Electrode rod for detecting water-level, method of detecting water-level, method of controlling water-level in a boiler, and method of controlling water-level in a steam separator

An insulating coating formed of engineering plastic with high-heat resistance, high-pressure resistance, and chemical resistance is formed on a surface of a water-level detecting electrode part of an electrode rod for detecting water-level attached to penetrate a metal container communicating with a boiler and including an external power supply connecting terminal part projecting outside the container and the water-level detecting electrode part projecting inside the container. One side of a power supply is connected to the external power supply connecting terminal part, and another side of the power supply is connected to the container for energization. An electrostatic capacity between the water-level detecting electrode and the container is measured by using the insulating coating on the surface of the water-level detecting electrode part as a dielectric. The water-level of water in contact with the water-level detecting electrode part in the container can be detected from the electrostatic capacity.