The current passing through the rectifier element in the conductive direction is called the forward current. This current is pulsating, and its average value is called the forward current average value, and its peak value is called the forward current peak value. In order to prevent the power consumption of the rectifier element from exceeding the allowable value, the average value of the forward current passing through the rectifier element should be less than its allowable value. For some rectifier elements that are limited by the cathode emission capacity (or cathode collapse), its forward current peak value should not exceed the allowable value.
The forward current average value and peak value, in a given rectifier, vary in direct proportion to the DC current (referred to as the rectifier current) required by the rectifier load. Therefore, in order to ensure the safe operation of the rectifier element, the value of the rectifier current is specified when designing the rectifier. This value is called the rectifier current (or output current) rating of the rectifier.