High-Precision Weighing Even in Difficult Plant Environments

Consider a loss-in-weight feeder operating in a typical plant environment. Feed rate control is achieved by continuously weighing the entire feeding system, then controlling the rate at which the system loses weight. In the above plot of feeder system weight vs time, the desired feed rate is represented as the change in system weight per unit time, or simply the slope of the setpoint line. The unknown load applied to the weighing system is a composite of the actual system weight plus the variable force contributed by in-plant vibration

Applied load... (A) causes wire (B) to change its resonant frequency (10-15KHz measurement range). Waveform (C) is converted to a square wave (D) For example, with 10,000,000 clock pulses per second, up to 10 waveform groups consisting of 1,000 or more waves per group can be timed to a measurement resolution of at least 1:1,000,000.

 Weight Feeder Scales and Load Cell Catalog

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