Variable Frequency AC Motor Drives

THAYER SCALE uses a number of different Variable Frequency Controllers to match a particular applications unique requirement. For general application Thayer Scale will use either Allen Bradely Power Flex 40© or SEW Movitrac© LTE-B. Should a customer standardize on a particular manufacturer of controller Thayer Scale will try and use that brand as long as it meeds our standards for control and accuracy.



Variable frequency ac motor drive systems.


Suitable for applications up to 7.5 kW, the PowerFlex 40 features sensorless vector control to meet low end torque demands, which helps improve application performance and maintains uptime. With an uncomplicated programming structure the PowerFlex 40 can be quickly and easily installed and configured for a variety of applications.

Optimized Performance and Functionality

PowerFlex 40 uses sensorless vector control for power motor torque at low speeds making it ideal for applications such as Weigh Belt or Loss-In-Weight Feeders. The PowerFlex 40 is also equipped with highly configurable I/O including the ability to perform basic logic, timer and counter functions.

Simplified Installation and Configuration

To simplify programming, the PowerFlex 40 has an integral keypad with 10 most commonly programmed parameters grouped together for fast and easy start up. If PC programming is preferred, the drive’s RS 485 communications can be used along with Allen-Bradley Drive Explorer and Drive Executive configuration and monitoring software. The PowerFlex 40 is also designed to accommodate internally mounted communication option cards, such as DeviceNet, making it an ideal choice for applications requiring advanced networking capability.

Operator Interface:

Integral keypad with a 4 digit display, 10 additional LED indicators and local potentiometer.

Input Specification:

  • 1 phase Voltage: 100-120V / 200 -240V.
  • 3 Phase Voltage: 200-240V / 380 – 480V.
  • Frequency: 47 to 63 Hz.
  • Frequency Range: 0-400Hz.


  • 24V sink or Source control
  • 3 dedicated inputs for start, stop and reverse
  • 4 programmable inputs for functions such as preset speeds, jog, etc
  • ± 10V (bipolar), 0 – 10V and 4 – 20 mA input control signals
  • 1 programmable form C relay output
  • 1 analog output (0 – 10V or 4 – 20 mA)
    2 programmable opto outputs


The range of functions provided by MOVITRAC® LTE B is particularly well adapted to simple applications. Its user-friendly design makes integration quick and easy. At the same time, it also meets the high quality requirements of SEW-EURODRIVE as a matter of course.

The MOVITRAC® LTE B is available in three sizes for power ranges from 0.37 to 7.5 kW and supply voltages of 115 V, 230 V and 400 V.

In addition to the standard version in degree of protection IP20 for installation in the control cabinet, there is also a version in degree of protection IP55 / NEMA 12 and IP66 / NEMA4X, to be used under specific environmental conditions.

Technical data:

Mains connection Power range

  • 115 V / 1-phase 0.37 to 1.1 kW
  • 230 V / 1-phase 0.37 to 2.2 kW
  • 230 V / 3-phase 0.37 to 4.0 kW
  • 400 V / 3-phase 0.75 to 7.5 kW (IP20 up to 11 kW)

40 configurable parameters

  • Degree of protection: IP20 / NEMA 1 (control cabinet)
  • Degree of protection: IP55 / NEMA 12 for field applications
  • Degree of protection: IP66 / NEMA 4X for field applications
  • Integrated operating device for simple operation

Variable frequency ac motor drive systems.