An integrator for monitoring at least one parameter of an electrical signal in an electrical conductor in protective relay application. The integrator includes an integrator circuit having an input for receiving a signal from a current sensor coupled to the electrical conductor. A switch circuit has an input coupled to the output of the integrator circuit, wherein the switch circuit is controlled by the output of a temperature detection circuit. A power stage circuit has an input coupled to the output of the switch circuit, wherein the temperature detection circuit is coupled to a heating element of the power stage circuit through a temperature sensor, and the heating element is attached to a channel-shaped heatsink for heat dissipation.