Equation 4.7 illustrates the relationship of the power consumption of boost voltage circuit and the ON state time during ( ) of control signal, which the power output is depend on . When is lower than set-point under very high-frequency condition, the output voltage ( ) is lower than 24V, then the relay is cut-off. In case of very low-frequency condition, the protection fuse is operate, which is the value of increase higher than over limit of breakdown point of fuse.