For order tracking, we need analog channels to measure vibration, noise, pressure or other parameters from which we would like to extract the orders. Additionally, we need the sensor for measuring rotation speed of the machine, either an encoder or a tacho probe. It is recommended that we use Orion counters for calculating the RPM or, for tacho, to simply acquire an analog signal. Then we need to make sure that the sample rate is high enough to see the triggers, even at the maximum speed. Please note that we also need to use internal sampling for the correct calculation of the order tracking.

In this case we have one accelerometer for measuring the vibration and one encoder for measuring RPM. First we set up the vibration channel. We enter the Unit of measurement in g and the Sensitivity of the sensor as 96 mV/g from the calibration paper of the sensor. Next, we select the measurement Range .

Order tracking channel setup

The following step is adding one Order tracking math module and selecting the source of the frequency measurement. We can select any counter sensor. If we choose the encoder, we need to connect the encoder to the counter input. Please note that only Orion counters can be used in this scenario. If we have a tacho sensor (or any other analog sensor for that matter), then we need to connect the sensor to the analog input and define the trigger levels by clicking the Setup button, which appears to the right of the Frequency channel settings.

Next we define the Lower RPM limit, Upper RPM limit and Delta RPM. These three parameters are important for reserving memory of waterfall FFT based on the order tracking. In this example we expect the RPM to be in the limits of a 0 to 3000 RPM range and we want to have an FFT each 50 RPM. This will give us the (3000-0) / 50=60 frequency spectrums over defined RPM range. We can also define the Direction of triggering either to capture only run-up, coast-down or both. Additionally we can define Delta time interval. If the RPMs are not changing, we can define the Maximum time limit for calculating the harmonic point. It will calculate a new point in the run up diagram after this time interval to be able to see the deviation of amplitudes at the same speed. In this section we also define the time Update criteria for calculation. Always means that the data will be acquired any time the frequency range is passed, while Only first time means that the data will be acquired only the first time that the frequency range is entered and not subsequently .

Then we define the Order setup. For the calculation of the frequency history spectrum we define the order resolution, maximum order and FFT window. FFT window is the window used for the calculation of the FFT spectrum. Since the data captured is angle based, we can also use "soft" windows like Hanning if only a harmonic component is seen in the signal. If we have many non-harmonic components, then it is recommended to use a window like Blackman. The maximum order defines the order span of the frequency spectrums. When the data is recalculated, it is filtered to this maximum order. Also the result of the frequency spectrum will be limited to this order in Order OT mode. This number depends on the maximum excitation frequency we expect. The order resolution defines what the steps will be in the frequency spectrum. If we want to see the natural frequencies nicely, it is recommended to use a 0.125 order.

Next we need to define the Extracted harmonics . We can enter a list (like 1;3;8;12) or define to extract All orders. This will create the channel for each order defined in the order setup, so with our setup we would have 512 channels (8*64=512), which is hard to handle. Thus, it is recommended to extract only the orders that are actually interesting. We can extract the amplitudes, the real and imaginary parts and the phase of each harmonic.

Order tracking setup