The frequency sensitive rheostat is a supporting electrical control device designed exclusively for wound‑rotor asynchronous motors. Its core function is to assist high-power industrial motors in achieving smooth heavy-load startup and reduce startup current as well as mechanical impact. Therefore, its application scenarios are highly concentrated on all types of heavy-duty industrial mechanical equipment with frequent start-stop cycles and continuous operation, covering nearly all heavy industry sectors.
In the hoisting industry, this product serves as a common supporting component for overhead cranes, gantry cranes, port tower cranes, workshop travelling cranes and industrial elevators. Such hoisting equipment features variable loads, frequent start and stop actions and frequent forward-reverse switching. Ordinary startup methods tend to cause fuselage shaking, structural impact and motor overload. The frequency sensitive rheostat can gently control the motor startup process, make hoisting operations smoother and safer, and effectively reduce mechanical vibration and structural fatigue damage.
In the mining and building materials sectors, frequency sensitive rheostats are widely fitted to heavy machinery such as ball mills, crushers, grinding mills, mine hoists and screening equipment. These machines carry extremely high static loads and face great resistance at startup, generating strong instantaneous startup current. Direct startup will easily lead to grid fluctuation, tripping of the power supply and motor thermal damage. When equipped with a frequency sensitive rheostat, the equipment can automatically adjust resistance according to frequency changes throughout the motor startup process and raise rotating speed gradually to overcome mechanical static resistance steadily. This makes it well suited for long-term, high-intensity heavy-duty working conditions.
Large industrial fans, high-pressure water pumps, air compressors and other fluid conveying equipment also constitute major application scenarios. The impellers of this type of equipment have large inertia and high startup loads. Direct startup produces severe mechanical impact and grid disturbance. The adaptive characteristics of the frequency sensitive rheostat realize soft startup, allowing rotating speed to rise progressively and protecting precision transmission parts including motor bearings, impellers and couplings to extend the overall service life of the machine.
Besides, large transmission roller tables, heavy-duty conveying equipment and large stirring machines in metallurgical, chemical, cement and power plants also commonly adopt this product. It should be clarified that the frequency sensitive rheostat is an industrial heavy-duty supporting component. It is not applicable to small civil motors or light-duty equipment and only serves high-power machinery demanding heavy loads and high operational stability. It acts as a low-cost and highly reliable motor startup solution for the heavy industry.