Unlocking Performance: An in-depth look at PowerFlex 7 drives

Modern VFDs have revolutionized the operation of the industrial machine as the control over AC motors’ speed and torque has become more and more accurate. Among all the top choices for state-of-the-art drives are Allen Bradley’s PowerFlex 7 series drives. These drives are known to be a superior engineering solution for demanding industrial requirements. These requirements include flexible control, superior efficiency, and a range of communication and safety features. This article provides an in-depth analysis of the technical specifications, control methods, and unique attributes of the PowerFlex architecture-class 7 series.

Key Features of PowerFlex 7 Drives

PowerFlex 7 series offers different drives, each with different methods for regulating the speed and torque of AC motors for a variety of applications. These applications are material handling, oil and gas, power generation, etc. Other than that, the drives come in a broad range of voltages and power, control options, safety features, and predictive diagnostics to cater to all these requirements.

Electrical Specifications

• Voltage Range: The Powerflex 7 series supports a voltage range between 200 VAC and 690 VAC. This includes drives for both LV and HV systems. The PowerFlex 753 and 7555 models come in voltage ratings between 200 VAC and 690 VAC. However, models like the PowerFlex 755TS is limited to 400-480 VAC.
• Power Ratings: For varying power requirements, the PowerFlex 7 series drives have power ratings ranging from 0.37 kW (or 0.5 Hp) to 24 MW (or 34,000 Hp). The PowerFlex 700S, for example, can provide as little as 0.37 kW for small machinery, while the PowerFlex 7000 series handles large-scale applications up to 24 MW.
• Frequency Tolerance: The drives have a frequency tolerance range of 47 Hz to 63 Hz. This extends operational flexibility in environments with fluctuating frequencies and enhances stability in cases of variable electrical frequencies.
• Input Phases: Many models in the series, like the PowerFlex 70 and PowerFlex 755, can operate with both single-phase and three-phase inputs. However, single-phase input reduces the output, typically around 50% of the drive’s three-phase capacity.
• Efficiency: The PowerFlex 7 series drives have achieved an efficiency of 97.5% of the rated amps.
• Power Factor Displacement: These drives offer a power factor displacement of 0.98. This leads to only minimal energy losses, hence increasing the system’s efficiency.

Control Features: Precision and Flexibility

The PowerFlex Series 7 includes drives with a diverse range of control methods for different applications.

• Frequency Control: Different drives in this series are equipped with different methods of frequency control and, hence, different ranges. For example, the PowerFlex 700H drives can have a speed regulation of 0.5% across a 40:1 speed range.
• Speed Control: For vector control, there are options available for both, with feedback and without feedback. The PowerFlex 700H and 750 series drives deliver speed regulation of 0.1% over a 120:1 range, while feedback-based vector control improves accuracy to 0.001% over a 100:1 range.
• Torque Regulation: Without feedback, the PowerFlex 700H achieves ±5% torque regulation. When feedback is introduced, this improves to ±2%. This increased accuracy is ideal for applications such as lifting.

Advanced Control Methods

The PowerFlex 7 series drives cater to different control requirements with different methods:

• Flux Vector Control with Encoder: This option incorporates an encoder that provides precise control of speed and torque in dynamic load conditions.
• Sensorless Vector Control: This approach is affordable as it does not require more sensors. For situations where affordability and ease of use are crucial, this approach is perfect.
• Volts per hertz Control: The V/Hz establishes proportionality between frequency and frequency and is suited for applications with widely variable speeds.
• Permanent Magnet Motor Control: These drives can also control the Permanent Magnet Synchronous Motors (also called PMSMs).

Safety Features

Safety is paramount in any industry’s automation, and PowerFlex 7 drives offer both hardwired and integrated safety options.

• Safe Torque Off (STO): PowerFlex 7 drives come with STO as a standard safety feature, which cuts the motors’ power when there is an emergency or during maintenance. Both hardwired and networked STO options are available, with networked STO providing the added benefit of centralized control.
• Safe Speed Monitor (SSM): The SSM feature ensures that the motor does not cross the acceptable limit. This feature can be important for high-speed applications.
• Networked Integrated Safety: This feature is available in high-end models like the PowerFlex 755. This feature integrates various safety functions, like safe brake control and safe direction, within a networked system.

Diagnostic and predictive maintenance capabilities

The PowerFlex 7 series’ capacity for predictive and diagnostic maintenance is one of its best qualities. The drive’s performance is regularly examined by sophisticated monitoring algorithms for pre-fault detection. This increases equipment life and helps avoid unscheduled downtimes.

For instance, the TotalFORCE technology, for motor control and real-time feedback, is incorporated into the PowerFlex 755 and 755T drives. All these can increase the life of equipment and help avoid unscheduled downtimes.

Customization and Scalability

The PowerFlex 7 series drives have a modular design. This feature is important to mention as it allows the system to be expandable and adaptable to changing applications. Models like the PowerFlex 753 and 755 have numerous option slots, which allow users to add I/O modules, safety features, or communication interfaces. This makes these drives future-proof for expansions.

Additional Features

• TorqProve Technology: TorqProve monitors real-time torque levels to handle loads accurately. This feature is designed for lifting applications such as cranes and hoists.
• Regenerative Capability: The regenerative feature of PowerFlex 7 drives helps with regulating energy consumption by feeding back energy from the motor to the supply. This curbs the need for additional energy-dissipating equipment.
• Roll-In/Out Design: PowerFlex 755 drives feature a roll-in/out design that eases servicing activities like installation and maintenance.

Communication Options

Another benefit of the PowerFlex 7 series is that it can be seamlessly integrated into industrial automation systems. With built-in EtherNet/IP, models like the PowerFlex 755 offer real-time data interchange and Ethernet network control features. The additional communication options like ControlNet, DeviceNet, PROFIBUS DP, and Modbus/TCP allow the drives to interact with a variety of control systems.

Conclusion

The wide variety of control methods, safety features, and diagnostic capabilities of the PowerFlex 7 series drives make them a complete solution for a number of applications. These drives represent state-of-the-art VFD technology. By understanding the specific needs of their operation, industrial professionals can unlock the full potential of PowerFlex 7 drives, optimizing performance, improving efficiency, and ensuring safety.

Don’t let inefficiency or outdated equipment hold you back. Upgrade to PowerFlex 7 today and experience the future of motor control. Call or email us now to find the perfect drive for your operation, all backed by our two-year Do Supply warranty. If you would like to read more, we have a guide on integrating, installing, and maintaining your new PowerFlex 753 Drive here.