Wednesday, August 13, 2014

A Screw in a Confined Trough or Tube, Used to Move Material


http://www.clrwtr.com/ABB-ACS550-Drives.htm

A screw in a confined trough or tube, used to move material by rotating the screw. In some cases, the auger is also used for mixing and cooking.

Required Drive Features:

The drive can control multiple independent rates of acceleration and deceleration for the motor and load. These features control the amount of time the drive takes to increase or decrease the output during speed control.

Each application has specific requirements for I/O. Analog I/O is generally used to read process signals and output signals proportional to drive status. Analog I/O is generally Voltage (0-10V) or Current (0(4)-20mA). The type and number required by the application must match the drive.

Applications that involve multiple drives in a coordinated system often benefit from a common bus configuration. Drives are connected via their DC bus rather than the AC line. It allows energy to be shared between drives and reduces the number of components.

Specifies the amount of base speed that the speed reference is reduced when at full load torque. Use the droop function to cause the motor speed to decrease when an increase in load occurs. This function is normally associated with master/follower application.

Applications that require rapid deceleration or quick stops can regenerate energy back to the drive. A dynamic brake dissipates this energy through a resistor as heat.

High performance applications often demand nearly instant response to changes in speed or torque commands or input status changes. The higher the dynamic response, the more capable the drive is in meeting these demands.

Motors are rated by the manufacturer for the voltage resistance of the insulation system. If this insulation system voltage is too low, voltage reflection from the drive could cause motor failure. This is particularly important if the motor is a long distance from the drive and if the motor is an older motor being retained for the application.

Applications may require varying degrees of overload capacity for starting, accelerating, or intermittent duty. This overload capacity must be supplied by the drive as current and by the motor as torque.

A feedback device on the motor or machine, typically an encoder or resolver, feeds position information to the drive. The drive compares this information to a desired setpoint and adjusts its output to place the load in the desired position.

Applications that control a continuous process cannot afford to stop because of short power outages or dips. The process must continue to run through these outages, typically 2 to 3 cycles long.

A squirrel-cage motor slips under load. To compensate for this, the frequency can be increased as the motor torque increases.

All applications operate over a given speed range, defined as the ratio of maximum continuous speed to minimum continuous speed.

Applications that do not require significantly more torque than the original motor rating can most often be addressed by a drive using V/Hz algorithms. Loads, such as centrifugal fans and pumps or simple conveyors, are difficult to overload and therefore do not require the performance of other motor control algorithms. Simply maintaining a fixed ratio between drive output voltage and frequency is sufficient.

Applications that depend on accurate speed to accomplish the task require a drive that can control or 'regulate' speed.

Recommended Choice: ABB ACS550 Series  

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