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Additive Feeders Chapter 4: Operation 33 of 55
Example 1: An extruder rotating at 30 RPM and providing 8 pulses per revolution generates
240 pulses per minute will provide excellent results.
Example 2: An extruder rotating at 15 RPM and providing 1 pulse per revolution generates
15 pulses per minute and will provide poor results.
Maximum Input Pulse Rate
As programmed, the drive is capable of accurately following an extruder’s rate signal of up to
50,000 pulses per minute. Extruders that provide rate signals above this frequency
REQUIRE end user programming to provide accurate results. The value programmed into
parameter P16 must be modified to a value that filters this pulse rate to an acceptable
frequency. Please refer to the parameter description section for additional information.
Example 1: An extruder rotating at 175 RPM and providing 8 pulses per revolution
generates 1,400 pulses per minute will provide excellent results.
Example 2: An extruder rotating at 250 RPM and providing 250 pulses per revolution
generates 62,500 pulses per minute and will provide poor results.
Minimum and Maximum Percent Setpoints
The drive rotates the additive feeder’s auger at a constant percentage of the extruder screw. If
the extruder screw is turning at 100 RPM and the setpoint is 50%, the additive feeder turns at
50 RPM. Increasing the extruder speed to 110 RPM will make the additive feeder rotate at
55 RPM. Decreasing the extruder speed to 90 RPM will make the additive feeder rotate at 45
RPM.
As programmed, the drive accepts percentage setpoints from 10% to 200% of the extruder’s
speed. The drive and motor’s acceptable operating speed range is 3 to 71 RPM.
Increasing the percent setpoint to a value that would cause the auger to rotate over 71 RPM
will NOT cause the feeder’s auger to rotate OVER 71 RPM.
Example 1: The extruder is rotating at 75 RPM, and the additive feeder percent setpoint is
85%. The additive feeder’s auger will rotate at 63.75 RPM.
Example 2: The same extruder’s speed setpoint is increased to 100 RPM without changing
the additive feeder percent setpoint of 85%. The additive feeder will rotate at its maximum
speed of 71 RPM, not at 85 RPM. If your application requires that additives be fed at a
higher rate than what71 RPM provides the simplest method is to increase the size of the
auger and sleeve your additive feeder is equipped with. Please refer to the parts section for a
complete listing of available sizes.
The minimum and maximum percent setpoints may be custom programmed to more precisely
reflect the range of speeds in use at your facility. Please refer to the parameter description
section for additional information.