Zero-volt load means that the electronic load can output a rated full current at a very low input voltage, and the current can be as high as hundreds of amperes. The electronic load has an unavoidable minimum internal resistance due to the conduction-drain-source internal resistance of the field effect transistor, and requires a certain minimum DC input voltage (UMIN) to enable the load to absorb the full rated current. Below this minimum operating voltage, the load current will decrease linearly. Usually below 3V, the load transistor is in the saturated working range, the current control ability becomes weaker, and the dynamic response becomes worse. The power supply voltage must be greater than the minimum operating voltage of the load, and the voltage drop of wires, relays, connectors, etc. under high current needs to be considered.