Safety Standards

Enhance safety with the right medium-voltage drive

Drives with industrial safety features can help reduce safety-related risks, costs, and downtime in electrical equipment.
By Pat Lemmon May 2, 2019
Courtesy: Intermountain Electronics

Safety standards for electrical equipment continue to evolve — and many companies struggle to keep up with them.

Stringent standards are needed to protect workers. According to the Fire Protection Research Foundation, the manufacturing industry accounted for 15% of non-fatal electrical injuries from 2003 through 2010. The most common injury events associated with electrical hazards are electric shock, arc flash and arc blast, according to “Occupational Injuries from Electrical Shock and Arc Flash Events,” a study from the Fire Protection Research Foundation.

Many companies struggle to stay current with fast-changing safety standards. Sometimes they can’t find the time or funds to perform tasks required by the latest standards. Other times, they don’t have the right skills in-house to remain compliant.

Medium-voltage drives with safety features are helping companies overcome these challenges and can help support compliance with electrical safety standards. They can even change how workers do their jobs and reduce their exposure to risks as well as reduce downtime resulting from safety procedures. As an added benefit, by reducing safety risks, the drives can help companies reduce their insurance costs.

When evaluating drives with safety features, consider three primary goals:

1. Achieve compliance with arc-resistant drives

Arc-flash events can be unexpected, with the ability to strike workers who are doing nothing more than standing near electrical equipment. With the potential to exceed 35,000 °F, they can be highly dangerous to both people and equipment.

When working within an electrical hazard zone, consider specifying medium-voltage drives that offer arc-flash protection. In addition, look into the different levels of protection based on factors like accessibility level and current rating.

For example, some drives offer arc-flash protection only when all equipment doors are closed. Most often, workers are in front of equipment when they need to open the low-voltage panel doors to troubleshoot or service components—protection is even more important.

A drive with type 2B protection helps protect personnel in the event of an arcing fault whether they are in front, at the side, or in the rear of the enclosure. It also will maintain type 2B protection when the low-voltage door is opened for maintenance and repairs.

2. Reduce downtime with functional safety

Safely maintaining a motor and the equipment connected to it in heavy industrial operations can be a time-consuming task. Workers need to follow a formal and lengthy lockout/tagout (LOTO) procedure before they can perform tasks like replacing a coupling, cleaning a fan, or investigating a motor with a vibration.

This medium-voltage drive, the Allen-Bradley PowerFlex 7000 Drive System with ArcShield Technology from Rockwell Automation, also has regeneration capabilities. The arc-resistant system is certified to meet global arc-resistant standards. The system provides an arc fault rating up to 50 kA and meets Type 2B accessibility protection standards. Courtesy: Intermountain Electronics

This medium-voltage drive, the Allen-Bradley PowerFlex 7000 Drive System with ArcShield Technology from Rockwell Automation, also has regeneration capabilities. The arc-resistant system is certified to meet global arc-resistant standards. The system provides an arc fault rating up to 50 kA and meets Type 2B accessibility protection standards. Courtesy: Intermountain Electronics

It’s not only a maintenance issue. Many batch-production operations require that workers make mechanical adjustments between each batch. The adjustment itself may take 10 minutes, but the full shutdown time required can take one hour or longer.

Functional safety engineering practices significantly can reduce this downtime while still meeting strict safety standards. How? By integrating safety features into the drive’s design.

One such safety feature is safe torque off (STO), which removes rotational energy from a motor and anything connected to it. STO can reduce the downtime impact of maintenance and troubleshooting tasks, and can reduce the time required for the previously mentioned mechanical adjustments in batch operations from one hour to less than 15 minutes.

An STO safety feature also can help reduce wiring, hardware inventory and installation costs because it is designed into a medium-voltage drive’s control and, thus, doesn’t require additional electromechanical components.

3. Reduce risks, boost uptime with remote monitoring

The best way to enhance industrial safety is to reduce workers’ exposure to potential risks. One way is changing how workers interact with a drive.

Today, operators who need to monitor and control drives at the application are exposed to operating equipment and potential electrical hazards. By integrating the drive with the control system architecture, workers can monitor and control drives from a control room or using a remote human-machine interface (HMI). This can minimize the need for personnel to enter an e-house and interact with equipment.

Industrial operators also can benefit from remote monitoring in ways beyond safety. They also can use it to monitor critical applications with high downtime costs. The ability to track data such as alarms, status, uptime, warnings and faults can help workers respond to downtime issues—or prevent them from occurring in the first place. Likewise, the ability to track assets in remote locations, like mines or oilfields, can help operators dispatch technicians when, or perhaps even before, issues arise.

Traditionally, power-distribution equipment and motor-control equipment use different communication protocols. They’re connected to different networks, even though they are located next to each other in the same control room. This made creating a simple and integrated control system much more complicated than it needs to be. Today, there are simple and completely integrated solutions that allow the user to monitor and control all electrical equipment in the control room.

Organizations struggling to find or retain skilled professionals to monitor equipment can assign that responsibility elsewhere. Third-party remote monitoring services can monitor drives and other equipment continuously and notify on-site staff of any detected faults, warnings or abnormal performance variations.

Benefits beyond safety

Industrial safety may not be top-of-mind when specifying, buying or installing medium-voltage drives. However, organizations that leverage drives with safety features can help protect workers and also reduce downtime, better monitor drive diagnostics and mitigate skills-shortage challenges. 

Pat Lemmon is director of technical support, Intermountain Electronics. Edited by Chris Vavra, production editor, Control Engineering, CFE Media, cvavra@cfemedia.com.

MORE INSIGHTS

Keywords: medium-voltage drives, machine safety

Medium-voltage drives that are arc-resistant and can reduce downtime should be major considerations.

Changing how workers interact with a medium-voltage drive also can improve safety.

Choosing industrial drives with safety features can improve worker safety and reduce downtime and other potential challenges.

Consider this

What other safety features should be considered when choosing a medium-voltage drive?

Learn more from the New Products for Engineers database.

See an Intermountain Electronics article from April linked below.

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Pat Lemmon
Author Bio: Pat Lemmon, director of technical support, Intermountain Electronics.