Low-melting-point metal liquid rheostat

Abstract

The invention relates to a low-melting-point metal liquid rheostat. The low-melting-point metal liquid rheostat comprises a casing, a static electrode plate, a moving electrode plate, low-melting-point metal, and a screw, wherein the static electrode plate is fixed on the casing; the casing is filled with the low-melting-point metal; the moving electrode plate and the static electrode plate (2) are arranged in pairs; and the moving electrode plate is connected with the screw (5). The moving electrode plate can be driven by the screw to move up and down in the casing so as to change the distance between the static electrode plate and the moving electrode plate and further to change the resistance of the rheostat, thereby achieving the aims of start current regulation and motor soft start. The rheostat system is safer and more stable by using the low-melting-point metal which has the characteristics of high stability, non-toxicity and good thermal and electric conductivity; and the size and the weight of the system are reduced greatly. The low-melting-point metal liquid rheostat provided by the invention can be widely used in the soft start application fields of all kinds of high-voltage and low-voltage large power motors.

Description

technical field [0001] The invention relates to a rheostat, in particular to a liquid rheostat made of low-melting-point metal, which can be applied to the soft start of an AC motor. Background technique [0002] Because of its simple structure, reliable operation, convenient maintenance, and low price, AC motors are widely used as the power of electric drive production machinery, and have a large number of applications in various industries. The motor starts directly under constant voltage, and its starting current is about 6-12 times of the rated current, and its speed needs to rise from zero to the rated speed in a short time, which will produce an impact during the starting process, and it is easy to make the electric drag The transmission mechanism of the object is severely worn or even damaged. In particular, the high-voltage motor will cause the grid voltage to drop under the impact of the high current at the moment of starting, which will affect the normal operation...

AI Technical Summary

Problems solved by technology

The liquid rheostat has the characteristics of simple structure and stepless variable resistance, but the liquid rheostat uses an aqueous solution of sodium carbonate or sodium chloride. On the one hand, due to the strong corrosiveness of the salt solution, corrosion of the travel switch shell and contact with the conductive contact often occur. On the other hand, the salt solution is easy to boil and evaporate at high temperature, so the amount of salt solution needs to be increased to increase the heat capacity, resulting in a bulky equipment; and the salt solution is volatile at room temperature and needs to be continuously replenished, which increases the complexity of the operation

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