Why the 1336 PLUS II Remains a Reliable Workhorse in AC Drive Technology

The Allen-Bradley 1336 PLUS II AC drive series offers a complete line of compact, high-performance Variable Frequency Drives (VFDs) that are renowned as a highly dependable AC drive technology in a variety of industrial applications, even after being officially discontinued several years ago. Available in power ratings ranging from 0.5 to 600 horsepower (0.37 to 448 kW) and three voltage ranges: 200 to 240V AC, 380 to 480V AC, and 500 to 600V AC, these drives help provide a single motor speed control solution for different application requirements and motor sizes. This article examines why the 1336 PLUS II drive series continues to be a preferred motion control solution for various industrial applications despite its obsolete status.

1336 PLUS II Overview

The Allen-Bradley 1336 PLUS II drives are essentially microprocessor-based, high-performance PWM (Pulse Width Modulation) AC drives that are designed to provide precise motor speed and torque control using Sensorless Vector Control (SVC) and/or selectable Volts-per-Hertz (V/Hz) motor control algorithms. They are well suited for industrial applications requiring highly accurate motor torque and speed control, including conveyor belts, fans, pumping systems, processing equipment, and machine tools.

Key Features

Discussed below are the key features of the 1336 PLUS II AC drive series that continue to make it a reliable workhorse in AC drive technology

Advanced and Robust Motor Control Capabilities

1336 PLUS II AC drives are equipped with powerful motor control algorithms that provide unparalleled performance. These include:

• A Fully Programmable V/Hz Control: Volts-per-Hertz control mode provides a reliable and straightforward means of controlling motor speed by maintaining a constant voltage-to-frequency ratio across a range of operating parameters. It also allows optimal performance for applications requiring several motors on a single 1336 PLUS II AC drive, especially if the connected motors are of different types and sizes: For example, a 5 HP/ 3.7 kW and 15 HP/11 kW AC motor on a 20 HP (15 kW) 1336 PLUS II drive.
• Sensorless Vector Control: This is an adaptive motor control technology that enables the 1336 PLUS II drives to deliver constant torque under varying load conditions. It provides exceptional performance enhancements, including:
• Running torque and starting acceleration in excess of 250 %
• A 120:1 constant-torque speed range that allows the 1336 PLUS II drives to handle low-speed, high-torque applications that other AC drives can’t handle
• A fast acceleration mode: SVC makes it possible to achieve the lowest possible drive acceleration time, ideal for low-inertia applications
• A programmable fast flux build-up mode that assists in the rapid acceleration of large motors
• Adaptive Current Limit feature that facilitates real-time tuning of the drive’s response
• Accurate speed control without the need for feedback devices, thereby reducing wiring complexity

The performance enhancements the Sensorless Vector Control mode provides enable the 1336 PLUS II AC drives to be particularly useful in demanding applications like large conveyors, pumps, and machine spindles, where low-speed, high-torque operation and dynamic response are crucial.

Versatile Communication Options

1336 PLUS II AC drives support a variety of communication protocols that enable seamless integration with contemporary control systems. The drives are available with the following factory-installed communication options:

• RS-422/485/232, DH485 or DF1-protocol, serial communication options
• Single point Remote I/O (RIO)
• DeviceNet
• SCANport connectivity for DeviceNet and Flex I/O

The 1336 PLUS II serial communication options are entirely compatible with all Allen-Bradley SLC and PLC controllers. They provide streamlined integration and access to peripheral equipment. All peripheral control connections to the Allen-Bradley 1336 PLUS II drives are made via SCANport, a multifaceted communication bus.

Extensive Power Ratings and Voltage Options

The 1336 PLUS II drive series provides an extensive range of power ratings from 0.5 to 600 HP (0.37 to 448 kW) in three voltage ranges: 200 to 240V AC, 380 to 480V AC, and 500 to 600V AC. This meets the motion control demands of small-scale and heavy-duty industrial motors. The series also features wide voltage compatibility, which allows seamless integration of the 1336 PLUS II drives into a variety of power systems. This makes it a versatile choice for a broad spectrum of industrial applications.

Advanced Design Simplicity

1336 PLUS II AC drives feature an advanced design that provides remarkable reliability when controlling three-phase motors. The design simplicity of these AC drives is evident in:

• Compact Packaging: Allows for easy wiring, mounting, and installationof1336 PLUS II AC drives in all types of industrial applications.
• Commonality of system design across the available power ratings
• Ease of Setup: The drives feature an intuitive parameter organization that facilitates simplified drive programming and configuration, as the drive parameters can be quickly accessed.
• Simple Tuning: The output of a 1336 PLUS II AC drive can be readily tuned to provide optimum torque performance for practically any load condition.
• An Easy-to-Read Liquid Crystal Supertwist Display: This feature is located on the1336 PLUS II Human Interface Module. It provides two lines of 8 text characters (programmable) and eight value characters (display), a total of 16 characters on each line, facilitating easy drive programming and monitoring.
• Identical device communications and control interface functions across the 1336 PLUS II drive series.

Robust Diagnostic and Protective Features

The Allen-Bradley 1336 PLUS II drive series is engineered to provide exceptional performance and includes robust safety and protective features to withstand harsh industrial environments. Key safety enhancements include:

• Real-time Monitoring: 1336 PLUS II drives can monitor crucial drive parameters in real time, including control conditions and output current. This monitoring capability allows the drive system to detect anomalies promptly, addressing problems like current surges and unanticipated control deviations before they escalate. Real-time monitoring not only protects the drive but also the connected motors and other system components, preventing costly downtime and potential equipment damage.
• Overcurrent, Overvoltage, and Stall Protection: Overcurrent protection prevents damaging current levels from impacting the drive’s electronics, whilst overvoltage protection mitigates the risk of voltage spikes damaging sensitive drive system components. Additionally, stall protection ensures a quick shutdown in the event of a motor stall, preventing overheating or mechanical stress, which could lead to drive system failure. Together, these protective measures provide an extensive barrier against electrical and mechanical anomalies.
• Plain-Language Diagnostic Messages for Fault Isolation: 1336 PLUS II drives include a diagnostic system that delivers fault messages in plain, easy-to-understand language, enhancing the ease of drive troubleshooting and maintenance. This user-friendly diagnostic interface enables technicians to quickly identify and isolate drive problems, significantly reducing the duration of troubleshooting. Also, the clarity of the provided diagnostic messages helps reduce potential downtime by enabling maintenance personnel to speedily restore a faulty drive system to operational status.

Inbuilt Advanced Special Features

• Auto-Tuning: The 1336 PLUS II Auto-Tuning feature helps streamline drive setup by automatically adjusting control parameters to fit the load characteristics of the connected motor. This self-calibration technique reduces the need for manual adjustments while providing optimal dynamic performance under fluctuating load conditions. Essentially, with this feature, the drive output is automatically tuned to deliver optimum torque performance for every load condition.
• Auto Economizer Function: The Auto Economizer mode helps optimize energy efficiency by dynamically adjusting the drive’s output based on real-time load demands. It evaluates the drive system’s instantaneous loading conditions and regulates the voltage delivered to the motor accordingly, resulting in increased energy efficiency.
• Process PI Control: The built-in Process PI (Proportional-Integral) function in 1336 PLUS II drives enables precise closed-loop process control based on the PI feedback and PI setpoint (reference). It allows for more fine-tuned adjustments to motor performance, compensating for process deviations by continuously modifying proportional and integral gains. For example, suppose the connected feedback device shows that the process being controlled is deviating from the desired setpoint. In that case, the Process PI function will respond by tuning the drive output up until the feedback equals the PI setpoint (reference) again.
• Step Logic & Traverse Functions: The Step Logic function enables1336 PLUS II drives to be programmed to execute specific logic steps, based on Digital Input, Time, Digital Input and Time, Pulse Input or Encoder Feedback Counts, and End Fault or Continuous Loop, using or without a programmable controller. The Traverse function allows the output frequency of a 1336 PLUS II drive to be programmed to vary around a specified frequency.

Conclusion

In conclusion, the Allen-Bradley 1336 PLUS II drive series’ sustained relevance in today’s industrial applications underscores its foundational engineering excellence and adaptability, with its design principles enduring far beyond its intended lifecycle. As explored in this article, its operational reliability stems from a combination of a robust but simple design, an extensive range of power ratings and input voltages, powerful motor control algorithms, advanced diagnostics, and support for versatile communication options—features that were groundbreaking in the 1990s and remain functionally adequate for many motion control applications today.

In addition, the 1336 PLUS II Sensorless Vector control mode, which delivers starting torque in the excess of 250% and precise low-speed regulation, continues to meet the demands of heavy-duty industrial applications. While its plain-language diagnostics simplify troubleshooting in legacy systems. Furthermore, its compatibility with discontinued Allen-Bradley PLC platforms (e.g., PLC-5, SLC 500) and SCANport networks has made it indispensable for facilities prioritizing operational continuity over modernization.

We at DO Supply carry the 1336 PLUS II drives as well as offer the option to repair your existing drive. We know these drives could be absolute work horses but after putting in decades of work, they might need some help. So give us a call today and find out how we can get your drives in tip top condition!