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1、INDUCTION MOTOR STARTING METHODS AND ISSUES感应电动机的起动方法和问题Abstract Many methods can be used to start large AC induction motors. Choices such as full voltage, reduced voltage either by autotransformer or Wyes - Delta, a soft starter, or usage of an adjustable speed drive can all have potential advantag
2、es and trade offs. Reduced voltage starting can lower the starting torque and help prevent damage to the load. Additionally, power factor correction capacitors can be used to reduce the current, but care must be taken to size them properly. Usage of the wrong capacitors can lead to significant damag
3、e. Choosing the proper starting method for a motor will include an analysis of the power system as well as the starting load to ensure that the motor is designed to deliver the needed performance while minimizing its cost. This paper will examine the most common starting methods and their recommende
4、d applications.摘要： 许多方法可用于启动大型交流感应电动机。选择如全电压，通过自耦变压器或Y形三角电压降低，软起动器，或可调速驱动器的使用都可以有潜在的优势和权衡。降压起动可以降低起动转矩，防止损坏负载。此外，校正电容器可用于降低功率因数，但必须注意正确的尺寸。错误的电容器的使用可能会导致重大损失。选择适当的启动方法，电机将包括为保证电机的设计提供了所需的性能的同时，最大限度地降低其成本的初始荷载的动力系统分析。本文将最常用的起动方法和推荐的应用研究。Index Terms: motor starting. Reduced voltage start auto transfor
5、mer, wyes-delta, power factor correction索引条款：电动机起动。降压起动自耦变压器，Y形三角洲，功率因数校正INTRODUCTION There are several general methods of starting induction motors: full voltage, reduced voltage, wyes-delta, and part winding types. The reduced voltage type can include solid state starters, adjustable frequency dri
6、ves, and autotransformers. These, along with the full voltage, or across the line starting, give the purchaser a large variety of automotives when it comes to specifying the motor to be used in a given application. Each method has its own benefits, as well as performance trade offs. Proper selection
7、 will involve a thorough investigation of any power system constraints, the load to be accelerated and the overall cost of the equipment.简介：有起动异步电动机的几种常见方法：全电压，降低电压，Y形三角洲，和部分绕组类型。低电压型可包括固态启动器，变频驱动器，和自耦变压器。这些，连同全电压，或直接起动，给买方的汽车种类繁多的时候指定在给定的应用程序中使用的电机。每种方法都有其自身的利益，以及性能的权衡。正确的选择会涉及的任何权力制约制度进行彻底的调查，以加速负
8、载设备的整体成本。In order for the load to be accelerated, the motor must generate greater torque than the load requirement. In general there are three points of interest on the motors speed-torque curve. The first is locked-rotor torque (LRT) which is the minimum torque which the motor will develop at rest
9、for all angular positions of the rotor. The second is pull-up torque (PUT) which is defined as the minimum torque developed by the motor during the period of acceleration from rest to the speed at which breakdown torque occurs. The last is the breakdown torque (BDT) which is defined as the maximum t
10、orque which the motor will develop. If any of these points are below the required load curve, then the motor will not start.为了使负载能加速，电机必须产生更大的扭矩比负荷要求。一般有三点对电机转速的扭矩曲线的兴趣。第一个是锁定转子扭矩（LRT），最小转矩，电机将在剩下的所有的角位置的转子。二是拉转矩（放），定义为最小转矩由电动机在加速期从其余的速度，转矩发生。最后是击穿扭矩（BDT）被定义为最大转矩，电机的发展。如果这些点所需的负荷曲线的下方，然后电机不能启动。The t
11、ime it takes for the motor to accelerate the load is dependent on the inertia of the load and the margin between the torque of the motor and the load curve, sometimes called accelerating torque. In general, the longer the time it takes for the motor to accelerate the load, the more heat that will be
12、 generated in the rotor bars, shorting ring and the stator winding. This heat leads to additional stresses in these parts and can have an impaction motor life.这需要对电机的加速负载的时间是依赖于负载的惯量和电动机的转矩与负载曲线之间的边缘，有时也被称为加速转矩。一般来说，越需要电机的加速负载时，其会在转子产生更多的热量，短路环和定子绕组。这种热导致这些部件的附加应力，可以有一个影响电机的寿命。II. FULL VOLTAGE The f
13、ull voltage starting method, also known as across the line starting, is the easiest method to employ, has the lowest equipment costs, and is the most reliable. This method utilizes a control to close a contactor and apply full line voltage to the motor terminals. This method will allow the motor to
14、generate its highest starting torque and provide the shortest acceleration times. This method also puts the highest strain on the power system due to the high starting currents that can be typically six to seven times the normal full load current of the motor. If the motor is on a weak power system,
15、 the sudden high power draw can cause a temporary voltage drop, not only at the motor terminals, but the entire power bus feeding the starting motor. This voltage drop will cause a drop in the starting torque of the motor, and a drop in the torque of any other motor running on the power bus. The tor
16、que developed by an induction motor varies roughly as the square of the applied voltage. Therefore, depending on the amount of voltage drop, motors running on this weak power bus could stall. In addition, many control systems monitor under voltage conditions, a second potential problem that could take a running motor offline during a full voltage start. Besides electrical variation of the power bus, a potential physical disadvantage of an across the line starting
