Abstract: The system for determining and indicating overload conditions of electrical apparatus immersed to a dielectric liquid contains a heat sensing element in the top portion of the dielectric liquid and a load current sensor. The output signal of the heat sensing element and the output signal of the load current sensor, corrected with due regard to the dependence of the temperature of the winding's hottest spot on the load current, are applied to a switching circuit. The switching circuit contains an alarm circuit and a tripping circuit controlled by low- and high-overload threshold elements selectively operating at successively increasing temperature values of the electrical apparatus' hottest spot. The tripping circuit comprises a device for suppling an alarm signal and/or for deenergizing the electrical apparatus upon completion of the safe service life of the electrical apparatus.