed d.c. system, and conductor in an unearthed d.c. installation
shall be protected against overload and short-circuit currents by one or more
protective device(s). Each protective device shall have a rated current that
does not exceed the lowest of the current-carrying capacities of any of the
conductors of the circuit and shall have a minimum short-circuit rating of
2,5 kA.
In a d.c. installation that has multiple sources of power, each source shall be
protected individually. Protective devices shall be located as closely as
possible to the source terminals, taking all other requirements (such as
battery rooms) into account.
NOTE 1 An overcurrent protective device may be a circuit-breaker that interrupts the
supply to all the phase conductors of a circuit.
NOTE 2 Protection against overload and short-circuit may be provided by separate
devices or by a single device.

I am sure NOTE 2 was intended to be read in terms of one per phase. But it can _probably_ be read as one per source too?