The resistance of the transmission point is the load directly connected in series with the secondary side of the transformer. When the wheel or rail is short-circuited on the rail surface, the secondary voltage of the transformer is completely added to the resistor, which plays the role of loop load and prevents the transformer from burning the equipment or fuse due to the secondary short-circuit without the resistor load. Therefore, the resistance of the power transmission point is not allowed to be adjusted at will, and resistors with different resistance values will be used in different sections according to the rail impedance! The receiver can be adjusted from the maximum voltage to 0, because no matter what short circuit happens to the track, the receiver will lose power supply and its equipment will not be burned. Its resistance is not only an impedance matching function, but also a voltage adjustment function!