The T4000 will automatically adjust the speed of the generator (through the speed controller) in order to match the frequency and phase to the live busbar. The speed output signal is a variable DC voltage, which can be easily matched to the speed trim input of an electronic speed controller. The magnitude of the output voltage is proportional to the frequency/phase deviation. When used together with the T4300 Load Sharer or T4400 Load Sharer, the speed output must be passed through the T4300 or T4400.