As I delve into learning about industrial automation processes, I am eager to understand the functioning of a weight feeder unit. This unit comprises a load cell and speed sensor linked to a PLC that manages the VFD for motor speed regulation. Can you shed light on the calculation involved in integrating the signals from the load cell and speed sensor to effectively control the VFD? Thank you for your assistance.
The necessity and utility of a motor speed signal in a feeding system for dry bulk solids, such as an auger-type system, is questionable. I have experience designing bulk solids dosing systems that utilize a knife gate instead of an auger, eliminating the need for a speed signal. The flow rate in such systems varies based on factors like product quantity in the hopper, granule size, coefficient of friction, and bulk density. Initially, I attempted to implement the Beverloo equation into my dosing system algorithm, but found it overly complex and ineffective. Simplifying the algorithm was the key to successfully dispensing various products without prior knowledge of their properties. The process involved opening the valve rapidly until one-third of the target weight is reached, then maintaining the position until halfway to the target weight. Subsequently, the valve is closed gradually to achieve the final target weight, with adjustments made based on weight feedback. In a system like the one described, where weight is the primary feedback mechanism, the speed of the auger motor seems unnecessary. If I were to design an auger-based system, I would adopt a similar approach but with even fewer steps. Running the auger at full speed until reaching 95% of the target weight, then gradually reducing to a dribble before reaching 100%. In practical applications, especially for precise dosing, a "dribble mode" at the end is crucial to account for fluctuations in load cell readings as the weight changes. In instances requiring extreme accuracy, it may be beneficial to stop completely before reaching 100%, average the weight for a few seconds, calculate the necessary rotations to reach 99%, perform the rotations, average again, and then adjust accordingly to reach the target weight precisely.
If you are interested in understanding the functionality of a weight feeder unit incorporating a load cell and speed sensor linked to a PLC for motor speed control, then Frozzxx's explanation is essential. This setup is crucial in industries where precise measurements are necessary for efficiency and accuracy. For batch filling operations, following @strantor's method would be suitable. However, for continuous processes involving a "check weigher" or "in-motion scale," a distinct strategy would be needed to ensure optimal performance and productivity.
I have visited several industrial sites where bulk silos were used to supply materials for a continuous manufacturing process. We employed loss in weight measurement to determine the flow rate, which was monitored and adjusted every minute to regulate the speed of the auger. Typically, we had 2 to 3 silos in operation simultaneously. While the process was not extremely precise, it effectively prevented any overflow on the feeder belt. The feeder belt was equipped with load cells and adjusted its speed to achieve a more accurate flow rate for the manufacturing process. As an illustration, let's consider 2 silos operating at a rate of 25 tons per hour each, feeding a belt set at a sepoint of 50 tons per hour.
The poster is discussing a gravimetric feeder system, which is more intricate than simply dumping materials onto a conveyor with load cells. If you have a feeder system of this type, it is crucial to have a thorough understanding of the mechanical engineering principles involved before delving into control equations. I have experience working with various feeder systems, and it is important to note that they are all unique in their operation. As you aim for more precise feed controls, the number of variables to consider increases, which in turn requires accurate monitoring of additional sensors.
padees noted that the original poster (OP) is discussing a Gravimetric feeder system. Are you referring to a continuous Gravimetric feeder system?
It sounds like you're diving into a fascinating area of automation! To effectively control the VFD using data from the load cell and speed sensor, you would typically calculate the desired flow rate based on the combined information. First, you would determine the weight of material being fed by the load cell (in units like kg or lbs) over a specific time frame, giving you flow rate. Meanwhile, the speed sensor provides feedback on how fast the feeder is moving. By integrating these two signals, you can adjust the speed of the VFD to maintain a constant flow rate based on the desired setpoint. Essentially, it's about fine-tuning the motor's speed in response to the real-time weight and speed data to achieve optimal process control. Keep experimenting and good luck with your learning!
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Answer: - A weight feeder unit typically consists of a load cell, a speed sensor, a PLC (Programmable Logic Controller), and a VFD (Variable Frequency Drive) for motor speed regulation.
Answer: - The signals from the load cell and speed sensor are processed by the PLC to calculate the required motor speed adjustments for accurate material feeding. The PLC uses algorithms to determine the appropriate motor speed based on the weight measurements and material flow rate information provided by the sensors.
Answer: - The PLC acts as the control center in a weight feeder system, receiving signals from the load cell and speed sensor, processing the data, and sending commands to the VFD to adjust the motor speed accordingly. It ensures precise control over material feeding processes.
Answer: - By accurately measuring and controlling the material flow rate, a weight feeder unit improves efficiency, consistency, and accuracy in industrial automation processes. It helps in optimizing production, reducing waste, and ensuring product quality.
Answer: - Yes, the PLC utilizes mathematical calculations and algorithms to process the signals from the load cell and speed sensor,
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