DC Power Supplies provide direct current at varying voltage and current to a device under test. These devices are useful fo testing designs in real world power simutions and can act as a constant battery source when testing DC devices. Power supplies come in variety of configurations and can be used for constant-voltage or constant-current. There are also units with multiple outputs so that one source can supply several outputs to the device under test. Loads are used to test the internal power supply of a unit without risking other elements of the unit.