A shaft power calculator is an instrument that calculates the propeller output power by measuring the shaft torque and rotational speed. The most common use of this instrument is found in ships, and thanks to them, the ships can have output power control. Usually, these systems are installed into a ship during the very process of its construction.
To calculate the torque inside the propeller shaft, you’ll need to grade the surface strain. The strain is caused by the twisting of the shaft since the torque forces that come from the inside are proportional to it. For the purpose of measuring the speed, the shaft power calculator has a magnetic pick-up and toothed ring that is installed near the shaft. This ring generates pulse train which frequency is on a parallel level with the speed of the rotation. At the moment, shaft power calculators use a computer and data system to complete this task with the highest precision possible.
Shaft power calculators consist of the following parts.
The calculation of the torque is done by using the strain gauges that come from the propeller shaft. After that, the signal is amplified and converted into a frequency signal. The adjustment of the shaft calculator and the offset ranges is done by the multi-turn potentiometers. Afterwards, the signal is amplified and modulated and used as an RF carrier signal, which is later delivered to an aerial. The rotor unit generally uses analogue components.
This is the part that demodulates the torque signal, which is performed inside the primary coil, aided by the power driver. The shaft speed is measured by the magnetic sensors and activated by the ring of the teeth inside the rotor unit.
Data Signal Processing Unit
This part of the shaft consists of computer parts and commercial data acquisition card. This is where the signal is converted from analogue to digital format and transferred through the compatible interface for calculation. Afterwards, the data is transferred to another port and displayed on the monitor.
With the advancement of technology, the shaft power calculator has become more simplified and easy to use. This was achieved thanks to the introduction of the micro-controlling component and because of this there is reduced cost and less manufacturing time. Also, the simplified process lowers the commissioning cost and reduces the maintenance expenses of the company.
Thanks to the shaft power, calculators power inputs are now safer and more controlled. Even though this is a complex system, it is user-friendly and engineers can use it right away without getting any special training.