electric cook tops do not read any external temperature (like the temp of your mash).
it works something like this (numbers are for illustration of the point, and will vary by different makes)
setting an electric cook top to "high" means the element is on 100% of the time. "medium" means 50%- on for 5 seconds, off for 5 seconds. "low" might be on for 2 seconds, off for 8, giving you 20%.
its the same as choosing power levels in your microwave. "50% power" doesnt mean that the microwave is putting out 50% power. its putting out 100% when the emitter is on, but it cycles the emitter on and off.
so there is no "temperature controller" in that cook top. only blind PWM.