An intermittent operation in which load conditions are regularly recurrent is the definition of

periodic duty

Explanation:

Periodic duty is an intermittent operation in which the duty cycle is repeated identically at regular intervals. for example, it can be a continuous duty, short-time duty or periodic duty. That is the load conditions are regularly recurrent. Varying duty is operation at loads, and for intervals of time, both of which may be subject to wide variation.

Answer;

-Periodic Duty

Explanation;

Duty considered as generic term, for example, can be classified as continuous duty, short-time duty or periodic duty.

-Intermittent periodic duty is a sequence of identical duty cycles, each including a time of operation at constant load and a time de-energized and at rest. The contribution to the temperature-rise given by the starting phase is negligible.