Siemens SITRANS WW310, Operating Instructions Manual

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SITRANS WW310
Operating Instructions, 03/2014, A5E33490433-AA
11
Operation
4
4.1 Weighfeeders
Weighfeeders weigh bulk material while it is conveyed. An accurate rate of flow and totalized
weight measurement is received without interrupting the flow of material in process. A
weighfeeder can also control the rate of flow of the conveyed product.
In-motion weighing requires accurate transmission of the product load to load cells. The resulting
voltage signal corresponding to weight is transmitted to the integrator and becomes one of the
two inputs required for integration.
Unlike static weighing, in-motion weighing integration requires a second input: a pulse signal
proportional to the speed of the conveyor belt. Each belt speed sensor pulse represents a fixed
distance of belt travel.
Since the force measured by the load cell is represented as weight per unit length, it can be
multiplied by the distance of belt travel (one speed sensor pulse) to provide product weight for
that segment of the belt (lbs/ft x ft = lbs, or kg/m x m = kg).
Adding the samples provides total throughput weight of product across the scale. With proper
scaling and calibration, the total weight can be displayed in kilograms, pounds, short tons, long
tons, metric tons, or other appropriate units.