Development Of New Liquid-state Soft Starter

This paper state the current situation of research and development trend on soft start at home and abroad, and introduces the characteristics of some usual modes of motor soft start, which include frequency conversion soft start mode, liquid resistance soft start mode, thyristor in series soft start mode, magnetic-controlling soft start mode and variable resistance soft start mode.Based on technical nature, efficiency, reliable three aspects overall evaluation, a new liquid-state soft starter is studied in the paper. It is made by connecting in series a special resistance to motor stator circuit. Using mechanical driving device, the distance between movable polar plate and fixed polar plate can be changed equably and resistance can be reduced stepless from maximum to zero. Then motor can be accelerated evenly, started smoothly until its speed reaches rated speed, that is to say, it realizes soft start. The velocity modulation way uses the water resistance adjustment resistance number substitution rheostat adjustment resistance number, because and has solved the resistance fluid temperature decrease radiation problem, enables the product to be possible to be suitable in large and middle scale winds thread the type electric motor or circles the cage type electric motor's starting velocity modulation. In the actual debugging resistance number process, may add alkali surface in the water to adjust the resistance value the size, and according to the actual electric current, the loss of voltage size adjusts the R value, until makes the best start progress.The liquid-state soft starter in this paper has many characteristics such as low starting current(it is up to 3.5 times than the rated current),start smoothly, small impact on electric network and high cost performance(its price is only 10 percent of that of frequency converter).The designed liquid-state soft starter is simulated and experimented in my work. The experimental results show that the designed liquid-state soft starter can realize soft start of high-voltage motor and all kinds of marks are reached.