Speed Profiling Defines Speed-Step Changes Without an External Controller

Rockwell Automation has added speed profiling, encoder/encoderless switchover and an encoderless-with-deadband option to its Allen-Bradley 1336 IMPACT AC drive. The main feature, speed profiling, allows users to define 16 speed-step changes for greater control.

Previously, drives required an external controller, such as a programmable controller, to change the speed command in a drive. The new, embedded speed profiling feature in the 1336 IMPACT drive gives users the flexibility to run applications at a specified speed based on time, encoder counters, or hardware inputs through the L-option card, saving panel space and costs associated with an external controller.

For applications requiring repeatable speed-step changes — such as turntables, hemmers, gantries, run-out tables, transfer shuttles, palletizers and station gates — the 1336 IMPACT with speed profiling can be programmed for a series of up to 16 speed-step changes. These changes are based on either an encoder pulse count, a specific time interval or by toggling a digital input in the drive. The sequence of the profile can be a single cycle with a ‘return-to-home’ or a continuous loop with a ‘return-to step-1’ routine. For added flexibility, each speed step has three parameters for configuration, including the step RPM speed, units of travel and the type of index or move needed to perform.

With its patented Force Technology – a field-oriented control technology developed by Rockwell Automation that permits independent control of speed and torque — the Allen-Bradley 1336 IMPACT AC drive provides speed and torque control of standard AC induction motors. Speed profiling brings the added flexibility of defining speed-step changes to demanding motor control applications.

The encoder/encoderless switchover function automatically switches from encoder feedback to encoderless operation without faulting the drive. This is accomplished by running the drive in encoderless mode and using the process trim loop as an outer speed trim loop. This feature is intended for continuous casters and similar applications.

The encoderless-with-deadband option is effective when the drive is operating below 1 hertz in encoderless mode. For low-speed applications, such as extruders, this eliminates cogging at low speeds by generating a zero-speed command while operating below 1 hertz.

More information can be found at www.automation.rockwell.com