In a previous post I discussed electric motor testing, specifically static or offline testing. This week I would like to tackle the subject of dynamic or online testing of electric motors. As the name suggests, dynamic tests are performed while the electric motor is running i.e. when it…
read moreMachines are expected to vibrate as little as possible to avoid component fatigue/failure and in some cases, reduce user comfort level, for example, violent vibration of an automobile can lead to mechanical failure and driver discomfort. There are ways to avoid violent vibration such as…
read moreElectric motors are a key component for running machines in most industrial environments. Therefore it is important that they are properly monitored to avoid unwanted failures or shutdowns. Typically, there are two testing categories for electric motors: 1. Static or offline tests 2. Dynamic or…
read moreSome boats vibrate more and make a lot of noise. Vibration and noise in boat require immediate attention. Vibration and noise are related; vibration generates unwanted noise. Below are some ways to decrease vibration and noise on your boat: Boat PropellersOne of the most common…
read moreAliasing is a phenomenon that can occur due to improper sampling or data collection, where the original signal is indistinguishable when reconstructing data from the collected samples. This usually occurs because the sampling rate and/or resolution is inadequate. Figure 1 shows an example of aliasing. The original…
read moreThere are two vibration situations in which statistical analysis is useful. The first situation occurs when the vibration amplitude of a system appears to be random in time. In this case, it is convenient to describe the response of the system statistically. This form of…
read moreThe crest factor is also referred to as the peak-to-average ratio, or the the peak-to-average power ratio, for a waveform. It is the ratio between the peak amplitude of a waveform and the RMS value, as shown in the following equation: C = Peak amplitude RMS…
read moreDampers have been widely used to reduce the amplitude of vibration by absorbing or dissipating energy. In general, damping can be divided into three types: viscous damping, column or friction damping, and solid (internal) or structural damping. We will focus on viscous damping in this…
read moreA coupling is a mechanical device or hub used to connect two shafts to transmit power from drive end, for example: motor, to driven end, for example: pump or fan. Other purposes are to protect overloads and to provide mechanical flexibility due to misalignment. They…
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