Electric motors faults, analysis and predictive maintenance 1.
Summary
TLDR本视频介绍了异步电动机的故障分析。异步电动机以其低成本、高效率、易于调节和结构简单而广受欢迎。尽管可靠性高,但它们也会遇到机械和电气故障,包括轴承、定子、转子和轴承故障。视频讲解了如何通过振动分析和电流信号分析(MCSA)来识别故障,包括对定子绕组故障、转子偏心和转子条断裂等常见问题的诊断。ADASH VA5Pro振动分析仪能够同时分析振动和电流,自动识别故障原因。
Takeaways
- 😀 异步电机是最常见的电机类型,以其低购买成本、高效率、易于调节和简单而坚固的结构而闻名。
- 🔧 异步电机虽然可靠性高,但也可能遭受机械部件的故障。
- 🔄 电机故障可分为机械和电气起源,以及定子、转子和轴承故障。
- 🤖 轴承的所有部件都可能因机械应力和轴承电流而退化,这些应力可能由不当安装、装配或使用引起。
- 🔌 轴承电流可能由轴电压或半导体转换器的脉冲频率引起的电容电流造成。
- 📊 机械(和一些电气)电机故障在机器的振动频谱中有独特的签名,可以通过振动分析识别。
- 🔍 机械故障如不对准、松动、不平衡和轴承故障的诊断适用于所有其他机械部件。
- 📚 振动分析可以帮助识别电机故障,相关教程视频提供了成为振动分析专家的方法。
- 🌐 一些电气故障也可以在振动频谱中识别,通过带电和不带电的测量可以找到它们。
- 🔢 如果在频谱中发现与电流供应频率(例如50Hz及其谐波频率)完全一致的峰值,这可能是电气问题。
- 🌀 电机电流的频率谱中也有电气(和一些机械)故障的独特签名,可以通过电机电流频谱分析(MCSA)识别。
- 🛠️ 定子故障主要是由于绕组故障,如绕组绝缘断裂,MCSA可以识别绕组故障。
- 🌀 转子故障包括转子偏心和转子条中断,这些故障可能由使用劣质材料、过载或重启动引起。
- 🛡️ ADASH VA5Pro振动分析仪提供了振动和电流分析的独特能力,MCSA模块扩展了分析仪的功能,可以自动识别故障原因。
Q & A
异步电机有哪些常见的优点?
-异步电机的优点包括购买成本低、效率高、调节容易以及结构简单但坚固。
异步电机的故障可以分为哪几类?
-异步电机的故障可以分为机械故障、电气故障以及定子、转子和轴承故障。
轴承故障的主要原因有哪些?
-轴承故障的主要原因包括机械应力和轴承电流,机械应力可能由安装不当、组装不良或使用不当、过载和维护不善引起,轴承电流可能由轴电压或半导体转换器的脉冲频率引起。
什么是振动分析,它如何帮助识别电机故障?
-振动分析是一种通过分析机器的振动频谱来识别故障的技术。所有机械(和一些电气)电机故障在振动频谱中都有独特的签名,可以通过振动分析来识别。
如何通过振动分析来诊断机械故障?
-可以通过观看名为'如何成为振动分析专家'的视频和其他教学视频来了解如何诊断机械故障。
电气故障在振动频谱中是否也有所体现?
-是的,一些电气故障也可以在振动频谱中识别出来。通过在电机供电和断电状态下测量,可以找到具有电气起源的振动特征。
什么是电机电流频谱分析(MCSA)?
-MCSA即电机电流签名分析,是一种通过测量电机电流的时域过程及其随后的频谱分析来识别电机故障的方法。
定子故障中最常见的问题是什么?
-定子故障中最常见的问题是定子绕组故障,尤其是绕组绝缘断裂。
转子故障通常包括哪些类型?
-转子故障通常包括转子偏心(即转子和定子之间的气隙不均匀)和转子条中断。
ADASH VA5Pro振动分析仪有哪些独特功能?
-ADASH VA5Pro振动分析仪可以同时分析振动和电流,并且其MCSA模块可以扩展分析器的功能,允许用户基于频谱进行电流签名分析,或者使用自动检测功能来自动识别故障源。
如何使用ADASH VA5Pro的MCSA模块来识别故障?
-ADASH VA5Pro的MCSA模块能够自动识别转子和定子故障、偏心、断裂的转子条和电能质量等问题。
Outlines
🔧 异步电机故障与分析
本段视频脚本介绍了异步电机的常见故障及其分析方法。异步电机因其低成本、高效率、易于调节和结构简单而广泛应用。尽管它们非常可靠,但仍然可能遇到机械和电气故障,以及定子、转子和轴承的故障。轴承故障可能由机械应力或轴承电流引起,而电机的机械故障可以通过振动分析来识别。此外,一些电气故障也能在振动频谱中被识别出来,例如通过测量电机带电和不带电时的振动信号。MCSA(电机电流信号分析)是一种识别电气和一些机械故障的方法,通过测量定子电流的时间历程并进行频谱分析来识别故障。
🛠️ 异步电机故障的进一步分析
本段内容深入探讨了异步电机的故障分析,特别是定子和转子的故障。定子故障主要是由于绕组绝缘损坏,而MCSA可以识别出绕组绝缘的断裂,这可能导致相位间的绝缘断裂,对电机造成致命伤害。转子故障通常包括转子偏心和转子条中断,这些故障可能由材料质量差、过载或重启动引起。转子条故障可能导致启动性能下降和产生寄生力矩。ADASH VA5Pro振动分析仪提供了振动和电流分析的独特能力,其MCSA模块可以自动检测故障原因,如不平衡、松动、不对中和轴承故障,并且能够自动识别转子和定子故障、偏心、断裂的转子条和电能质量。
Mindmap
Keywords
💡异步电机
💡机械故障
💡电气故障
💡轴承
💡振动分析
💡电机电流频谱分析
💡定子
💡转子
💡转子偏心
💡转子条中断
💡ADASH VA5Pro振动分析仪
Highlights
异步电机是使用最广泛的电机类型,以其低购买价格、高效率、易于调节和结构简单而坚固而著称。
尽管异步电机具有高可靠性,但它们也会遭受机械部件的一些故障。
异步电机故障可分为机械和电气起源的故障,以及定子、转子和轴承故障。
轴承的所有部件都会经历退化,其故障原因可能是机械应力或轴承电流。
机械应力可能由不当安装、装配或使用、过载和维护不当引起。
轴承电流可能由轴电压或由半导体转换器的电源控制产生的脉冲频率引起的电容电流造成。
机械(和一些电气)电机故障在机器的振动谱中有独特的签名,振动分析可以识别它们。
对齐不良、松动、不平衡和轴承故障等故障可以根据适用于所有其他机械部件的相同规则进行诊断。
振动分析可以帮助识别电机故障,相关视频提供了如何成为振动分析专家的指导。
一些电气故障也可以在振动谱中识别出来,通过带电和不带电测量电机可以找到它们。
如果发现与电流供应频率(例如50Hz及其谐波频率)完全相同的峰值,这可能是电气问题。
电机电流的频率谱中有电气(和一些机械)故障的独特签名,MCSA方法可以识别它们。
MCSA代表电机电流签名分析,它通过测量定子电流的时间历程及其随后的频谱分析来识别故障。
定子绕组故障是定子问题的最常见原因,其中断线绝缘是最普遍的故障。
热应力对绝缘的寿命和质量影响最大,瞬态电压的电气应力也是一个不良效应。
异步电机的转子由轴、压在轴上的绝缘片和绕组组成,转子偏心和转子条中断是最常见的故障。
转子条故障可能导致发动机启动性能恶化,并产生寄生力矩,还可能因为缺少条电流路径而在其他条中引起额外的故障。
ADASH VA5Pro振动分析仪提供了在一个设备中分析振动和电流的独特能力,MCSA模块扩展了分析仪的功能。
VA5Pro设备的MCSA模块能够自动识别转子和定子故障、偏心、断条和电能质量等问题。
Transcripts
Hello and welcome to this video about the failure and analysis of asynchronous motors.
Asynchronous motors are the most common type of motors used. They are known for their advantages
such as low purchase price, high efficiency, easy regulation and simple but robust construction.
Despite their high reliability, asynchronous motors suffer from some malfunctions of
machine parts. We can divide failures in an asynchronous motor into failures of
mechanical and electrical origin, as well as stator, rotor and bearing failures.
Let´s start with the bearings. All parts of the bearing are subject to
degradation. The cause of bearing failures can be considered as mechanical stress during rotational
movement and bearing currents. Mechanical stress can be caused by poor installation,
poor assembling, or by improper use, overloading, and poor maintenance.
The bearing currents can be caused by shaft voltages
(due to asymmetric electrical circuits or power supplies) and capacitive currents
(caused by the pulse frequency from the power supply control of semiconductor converters).
All mechanical (and some electrical) motor faults have a unique signature
in the vibration spectrum of the machine and vibration analysis can recognize them.
Failures such as misalignment, looseness, unbalance and bearing faults are diagnosed
according to the same rules applicable for all other machinery parts.
How do we analyze mechanical faults? Get the answer for example from our video named How
to become an expert in Vibration Analysis and our other tutorial videos. What is vibration analysis?
Our series of Vibration analysis for beginners videos will help you to understand this topic.
Some electrical faults are recognizable in the vibration spectrum too.
You should measure the motor with and without a power supply in order to find them.
Some vibration signatures could disappear after power off – those with an electrical origin.
You can also focus on the exact frequency of peaks in the spectrum.
If you find a peak with your exact current supply frequency (for example 50Hz and more
often on its harmonic frequencies) it is probably an electric issue because there is always some
slip on a loaded electric motor and the motor isn´t running on its exact rotation frequency.
Electrical (and some mechanical) motor faults have a unique signature
in the frequency spectrum of the motor current. The MCSA method can recognize them.
MCSA stands for: Motor Current Signature Analysis.
Excessive sidebands are created in electric motors, which distort the frequency spectrum.
Each fault then has its specific signature. Individual defects can be distinguished
from each other according to the amplitude bands and the frequency or other signatures.
The basis of this method is to measure the course of the stator current of one or more
phases in the time domain and its subsequent spectral analysis.
Stator faults Stator winding faults cause the
majority problems in stators. Broken winding insulation is the most common stator fault.
MCSA can recognize broken insulation between threads,
which can lead to broken insulation between phases and it is fatal for the motor.
Thermal stress has the greatest impact on the life and quality of insulation.
Another undesirable effect is the electrical stress of the transient voltage.
In the case of more and more frequent use of inverters for soft-start,
rectangular voltage pulses are modulated at the output of the inverter.
Rotor faults The rotor of an asynchronous motor
consists of a shaft, insulated sheets pressed on the shaft which form the rotor magnetic circuit
and windings. Mostly the winding of the rotor consists of a cage structure,
which is formed by bars, which are connected at the ends.
Rotor eccentricity (meaning the unevenness of the air gap between the rotor and the stator)
and rotor bar interruption are the most common faults.
The cause of these faults can be the use of poor-quality materials,
overloading or heavy starts.
In the case of rotor bars, the fault may increase the resistance of the bar, or completely break
the bar electrical circuit. Rotor bar failures result mainly in engine starting deterioration
and generating parasitic moments. Also, the broken bar causes additional faults in other bars because
the current in them is greater due to the missing bar current path (where one bar is broken).
The ADASH VA5Pro vibration analyzer offers the unique capability of analyzing vibration
and current in one device. In addition, the MCSA module expands the capabilities of the analyzer
and allows you to do analysis of the current signature from the spectrum - based on your
knowledge and experience, or you can use the automatic detection function. It is a similar
feature to the ADASH automatic Fault Source Identification Tool (FASIT) for vibration
analysis. The device can automatically recognize the main causes of failures such as unbalance,
looseness, misalignment and bearing faults. The MCSA module of the VA5Pro device is able
to automatically identify rotor and stator faults, eccentricity, broken rotor bars and power quality.
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