电机降压启动的原因及为什么要降压启动

对1、2两项，似乎没有根据，现实中上百、数百千瓦的电动机都有全压直接启动的。对3项，变压器是空载吗？对4、5项，实际当中又如何掌控？难道是实际测量吗？
There seems to be no basis for 1 and 2, and in reality, hundreds or hundreds of kilowatts of motors have full voltage direct start. For 3 items, is the transformer no-loaded? For items 4 and 5, how to control them in practice? Is it actually a measurement?

实际上采用降压启动的主要目的，就是避免影响其它设备的正常工作。
In fact, the main purpose of using step-down start is to avoid affecting the normal operation of other equipment.

   在电力系统中，电动机和变压器是两种不可或缺的设备。电动机是将电能转化为机械能的重要装置，而变压器则负责调整电压，以满足不同设备的需求。两者的关系紧密，特别是在电动机的启动过程中，变压器的容量起到了至关重要的作用。
In the power system, electric motors and transformers are two indispensable devices. An electric motor is an important device that converts electrical energy into mechanical energy, while a transformer is responsible for adjusting the voltage to meet the needs of different devices. The relationship between the two is close, especially in the start-up process of the electric motor, the capacity of the transformer plays a crucial role.
   当电动机启动时，它会从电网中吸取大量的电流。如果没有其他设备干扰，仅考虑变压器与电动机之间的关系，电动机的功率可以接近变压器的容量。但实际情况中，还需要考虑功率因数和效率等因素。功率因数反映了电动机实际消耗的功率与视在功率之比，而效率则是电动机输出功率与输入功率之比。通常，电动机的功率会设定为变压器容量的80%，以确保系统的稳定运行。
When the motor starts, it draws a large amount of current from the grid. If there is no interference from other equipment, only the relationship between the transformer and the motor is considered, and the power of the motor can be close to the capacity of the transformer. However, in practice, factors such as power factor and efficiency also need to be considered. The power factor reflects the ratio of the power actually consumed by the motor to the apparent power, while the efficiency is the ratio of the output power of the motor to the input power. Usually, the power of the motor will be set to 80% of the transformer capacity to ensure the stable operation of the system.

   在理想情况下，电动机可以直接启动，或者变压器与电动机同时启动。但在现实世界中，大多数大型电动机启动时，变压器往往还承载着其他负荷。这些其他负荷的多少，会对电动机的启动过程产生直接影响。如果其他负荷较重，那么电动机启动时可能会面临电压下降、电流增大等问题，这可能会对电动机和变压器的运行造成不利影响。
Ideally, the motor can be started directly, or the transformer can be started at the same time as the motor. But in the real world, when most large electric motors are started, the transformer often carries other loads. The amount of these other loads has a direct impact on the starting process of the motor. If other loads are heavy, the motor may face problems such as voltage drop and current increase when starting, which may adversely affect the operation of the motor and transformer.

   因此，在实际操作中，工程师需要综合考虑变压器的容量、电动机的功率、功率因数、效率以及其他负荷的情况，来制定电动机的启动策略。这可能需要通过专业的电力系统分析软件，进行模拟和计算，以确保电动机的顺利启动和电力系统的稳定运行。
Therefore, in practice, engineers need to comprehensively consider the capacity of the transformer, the power of the motor, the power factor, the efficiency and other loads to formulate the starting strategy of the motor. This may require simulation and calculation through professional power system analysis software to ensure the smooth start of the motor and the stable operation of the power system.

   电动机作为工业生产和日常生活中常见的动力源，其启动过程对电力系统的稳定性至关重要。然而，电动机启动时的电流特性可能会对其他电气设备的工作产生显著影响。
As a common power source in industrial production and daily life, the starting process of electric motor is crucial to the stability of the power system. However, the current characteristics of the motor at start-up can have a significant impact on the operation of other electrical equipment.

   首先，我们需要了解电动机启动时的电流特性。笼形电动机是一种常见的电动机类型，其启动电流通常为额定电流的5-7倍。这种大电流会在电网中产生显著的电压降。电压降的大小取决于电流的大小、线路的阻抗以及电源的容量。当电压降达到一定值时，可能会对其他电气设备的正常工作产生不利影响。
First of all, we need to understand the current characteristics of the motor at start-up. Cage motors are a common type of motor, and their starting current is usually 5-7 times the rated current. This high current can create a significant voltage drop in the grid. The magnitude of the voltage drop depends on the magnitude of the current, the impedance of the line, and the capacity of the power supply. When the voltage drop reaches a certain value, it may adversely affect the normal operation of other electrical equipment.
   电压降对其他电气设备的影响是多方面的。首先，电压降可能导致其他电气设备的输入电压降低，从而影响其输出功率和性能。其次，电压降可能导致电气设备的运行不稳定，甚至引发故障。例如，一些对电压敏感的电子设备可能在电压降低时发生误操作或损坏。
The effects of voltage drop on other electrical equipment are manifold. First, voltage drops can cause the input voltage of other electrical devices to drop, affecting their output power and performance. Second, the voltage drop can lead to unstable operation of electrical equipment or even cause failure. For example, some voltage-sensitive electronic devices can be misoperated or damaged when the voltage drops.

   为了减轻电动机启动对其他电气设备的影响，可以采取一些措施。首先，可以优化电动机的启动方式。例如，采用软启动器或变频器等设备，可以平滑地调节电动机的启动电流，从而减小电压降。其次，可以增加电源的容量，以提高电网的供电能力。此外，还可以通过合理的线路设计和布局，减小线路阻抗，从而降低电压降。
In order to mitigate the impact of motor start-up on other electrical equipment, some measures can be taken. First of all, the way the motor starts can be optimized. For example, with devices such as soft starters or frequency converters, the starting current of the motor can be smoothly adjusted to reduce the voltage drop. Secondly, the capacity of the power supply can be increased to improve the power supply capacity of the power grid. In addition, the line impedance can be reduced through reasonable circuit design and layout, thereby reducing the voltage drop.

   在电力系统中，电动机的启动过程经常会伴随着电压降的现象。那么，为什么会产生电压降呢？这背后涉及到电流、变压器容量、以及变压器的现有负荷等多个因素。
In the power system, the start-up process of the motor is often accompanied by the phenomenon of voltage drop. So, why is there a voltage drop? This involves a number of factors, such as the current, the capacity of the transformer, and the existing load of the transformer.

   首先，我们要明白，电压降是由于电流通过导体时，受到导体电阻的阻碍而产生的。在电动机启动的瞬间，由于需要克服机械惯性，电动机的启动电流会远大于其额定电流。这种大电流在通过电网的导体时，会产生较大的电压降。
First of all, we need to understand that the voltage drop occurs when the current passes through the conductor, which is hindered by the conductor’s resistance. At the moment when the motor starts, the starting current of the motor will be much greater than its rated current due to the need to overcome the mechanical inertia. This large current creates a large voltage drop as it passes through the conductors of the grid.

   其次，变压器的容量大小对电压降的产生有着直接的影响。如果变压器的容量足够大，能够提供电动机启动所需的大电流，那么电压降就会相对较小。反之，如果变压器的容量不足，无法提供足够的大电流，就会产生较大的电压降。因此，在考虑电动机的启动方式时，必须充分考虑变压器的容量。
Secondly, the capacity of the transformer has a direct impact on the generation of voltage drop. If the transformer has a large enough capacity to provide the high current required for the motor to start, then the voltage drop will be relatively small. Conversely, if the transformer’s capacity is insufficient to provide enough high current, a large voltage drop will occur. Therefore, when considering the starting mode of the motor, the capacity of the transformer must be fully considered.

   此外，变压器的现有负荷也是决定电压降大小的重要因素之一。当变压器处于空载状态时，其输出电压相对较高，启动电动机时产生的电压降会相对较小。然而，当变压器接近满载或过载状态时，其输出电压会相对较低，启动电动机时产生的电压降就会相对较大。因此，在实际操作中，我们需要根据变压器的现有负荷情况来判断是否需要采取降压启动措施。
In addition, the existing load of the transformer is also one of the important factors that determine the magnitude of the voltage drop. When the transformer is in the no-load state, its output voltage is relatively high, and the voltage drop generated when starting the motor will be relatively small. However, when the transformer is close to full load or overload, its output voltage will be relatively low, and the voltage drop generated when starting the motor will be relatively large. Therefore, in practice, we need to judge whether it is necessary to take step-down starting measures according to the existing load situation of the transformer.

   综上所述，电压降的产生是由于电流通过导体时受到电阻阻碍的结果。而电动机启动时的大电流、变压器的容量大小以及现有负荷等因素都会影响电压降的大小。因此，在判断电动机是否需要降压启动时，我们需要综合考虑这些因素，确保电力系统的稳定运行。同时，这也提醒我们在电力系统的设计和运行过程中，要充分考虑各种因素的影响，确保系统的安全、稳定和高效运行。
In summary, the voltage drop is generated as a result of the resistance hindered by the current as it passes through the conductor. Factors such as the high current when the motor starts, the capacity of the transformer, and the existing load will affect the size of the voltage drop. Therefore, when judging whether the motor needs to be started with a step-down, we need to consider these factors comprehensively to ensure the stable operation of the power system. At the same time, it also reminds us that in the design and operation of the power system, we must fully consider the influence of various factors to ensure the safe, stable and efficient operation of the system.

   在电动机启动的过程中，我们需要综合考虑多个因素来确保电力系统的稳定运行。这些因素包括电动机的启动电流、变压器的容量以及变压器的现有负荷。为了方便分析，我们主要使用电流这个参数作为切入点，因为它直接关系到电压降的大小。
In the process of motor starting, we need to consider multiple factors to ensure the stable operation of the power system. These factors include the starting current of the motor, the capacity of the transformer, and the existing load of the transformer. For the sake of analysis, we mainly use the current parameter as the starting point, because it is directly related to the magnitude of the voltage drop.

   首先，我们知道笼形电动机的启动电流通常是其额定电流的5-7倍。这么大的电流在电网中流动时，会产生显著的电压降。而电压降的大小，直接影响了其他电气设备的正常工作。因此，我们需要对启动电流有一个清晰的认识，以便更好地预测和控制电压降。
First of all, we know that the starting current of a cage motor is usually 5-7 times its rated current. When such a large current flows through the grid, it creates a significant voltage drop. The magnitude of the voltage drop directly affects the normal operation of other electrical equipment. Therefore, we need to have a clear understanding of the start-up current in order to better predict and control the voltage drop.

   其次，我们要考虑变压器的容量和阻抗电压。变压器的容量决定了它能够提供的最大电流。而阻抗电压则是一个重要的参数，它表示了当变压器输出电流为额定值时，电压降的大小。一般的电力变压器阻抗电压为5%左右。这意味着，当变压器的输出电流为额定值时，电压降为5%。因此，我们可以通过阻抗电压来估算不同负荷电流下的电压降大小。
Secondly, we need to consider the capacity and impedance voltage of the transformer. The capacity of a transformer determines the maximum current it is capable of delivering. The impedance voltage is an important parameter, which indicates the magnitude of the voltage drop when the output current of the transformer is the rated value. The general impedance voltage of a power transformer is about 5%. This means that when the output current of the transformer is rated, the voltage drop is 5%. Therefore, we can estimate the magnitude of the voltage drop at different load currents by the impedance voltage.

   接下来，我们引入一个实用的判断方法：假设随着负荷电流的增加，变压器输出电压的电压降是线性变化的。那么，当变压器的输出电流为2倍额定电流时，电压降是5%；3倍电流时是10%；4倍电流时是15%。这个假设虽然简化了实际情况，但它提供了一个简单而有效的方法来估算电压降的大小。
Next, we introduce a practical judgment method: assume that the voltage drop of the transformer’s output voltage changes linearly as the load current increases. Then, when the output current of the transformer is 2 times the rated current, the voltage drop is 5%; 10% at 3 times the current; 15% at 4 times the current. This assumption, while simplifying the actual situation, provides a simple and effective way to estimate the magnitude of the voltage drop.

   最后，我们结合电动机的启动电流和变压器的现有负荷来制定启动策略。如果电动机的启动电流加上现有负荷电流小于变压器3倍额定电流，那么电动机可以直接启动。否则，我们需要考虑采用降压启动或其他方法来减小启动电流，从而减小电压降。
Finally, we combine the starting current of the motor with the existing load of the transformer to develop a starting strategy. If the starting current of the motor plus the existing load current is less than 3 times the rated current of the transformer, then the motor can be started directly. Otherwise, we need to consider step-down start-up or other methods to reduce the start-up current and thus reduce the voltage drop.

   综上所述，通过综合考虑电动机的启动电流、变压器的容量和现有负荷，我们可以更加准确地预测和控制电压降的大小。这为我们制定电动机的启动策略提供了有力的依据，确保了电力系统的稳定运行。
In summary, by taking into account the starting current of the motor, the capacity of the transformer, and the existing load, we can more accurately predict and control the magnitude of the voltage drop. This provides a strong basis for us to formulate the starting strategy of the motor and ensure the stable operation of the power system.