Transformer primary internal resistance test chart: the resistance in the multimeter is 0.3Ω, the internal resistance of the transformer = the measured resistance of the transformer is 2.6Ω-the internal resistance of the multimeter is 0.3Ω = 2.3Ω. The higher the conductivity of the wire, the larger the wire diameter, and the smaller the internal resistance. Because the transformer is connected in series with the load, when the high-power and high-current output, the internal resistance voltage drop at the input terminal is large, the input terminal voltage is reduced, and the output terminal voltage is decline. For cattle with insufficient power, the voltage drop after loading is greater than for cattle with full power.