BISOPE series 66 How to set the appropriate frequency for measurement S...

BISOPE series 66- How to set the appropriate frequency for measurement (Setting the maximum frequency for vibration measurement)

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If you measure vibration using an FFT vibration meter, there are many things to consider in advance compared to measuring other physical quantities (temperature, displacement, pressure, etc.). Above all, the most difficult question at first is “How many Hz should I set?” However, if you have a simple vibration meter, you don’t have to worry much. This is because general vibration meters cannot perform FFT processing (they only use the time waveform without frequency setting itself and use the appropriate filtering to cut out the area that can be measured). However, FFT meters are different. If you set the frequency incorrectly, you may not be able to see the desired signal at all, and since it is a fundamental problem, it can be difficult.

 

Frequency setting (maximum frequency Fmax and sampling frequency)

 

When setting the frequency for vibration measurement, you basically set the maximum frequency (Fmax). This means the highest frequency on the horizontal axis of the spectrum graph. In the past, advanced FFT types expressed this as sampling frequency (sampling rate), which is usually twice the Fmax in vibration measuring instruments. To be exact, it is 2.56 times, but it is set to 2 times. Therefore, if you ask about the sampling frequency, you can divide the maximum frequency by 2. However, it is not important to enter the setting value, but to think in advance about, for example, 'What can I see if I set Fmax to 1000 Hz?'. See below.

 

#vibration measuring instrument, #frequency setting, #Fmax, #maximum frequency, #sampling frequency, #sampling rate, #FFT, #3-axis vibration sensor, #acceleration sensor, #vibration education, #building vibration, #vibration measurement, #resonance analysis, #resonance measurement, #vibration monitoring, #vibration noise consulting  www.kCBM.kr,   https://blog.naver.com/vs72 , https://contents.premium.naver.com/bisope/visope

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

BISOPE series 51 How to set the appropriate frequency when measuring se...

BISOPE series 51- How to set the appropriate frequency when measuring (setting the maximum frequency for vibration measurement)

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When measuring vibration using an FFT vibration measuring instrument, there are more things to consider in advance than measuring other physical quantities (temperature, displacement, pressure, etc.). Above all, the most difficult question at first is “How many Hz should I set it to?” However, if you have a simple vibration system, you don't need to worry much. This is because FFT processing is not possible in general vibration systems (the area that can be measured using only the time waveform without setting the frequency itself is cut out using appropriate filtering). However, FFT instruments are different. If you set the frequency incorrectly, you may not be able to see the desired signal at all, and it may be embarrassing because it is a basic problem.

 

​Frequency setting (maximum frequency Fmax and sampling frequency)

 

When setting the frequency for vibration measurement, you basically need to set the maximum frequency (Fmax). This means the highest frequency on the horizontal axis of the spectrum graph. In advanced FFT types of the past, this was expressed as sampling frequency (Sampling rate), which is usually twice the Fmax in vibration measuring instruments. To be exact, it is 2.56 times, but it is set at 2 times. Therefore, if you are asking about the sampling frequency, just divide the maximum frequency by 2. However, it is not important to enter the setting value, but for example, 'What can I see if I set Fmax to 1000Hz?' The most important thing is to think about it in advance. See below.

 

 

In other words, determine the maximum frequency after determining the following matters. Above all, the most basic principle is that the frequency group to be checked must be measured and placed so that it is visible in the center of the screen.

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1. Determine the specifications of the machine

 

-Rotation speed of the prime mover (drive component) (number of poles of the motor, electric frequency, number of blades of the turbine, sleeve rolling bearing, and other rotating elements)

-Sleev

​https://blog.naver.com/vs72

#Vibration measuring instrument, #frequency setting, #Fmax, #maximum frequency, #sampling frequency, #Sampling rate, #FFT, #3-axis vibration sensor, #acceleration sensor, #vibration education, #building vibration, #vibration measurement, #resonance analysis , #resonance measurement, #vibration monitoring, #vibration noise consulting

 

89 측정시 적정한 주파수의 설정방법진동측정을 위한 최대주파수 설정v2

즉, 다음의 사항을 파악한 다음 최대주파수를 정한다. 무엇보다도 가장 기본적인 원리는 확인해야 하는 주파수군이 화면의 중앙에 보이도록 측정 및 배치를 해야한다는 것이다.

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1. 기계의 제원파악

-원동기(drive component)의 회전수(모터의 pole 수, 전기주파수, 터빈의 Blade수, Sleeveor Rolling 베어링, 기타 회전요소)

-Sleeve 베어링은 저주파를 잘 측정할 수 있어야 한다.

-피동 driven component의 회전 이벤트 정보(Blade수, Vane수,Sleeve or Rolling 베어링, 기어의 단과 잇수, 기타 회전요소)

-날개통과주파수(BPF)의 3배까지 측정이 좋다.

–기어맞물림 주파수(GMF)의 3배까지 측정이 좋다.

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2. 계측기특성 및 센서의 종류 및 부착방법파악

-탐침봉일 경우 1000Hz이상 읽는 것은 신뢰할 수 없다.

-단순 자석일 경우 3000Hz이상 읽는 것은 신뢰할 수 없다.

-고주파용 센서의 경우 저주파를 잘 읽어낼 수 없다.

-계측기의 최저주파 Noise한계를 파악해야 한다.

-초저주파(3Hz이하) 측정 알고리즘을 이해하여야 한다.

-저주파는 저주파센서로 측정해야 선명하게 읽을 수 있다.

-저주파 Noise의 경우 케이블의 Noise문제도 파악한다. (케이블이 움직이면 저주파 노이즈가 증가한다.)

-Ski slope 현상을 이해한다.(적분오류로 인해 저주파를 측정