Selecting the right industrial automation equipment, such as motors, drives, and communication modules, involves paying close attention to a lot of details. For example, there are notable differences between the North American National Electrical Manufacturers Association (NEMA) standards and those of the International Electrotechnical Commission (IEC) in Europe, especially when it comes to motor and drive ratings.

When picking motors, drives, and controllers, some key factors to think about include input and output voltages (and their tolerances), speed range and regulation, torque needs, acceleration, braking duty cycles, and any special requirements, like quick torque or speed response. Environmental factors, including how to manage heat, are also important.

Communication requirements can vary depending on where the equipment sits in the overall industrial control system. For instance, at the factory floor level, protocols like IO-Link work well for smart sensors and actuators, while EtherCAT, PROFINET, Modbus, and others handle communication for motion control, safety systems, I/O, and vision

At the highest level of factory automation, Ethernet/IP is commonly used to connect automation controllers, programming interfaces, and even the cloud. HMIs often connect through protocols like DisplayPort. Between the factory floor and the top levels, a mix of Ethernet/IP, EtherCAT, and similar protocols are used to link field-level equipment with operations and control.

There’s a lot more detail than we can cover in just one discussion, but this article highlights some important factors to keep in mind when specifying motors, drives, and communication modules. You’ll also find examples of equipment and protocols from manufacturers like Siemens, Phoenix Contact, Omron Automation, Panasonic Industrial, and Schneider Electric.

Shifting Focus

Motors and drives are a common element in many industrial automation systems. To start, it's useful to see how motor efficiency plays into the broader performance of these systems and how the focus is changing.

Using higher-efficiency motors can save up to 6% in energy, which is great. But when you add a high-efficiency drive along with supporting components, you can boost that energy savings to as much as 30%.

The real game-changer happens when the focus shifts to overall system optimization. By considering all the mechanical components and integrating communication systems that tie into the Industrial Internet of Things (IIoT)—from operational and plant levels to the enterprise level and the cloud—you can achieve up to 60% energy savings and increase productivity as well (Figure 1).

Figure 1: Increasing levels of integration and communication result in more energy savings and higher productivity. (Image source: Siemens)

Ecodesign for Motor Systems

Part 2 of IEC 61800-9, titled “Ecodesign for motor systems - Energy efficiency determination and classification,” can be a valuable resource. Rather than focusing solely on motor efficiency, it outlines a set of higher-level performance factors for "electric motor-driven systems." Variable frequency drives (VFDs) are viewed as part of a complete drive module (CDM), which includes the AC input or "feeding section," a "basic drive module" (BDM) like a VFD, and "auxiliaries" such as input and output filters, line chokes, and other support components.

The standard also defines a power drive system (PDS) as the CDM combined with the motor. Moving up the hierarchy, the motor system is described as the PDS plus motor control devices like contactors.

At the top level, you have the extended product, or the overall system (as shown in Figure 1), which includes mechanical drive equipment like a transmission and the load machine. For a more detailed look into the IEC 61800-9-2 PDS efficiency standards

The motor is the starting point for specifying “electric motor-driven systems.”

Motor Matters

Electric motors can be highly efficient if they’re properly specified and used. This makes choosing the right motor an important job for machine designers.

The IEC measures motor power in kilowatts (kW), while NEMA uses horsepower (hp), which are easily convertible. However, IEC and NEMA use different methods for calculating efficiency, so an IEC nameplate efficiency might be a bit higher than the NEMA rating for the same motor design.

The actual efficiency of a motor is closely linked to its specific application. Therefore, motor efficiency standards are often discussed in terms of energy loss reductions rather than just absolute efficiency.

IEC 60034-30-1 defines five motor efficiency classes, from IE1 to IE5, with energy losses decreasing by 20% between each class. For instance, an IE5 “Ultra Premium” motor has 20% lower losses compared to an IE4 “Super Premium” motor. It’s important to note that in some cases, a higher efficiency motor might have a lower power factor (PF).

In North America, NEMA has fewer energy efficiency classes, but they’re still significant. NEMA also includes motor service factors (SF) not covered by IEC standards. For example, a NEMA motor with an SF of 1.15 can run continuously at 115% of its rated capacity, though it may run hotter, potentially shortening bearing and insulation life.

Instead of SF, IEC uses ten duty types or service factors (S1 to S10) based on factors like continuous versus intermittent operation, speed variations, and braking.

While operating voltage and frequency ranges differ between NEMA and IEC, both use “per unit” (p.u.) quantities to express these ranges. In the p.u. system, values are fractions of a base value. NEMA uses one range for motor voltages and frequencies, while IEC uses two “Zones” (see Figure 2).

Figure 2: Comparison of NEMA and IEC industrial AC voltage and frequency ranges. (Image source: NEMA)

Driving for PDS Efficiency

Motor drives are crucial for achieving PDS efficiency as outlined in IEC 61800-9-2. They can be categorized in various ways, such as motor voltage, power level, motion types, and supported applications. Motion types can be classified as continuous or discontinuous and further categorized by performance levels: low, medium, and high based on the maximum power output needed.

Different drives cater to various system requirements. Servo drives and motors are ideal for applications like robotics that require fast acceleration, deceleration, and precise positioning. Soft starters work well for continuous operations such as conveyors that need smooth startup and deceleration. Variable frequency drives (VFDs) are versatile and used in many industrial machines.

Some VFD product lines are tailored for specific functions like pumping, ventilating, compressing, moving, or processing. For instance, Siemens’ SINAMICS G120 series offers universal drives with power ratings from 0.55 to 250 kW (0.75 to 400 hp), suitable for general industrial applications in sectors such as automotive, textile, and packaging.

The Model 6SL32203YE340UF0 operates on 3-phase power with a voltage range of 380 to 480 Vac ±10% / -20%. It is specified for 400 V operation with motors rated from 22 to 30 kW in Europe and 480 V in North America for motors rated from 30 to 40 hp (see Figure 3).

Figure 3: This VFD can be used with motors rated from 22 to 30 kW, depending on the operating voltage. (Image source: DigiKey)

VFDs are not the only key to efficient PDS design. For a deeper dive into the necessary support components, check out the article “What support products does it take to maximize the impact of using VFDs and VSDs? - Part 1.”

Communication and System Optimization

While motors and drives operate at Level 1 on the factory floor, or the field level, they aren't at the lowest tier of the Industry 4.0 communication hierarchy. That spot is occupied by functions like sensors and actuators at Level 0. Moreover, there are several levels above the field level. To achieve the highest efficiency, productivity, and sustainability in Industry 4.0 factories, timely and efficient communication up and down the hierarchy, all the way to the cloud, is crucial. Cloud connectivity is supported by protocols such as (see Figure 4):

• uOPC PubSub Bridge: This consolidates multiple operational technology (OT) data streams.
• MOTT Broker: This receives messages and forwards them to users based on the message subject.

Figure 4: All levels of the Industry 4.0 communications hierarchy can connect directly to the Cloud. (Image source: OPC Foundation)

• There’s more to Level 1 than just drives and motors. Field bus master units (FMUs) can play a crucial role in facilitating communication and simplifying the integration of drives and other devices. FMUs come in various protocols, such as PROFINET, PROFIBUS, DeviceNet, CANopen, and more. Using FMUs can allow for manufacturer-independent connectivity.
  
• For example, the Panasonic Model AFP7NPFNM is a PROFINET FMU. It includes integrated function libraries for programming software, which can significantly cut down the time needed to develop application-specific solutions.

• Level 0: Sensors, Actuators, and Safety

• To maximize the energy savings from VFDs, it's important to enhance connectivity down to Level 0. Integrating sensors, actuators, and safety devices like light curtains at Level 0 can significantly boost efficiency improvements and push energy savings beyond 30%.
  
• Common protocols for connecting Level 0 functions include DeviceNet, HART, Modbus, and IO-Link. IO-Link is a point-to-point protocol that links sensors and actuators to higher-level controls. It can be used as either a wired or wireless standard and is becoming more popular in Industry 4.0 due to its cost-effectiveness.
  
• Omron’s NX-ILM400 IO-Link master units allow for mixing standard I/O with high-speed synchronous I/O. The standard digital I/Os offer 16 connections per unit with options such as (see Figure 5):
• Four 3-wire sensor connections with power supply
• Eight 2-wire contact inputs or actuator outputs
• Sixteen 1-wire connections for sensors and actuators connected to a common power supply

Figure 5: This IO-Link master unit supports both standard and high-speed synchronous I/O. (Image source: Omron Automation)

Level 2 for PDS and Beyond

Higher-level communications can enhance field-level operations, but they're crucial for maximizing organizational efficiency and productivity. Connecting from Level 2 to Levels 3, 4, and the cloud requires protocols like Ethernet/IP, EtherCAT, and Modbus TCP/IP.

To make these connections, you can use equipment such as programmable logic controllers (PLCs) or industrial personal computers (IPCs). PLCs are designed specifically for industrial automation and control. In a typical setup, a PLC monitors machine inputs and related sensors, makes decisions based on its programming, and sends out control commands.

IPCs, on the other hand, can perform similar functions but are more general-purpose. They run operating systems like Linux or Windows, offering access to a broad range of software tools, and are often connected to human-machine interfaces (HMIs). While PLCs are more machine-focused, IPCs provide a wider range of operational functions.

The line between PLCs and IPCs is becoming increasingly blurred. For instance, the Phoenix Contact 1069208 PLC runs the Linux operating system. It can be programmed using symbolic flowchart (SFC), ladder diagram (LD), function block diagram (FBD), and structured text (ST). It features three independent Ethernet interfaces and can connect to the PROFICLOUD.

For applications that benefit from IPCs, Schneider Electric offers the HMIBMIEA5DD1E01 IIoT Edge Box. This fan-less design features an Intel Atom Apollo Lake E3930 dual-core processor running at 1.8 GHz, a mini PCIe expansion slot, and nine communication ports (see Figure 6).

Figure 6: Fanless IPC with a mini PCIe expansion slot and multiple communication options. (Image source: Schneider Electric)

Conclusion

This article has offered a quick overview of key considerations for designers when specifying motors, drives, and communication modules for Industry 4.0 setups. While it’s not exhaustive, it aims to provide some helpful insights and resources for further exploration.