A heater control system having an electric heating elements powered from a three-phase alternating current source through a solid state relays connected to the controller and provided with the safety switch assembly is characterized in that each of the heating elements (G) is connected with a separate proportional control solid state relay (K1, K2 K3) and all the proportional control solid state relays (K1, K2, K3) are connected to the controller (S) through the control signal follower (W).