Soft starter of three-phase anti parallel thyristors as a regulator in this circuit, such as three-phase fully controlled bridge rectifier circuit, the motor soft starter to start with, the thyristor output voltage increases gradually, the motor accelerates gradually, until the whole thyristor conduction, the motor works in the mechanical properties of rated voltage, realize smooth start, reduce the starting current, to avoid starting over-current trip. Their access to power and between motor stator.

Chinese a soft start

A soft starter

For pressure regulator

Catalog

The 1 concepts

2 Introduction

3 starting method

4 working principle

The traditional distinction between 5

Discipline without shock current

After a soft stop function

After starting adjustable parameters

6 large motor

7 types of detailed interface

8 energy saving

9 routine maintenance

The 1 concepts

The editor

The voltage from zero up to the rated voltage, the starting current in the starting process of motor, the past can not control overload current into the control. And can be adjusted according to the size of the starting current. The whole process of the motor starting torque is not the existence of the impact, but the smooth running. This is the soft start. [1]

2 Introduction

软启动器在起动电机时，通过逐渐增大晶闸管导通角，使电机起动电流从零线性上升至设定值。对电机无冲击，提高了供电可靠性，平稳起动，减少对负载机械的冲击转矩，延长机器使用寿命。

即平滑减速，逐渐停机，它可以克服瞬间断电停机的弊病，减轻对重载机械的冲击，避免高程供水系统的水锤效应，减少设备损坏。

根据负载情况及电网继电保护特性选择，可自由地无级调整至最佳的起动电流。

当前我国经济已经进入了一个新的发展阶段，大型企业和大型装备越来越多，大型电机（5000kW～60000kW）的应用越来越多，大型电机的起动方法也越来越受到人们的重视。

社会发展是有阶段性的。在不同阶段，人们的生产手段、生产工具和生活用品都有很大的不同。上世纪80～90年代，我国的经济实力尚较薄弱，当时的小水泥和小钢铁发展很快，1000kW～4000kW电机的应用增长很快，与当时的经济基础相适应的液态起动装置出现，它经济实用，解决了电机起动中的一些问题。对当时的经济发展起到了一定的作用。到世纪之交时期，我国经济实力已有较大的发展，生产手段和生产工具亦有了较大发展，电机容量也有了很大增长，人们开始不满足液态起动装置的低性能，于是晶闸管串联式（固态）软起动装置的应用开始增加，继而又出现了开关变压器式软起动装置和磁饱和电抗器式（磁控）起动装置，变频装置用于电机软起动的情况也越来越多，当前这四种产品是大型电机起动市场的主流产品，液态起动装置则应用在小型（5000kW以下）电机上较多。另外，两种老式起动方法（自耦变压器和变压器-电动机组）也常常出现在20000kW以下电机的起动上。

大型电机驱动的设备一般都是企业的核心设备，直接影响企业的生产状况，因此人们应该对其起动给予特别的关注，合理的选择起动装置将给企业带来很大的经济效益。但是电机起动技术毕竟不是一个企业的核心技术，许多企业的电气工作者很少有时间来研究各种起动方法之间的差别，往往会造成不恰当的选择，有时甚至不得不做出第二次选择，给企业造成不应有的损失。因此，如实地说明各种起动方法的性能及其差别是非常重要的。

电动机直接全压起动的危害性及软起动好处

⒈ 引起电网电压波动，影响同电网其它设备的运行

交流电动机在全压直接起动时，起动电流会达到额定电流的4~7倍，当电机的容量相对较大时，该起动电流会引起电网电压的急剧下降，影响同电网其它设备的正常运行。

软起动时，起动电流一般为额定电流的2~3倍，电网电压波动率一般在10%以内，对其它设备的影响非常小。

⒉ 对电网的影响

对电网的影响主要表现在两个方面：

①超大型电机直接起动的大电流对电网的冲击几乎类似于三相短路对电网的冲击，常常会引发功率振荡，使电网失去稳定。

②起动电流中含有大量的高次谐波，会与电网电路参数引起高频谐振，造成继电保护误动作、自动控制失灵等故障。

软起动时起动电流大幅度降低，以上影响可完全免除。

⒊ 伤害电机绝缘，降低电机寿命

①大电流产生的焦耳热反复作用于导线外绝缘，使绝缘加速老化、寿命降低。

The editor

Soft starter (soft starter) is a set of motor soft start, soft stop, a novel motor control device in one of the many kinds of protection function, called Soft Starter. The main structure is connected in series between the power supply and the controlled motor phase anti parallel thyristors and the electronic control circuit. The use of different methods, control of three phase anti parallel thyristor conduction angle, so that the motor input

Voltage according to different requirements change, you can achieve different functions. The soft starter and frequency converter are two completely different products. Frequency converter is used to control the output voltage of the place, not only the change and change the frequency; the soft starter is actually a regulator, for motor starting, the output voltage does not change the frequency change. Frequency converter soft starter with all functions, but its price is more expensive than the soft starter, the structure is also more complex. The motor soft starter is used on the soft starter is connected between the power supply and controlled motor, its internal control thyristor conduction angle, so that the motor input voltage from zero to a preset function gradually increased, until the end of the motor starting, give full voltage, which is the soft start, soft starting process, the motor starting torque increased speed, increased gradually.