Will I break Arduino accelerometer sensor with certain type of settings

Hi everyone

I have a question on the limits of an Arduino accelerometer. The scenario is as follow:

I want to measure the out of plane acceleration of a small turbine with 3 blades. The turbine blade will be spinning at about 1495 RPM. After I did some research I came to the conclusion that the out of plane acceleration of the turbine blade will be anything lower than 25g.

Although, it makes thus logically sense that I need to buy an accelerometer (Arduino compatible) that can measure up to about 25g (+/-25g), there is a flaw in this way of thinking. This is because, if one consider the speed of the small turbine (e.g. 1495 RPM) the radial acceleration will be about 375g (Determined using some physics and knowing the the length of the turbine blade is 150mm or 0.15m). This is way above the 25g the accelerometer can handle. One can probably say that due to the fact that I am only interested in the out of plane accelerations, I do not need to worry about the radial acceleration component and still buy an accelerometer that can measure up to 25g.

The problem I have with the above argument is that you get certain accelerometer characteristics like cross axis sensitivity that might affect your readings drastically if exposed to an acceleration way above its limits. In any case, it is a risk to expose an accelerometer to accelerations past its limits since any type of reading might be inaccurate and you don't really have a way of knowing this. You may even damage or break the accelerometer.

This then lead me to the conclusion that I need an accelerometer that can handle accelerations up to about 400g. I thus bought the Sparkfun H3LIS331DL since it has a limit of up to 400g (+/-400g). The accelerometer is also a triple axis accelerometer which gives me some extra measuring capabilities.

Below is a link to the accelerometer.

https://learn.sparkfun.com/tutorials/h3lis331dl-accelerometer-breakout-hookup-guide

Now this accelerometer can measure either between +/-100g, +/-200g and +/-400g if you specify the correct settings in your Arduino code. Naturally, the smaller range setting one uses, the better resolution one gets. Now in my case, I would prefer having the best (smallest) resolution possible. Thus +/-100g.

Hence my question is whether it will be okay if I use the setting +/-100g since I am really only interested in accelerations below 25g? This is different from the previous scenario since I know that my accelerometer can handle up to 400g. Does the setting I use in the Arduino code for the accelerometer have any affect on the its limits? Hence will the +/-100g setting break or damage the accelerometer since one of axes will be experiencing an acceleration way above 100g or will this high acceleration (375g) just be clipped to 100g and not have an effect on the accelerometer itself (damage or break it).

I apologize for this long explanation, but I sincerely hope someone can clarify this issue for me. I unfortunately do not have enough knowledge on accelerometers and particularly Arduino accelerometers to definitively answer this question.

The more interesting question is: How do you make sure the turbine is not affected by your PCB?

The better (and easier) way to handle things like that is to add sensors to the bearings of the blades and do the maths correctly. You might want to get a look at the devices used to balance car tires.

Hi Zwieblum

Thanks for your quick reply. I don't have to worry about how the turbine is affected by my PCB. If I have to explain why it will take few pages. I am really only interested in what will happen with my accelerometer accelerometer as explained previously.

Ok. It'll work, but make sure you are inside the specified g-limits for all components - if not, get creative with the PCB layout (lower g near the axis). And take care of the PCB basematerial - it could tear.