Powering up UUT for the first time can be a risky business as there could be failures, such as shorts between supply lines, that could mean the UUT will never work or require significant expensive reworking. This is especially important when the UUT contains very expensive parts such as high end FPGA or micro processors.
A good test setup should have features to help the user protect the UUT from over-currents and over-voltages in a quick (micro seconds) and controlled manner.
Read more about the problem in the Technical Report <UUT Power up Safety>
Is your UUT protected and safe?