Vector math is often seen as an overcomplicated and daunting task. You may think that it is useless because your vibration data collector does this math for you and will just tell you where to make corrections, but the reality is that you will be a better balancer if you understand the process. This blog post will break it down and make it simpler to understand.
Understanding Circular Plot Graphs
A circular plot is a graph showing amplitude and phase.
Phase is shown as the position on the circle in degrees, and amplitude is shown as the distance from the center of the circle.
When we begin a fan balance, we need to get what is referred to as a “reference run,” which is a plot of both the phase and amplitude of vibration that is present on the fan before we make any changes. The data will be presented as a single dot as shown below.
Here, the data collected is shown as a single orange dot. If the amplitude scale is 1 mil per segment, the amplitude would be 5 mils, and the phase, represented by its position on the circle, would be right at 90 degrees in this example.
Balancing with Trial Weight
The next step in the process of balancing is to apply a “trial weight”. The idea here is to create a change in amplitude and/or phase. Here we apply what is referred to as the 30/30 rule. The 30/30 rule states that we need to achieve a change in amplitude of at least 30% and/or a 30-degree change in phase.
You will see that in the next image as an example.
The blue dot in the image above will represent the reading after applying the trial weight. At this point, we have enough information to make our correction.
Manual Plotting and Math
Let’s walk through the math…
If we had done this manually, the fuchsia-colored arrow would have been drawn on the plot. Then, we would get out a protractor to measure the angle and a ruler to measure the length. Using the formula (Length/Amplitude), we will get a number that can be expressed as Grams/Inches.
With that information, we will impose the angle and length of the fuchsia arrow on the orange dot, which was the original run or “reference run”. You can see that I did that here by adding the green arrow.
To keep the chart simple, I removed the trial run information.
The next step is to draw a line from the end of the green arrow to the center of the plot. At this point, we can measure the angle and length of the orange line.
We take the angle and length of the orange line and flip it 180 degrees to draw our red line and establish the point at which we need to place our correction weight and how much weight we need to apply.
By measuring the length of the line and using our values from earlier, as far as grams/inch or whatever the units may be, we can determine the amount of weight needed to make the correction.
This is the math that is taking place inside your data collector. By understanding this concept, you will have a better understanding of the balance process and be more capable of identifying errors before they occur.
Understanding the math behind the balancing process empowers you to spot issues early, but you don’t have to do it alone. The Acoem Wireless Balancer handles the calculations for you, streamlining the process while still giving you complete visibility and control. It’s precision balancing, made simple.
