To calculate the power rating of a PWM (Pulse Width Modulation) pulse train, it is essential to understand the relationship between the duty cycle, voltage, and load resistance. The power can be determined using the formula P = V^2/R, where V represents the effective voltage of the PWM signal and R is the load resistance. The effective voltage can be calculated by multiplying the supply voltage by the duty cycle. Clarification on the specific parameters and context of the PWM application may be necessary for accurate calculations. Understanding these fundamentals is crucial for effective power management in PWM applications.