累加定子电流的异步电动机反时限特性热保护

被广泛作为动力源的异步电动机 ,由于其保护装置出现拒动而过热烧毁 ,或者由于保护装置误动跳闸而中断生产过程 ,都将造成较大的经济损失 ,因而解决该问题有较高的实用价值。利用尽可能精确地表示异步电动机发热物理过程的数学模型设计保护装置 ,可以排除多种瞬间电流的干扰 ,在保证异步电动机不受损害的前提下充分发挥其耐热能力。采用热微分方程描述异步电动机定子发热过程 ,提出了求取定子热能累积的算法。计算机仿真表明该方法能较好地模拟电动机发热和散热过程。

Invevse Time Lag Thermal Relaying Protection for Asynchronous Motor with Accumulating Stator Current

Asynchronous motor is widely used to provide power,which is overwarmed up and burnt down because of refusing acting of protector and doesn't work because of the wrong action of the protector, these would bring out bigger economic loss.It is necessary to solve the problems above.A new protector is designtd by utilizing the mathematical model which can nearly exactly express the warming up process of an aysnchronous motor. The warming up process is described by thermal differential equation,and a method which can compute the thermal energy accumulation is presented.The results of computer simulation show this method can really reflect the processes of warming up and cooling down of the stator and can make the asynchronous motor play to its heat-resisting function on the premise of assuring the motor undamaged.