DN Staff

August 7, 2000

4 Min Read
Hot products

Drive has 16 speed steps

By adding speed profiling, encoder/encoderless switchover, and an encoderless-with-deadband options to its Allen-Bradley 1336 IMPACT ac drive, Rockwell Automation's focus is clearly on full function smart drives. Speed profiling augments the drive's patented Force Technology(TM)-a field-oriented control technology that permits independent control of speed and torque-with 16 defined speed step changes for greater control in applications such as turntables, hemmers, gantries, run-out tables, transfer shuttles, palletizers, and station gates. "Previously, drives required an external controller to change the speed command in a drive," says Senior Product Marketing Specialist Lynn Cooksey. "Embedded speed profiling gives users the flexibility to run applications at different speeds. The encoder/encoderless switchover function automatically switches from encoder feedback to encoderless operation without faulting the drive. The encoderless-with-deadband option is effective when the drive is operating below 1 Hz in encoderless mode. "In low-speed applications such as extruders," explains Cooksey. "It eliminates cogging by generating a zero-speed command while operating below 1 Hz."

Drive cleans line harmonics

While electric utilities deliver relatively clean power in the form of pure sinusoidal waveforms, a facility's nonlinear loads such as computers, drives, and electronic ballasts can introduce undesirable harmonic currents onto the power system. That's why many facilities demand that the IEEE 519-1992 standard for minimizing harmonic distortion be met in order to eliminate the potential for equipment failures which lead to increased downtime and added costs. Targeted at applications in the water, wastewater, HVAC, industrial, and process industries where harmonics are a concern, Cutler- Hammer's CP9000 uses an 18-pulse rectifier and a specially designed transformer that work together to phase-shift out harmonic distortions. "With deregulation, utilities are more critical about how facilities effect the power supply," explains Product Manager Dave Heidel. "We see more industrial applications where the facility has a high volume of electronic drives and computer equipment that they don't want to damage. Our clean power technology significantly reduces line harmonics at the drive input terminals resulting in one of the purest sinusoidal waveforms available."

Mini module is sealed tight

Designed for operating fractional and integral horsepower motors, the CMI-5015-48 motor control module comes in a hermetically sealed package. "Compact size and performance are its key benefits," says Tim Hickey VP of sales and marketing at Composite Modules Inc. Extra consideration in transistor mounting improves thermal performance. The self-contained package includes all the bypass capacitors typically required to control 3-phase dc brushless motors. "And a unique low loss current sensing circuit and internal bus capacitor eliminates the need for large external components," says Hickey. "All you need to make it run is a single 22 to 48V power supply, a 0-5V signal for speed control, and signal for reverse or forward direction," he explains. Three 15V CMOS compatible open collector hall devices are required for commutation. By using a custom high-side driver to operate the high-efficiency "N" Channel MOSFET output stage, Hickey explains, "the design achieves true low to zero speed operation without the loss of the high-side voltages." The 3 x 2 x 0.375 inch motor-control driver includes an internal reference that allows the module to operate off a single supply as low as 16V while supplying maximum current to the output stage.

Drives have three inertia levels

Aromat Corp.'s newest line of ac servo systems, manufactured by Panasonic, provides accurate positioning, full-close control with built-in encoder (17-bit absolute encoder option), Windows compatible software, UL, CE, C, EC approval, and IP65 rating. According to Gustavo Vargas PLC specialist and technical support supervisor, the A Series has the ability to control three different types of signals: analog, digital, and pulse and direction inputs. "All three modes can be combined in a single application with the drive switching from torque control to positioning control for example." The servo lines offer three types of motor inertia levels: low inertia (30W-5kW) for applications such as positioning, IC mounting, and wafer handling devices; middle inertia (300W-5kW) for applications such as CNC, robotic arms, and conveyor systems; and high inertia (400W-5kW) for heavy-duty applications such as woodwork and specialized CNC machines. One of the biggest advantages is the way the motor was designed according to Vargas. "By replacing the traditional single piece core design with a 12-segment core, we get more torque out of a smaller package." With RS-232 and RS-485 communication ports, up to 16 servos can be linked. The ac servo drives are targeted at space-constrained applications in multi-axis control, pick and place, winding, speed, and tension control.

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