**3. Experimental Setup**

In this paper, the non-unit protection of different low voltage dc grids with multiple power electronic converters, distribution lines and SSCBs is investigated. In this section, the specifications of the different components that make up the experimental setup are presented. Moreover, the operation of the developed SSCBs is experimentally validated.

#### *3.1. Power Electronic Converters Emulated by DC Power Supplies*

The power electronic converters in low voltage dc grids are emulated by SM 500-CP-90 power supplies, which are manufactured by Delta Elektronika. The SM 500-CP-90 power supply is an isolated bidirectional power supply rated for 500 V and 90 A in two quadrants. To emulate the behavior of power electronic converters in low voltage dc grids, these power supplies are operated in constant voltage or constant current mode. In these modes, the power supplies internally limit the current, but they do not limit the current flowing from their output capacitances. This accurately emulates power electronic converters, since their control bandwidth is generally low and the circuit breakers detect and interrupt the fault current before the converters' control can react to the disturbance. A picture of such a power supply is shown in Figure 3.

**Figure 3.** SM 500-CP-90 bidirectional power supply from Delta Elektronika, which is used to emulate the power electronic converters in low voltage dc grids.
