Solution
The PXIe-4051 is equipped with an FPGA that handles the power calculations and limits. When presented with a situation in which the DUT tries to go above the 150W threshold, the PXIe-4051 will automatically lower the sinking current in order to stay within the power limit. If the voltage is raised during operation of the device in order to sink more current, the over-voltage protection will activate and will cause your program to receive an error.
As an additional safety measure, there is a built-in temperature controller, independent of the on-board FPGA, that will shut down the module when exceeding the maximum temperature limit. This would also result in your application receiving an error.