Why does my cooktop element keep cycling on and off even on the highest setting?

This is normal behavior — the temperature limiter operates automatically to protect the glass ceramic surface from extreme high temperature damage. Each radiant heating element has its own sensor that will cycle the element off regardless of the cook setting. If the element cycles more than usual, it may be due to a warped pan base, a pan too small for the element, boiled-dry contents, or a pan material that transfers heat too slowly. (Page 10)