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起重机具有承载能力大,工作可靠性高等优点。传统起重机的电控系统采用转子回路串接电阻进行有级调速,控制方式为继电一接触器控制,这种控制方式的起重机调速不理想,所串电阻长期发热,效率低;电动机及所串电阻烧损和断裂故障时有发生。是利用PLC实现起重机的力矩保护和自动变速,在解决力矩保护方面,利用能量平衡方程,把重量信号检测转变成测电动机功率信号,再传递到计算机的输入接口,利用计算机进行检测重量是否超标;并利用功率变送器转换成标准电压信号,再利用定、转子之间的数学关系,采用旋转变压器来在线检测起重臂的角度变化,并将信号传递到计算机,进行检测幅度是否达到极限,最终实现力矩保护。
Crane has a large carrying capacity, high reliability and other advantages. The traditional crane’s electronic control system uses the rotor circuit series resistance for step-by-step speed regulation. The control method is relay-contactor control. The crane speed of this control method is not ideal, the resistance of the string long-term fever, low efficiency; motor and The string resistance burning and breakage occurred from time to time. Is to use PLC to realize crane torque protection and automatic transmission. In solving torque protection, using the energy balance equation, the weight signal detection is converted into the motor power signal, and then transmitted to the computer’s input interface, using the computer to detect whether the weight exceeds the standard; And use the power transducer to convert into a standard voltage signal, and then use the mathematical relationship between stator and rotor, the use of resolver to detect changes in the angle of the boom, and the signal is transmitted to the computer to detect whether the limit reached, Ultimate torque protection.