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Turbine Balancer

Turbine Wheel Balance

Turbine Wheel Balance

Price: 322.00


The balancer works with the aid of Piezo transducers and operates on 12 voltssmooth DC input. It works on any size wheel of micro turbines.

How does the Balancer work? Taken from the Internet...for Ref only

Each rotating mass will cause a centrifugal force, pointing away from its rotational axis. In the ideal case that every “mass segment” is countered by an equal mass on the other side of the rotational axis, there will be no resulting force (except gravitation) that needs to be carried by the shaft or the bearings during steady rotation.

But due to manufacturing tolerances or uneven distribution of alloy components during casting, all rotating components will reveal a more or less severe degree of imbalance. This will cause a “vibrating” force exerted to the bearings of the rotor and hence can be measured by force- or translation-transducers attached to the bearings.

As a typical translation-transducer a magnetic transducer will require significant movement to generate a reasonable output voltage, thus demanding for a “soft” suspension with the accompanying low resonant frequency, well in the range of rotational speeds. So I didn’t choose one of these in my balancer design.

A piezoelectric transducer measures force and is a very “stiff” device, and by arranging two in a push-pull arrangement the elastic constant will still be increased. The problem is that these transducers can be considered from the electrical point of view as a variable voltage source (depending on the applied force) in series with a capacitor (depending on the material properties and the size). In conjunction with the following high-impedance buffer's input resistance this will form a high-pass filter with a characteristic time constant (T=R*C). Only if the period of the rotational frequency is well above this time constant the output signal will be in phase with the force applied to the transducers. But the time constant achievable in my balancing setup will be around 1s, thus all balancing RPMs above about 500/min will be fine.

Now arises the question: How is the position and amount of imbalance to be determined?

This purpose serves a trigger circuitry with a variable level. It is a simple voltage comparator, driving a constant current source as LED driver. The inverting input of the comparator is connected to a variable voltage source while the noninverting is fed with the output of the transducer/buffer assembly.

If this "imbalance signal" increases above the trigger level momentarily the LED will be lit.

The trigger level will then be set to a value that only the most positive part of the imbalance waveform will exceed the trigger level. If the LED is pointed to the wheel to be balanced, this seems to be standing still (stroboscopic effect). If there has been a mark placed on it before (or has already been present), you can stop the wheel and place it statically in the position that has been spotted with the LED.

In this position the "heavy side" of the wheel will point directly to the transducer that causes the LED to light when pushed on (the "+" transducer).

Now a counterweight will be attached to the other side of the wheel (usually I use textile adhesive tape) and the balance re-checked. During this process the trigger level will have to be set lower each time, as the imbalance decreases. When the vibration caused by imbalance approaches the noise level generated by the bearings, it becomes difficult to find a trigger level setting that will give a "standing" wheel display, then I usually stop and grind some material off the wheel at the side opposite from the counterweight. After that I remove all the tape and start over again to check if I took the right amount of material off.

This method requires some experience but it is possible to detect a difference with a piece of tape the size of 1mm², depending on the condition of the bearing surfaces of the shaft. And you'll get balancing finished in a reasonable time compared to other “homebrew” methods.