MCC innovations reducing the risk of arc flash incidents

With a pressure wave similar to a hand grenade and the potential to produce heat nearly four times the temperature of the sun, arc flash hazards pose serious danger. That’s why manufacturers across all sectors of industry are implementing techniques and practices designed to reduce these hazards and help protect workers.

03/01/2010


 

With a pressure wave similar to a hand grenade and the potential to produce heat nearly four times the temperature of the sun, arc flash hazards pose serious danger. That’s why manufacturers across all sectors of industry are implementing techniques and practices designed to reduce these hazards and help protect workers.

The causes of arc flash are usually accidental %%MDASSML%% for example, maybe a rodent or water accidentally enters electrical equipment or an employee accidentally forgets to tighten a connection. When this happens, an arc fault superheats the air around it, expands and creates a pressure wave within the electrical enclosure.

This arc plasma vaporizes everything it comes in contact with %%MDASSML%% copper, insulating materials, bolts and the steel enclosure %%MDASSML%% and can cause serious injury to workers. Injuries can include severe burns from the burning and vaporized materials, damaged hearing from the sound waves and impaired eyesight from the high-intensity flash.

Intensifying the focus

Historically, electric codes and safety standards did not directly address arc-flash hazards; they only addressed protection from fire, electrocution and shock hazard. But standards such as “NFPA 70E%%MDASSML%%Electrical Standard for Safety in the Workplace” are putting more focus on arc-flash risks and helping reduce the associated hazards in North America.

As codes and standards evolve, users are looking for leading-edge products capable of delivering higher levels of safety. Arc-resistant motor control centers and intelligent control systems are fulfilling that need in many applications. Such solutions offer improved safety features along with remote operation and monitoring capabilities.

Creating an effective design

An arc-resistant MCC is designed and built to provide a complete structural solution, with the ability to contain and redirect the arc energy away from personnel and capable of providing Type 2 accessibility. Type 2 accessibility, as defined within IEEE standard C37.20.7-2007, helps shield personnel on the front, rear and sides of an enclosure from the effects of an internal arcing fault. Core features should include:

  • Structural integrity through a solid, robust design

  • Two side sheets on every section

  • Well-isolated horizontal bus and vertical bus insulated in a nonconductive labyrinth support

  • Automatic vertical bus shutters

  • Unit isolation

  • Dedicated unit ground stab and vertical ground bus.

    • Rugged structural design and a well-supported, isolated and insulated bus system are critical for an MCC to withstand the effects of an arc-flash event. Two side sheets on every section and a robust bus support design contribute significantly to the ability of the equipment to contain and redirect the arc-flash energy.

      To help isolate and protect users from potentially hazardous voltages, the MCC should employ a solid grounding system, along with a well-isolated and insulated horizontal bus and vertical bus. For added safety, spaces which accommodate plug-in units should include automatic shutters that immediately isolate stab openings when units are removed.

      One of the newest features in MCC technology is the use of built-in networking and preconfigured software. By including a built-in industrial network, based on an open protocol like DeviceNet, along with MCC monitoring and configuration software, users can remotely monitor, configure and troubleshoot the MCC, minimizing the need for personnel to enter an arc-flash boundary zone.

      Clearing the confusion

      In considering an arc-resistant MCC, it’s important that users understand the performance criteria that must be met before the MCC can be classified as an arc-resistant design. “Arc-resistant,” as it applies to electrical equipment like low voltage MCCs, is a recognized industry term defined by IEEE C37.20.7-2007. The standard defines the test requirements that must be met and the expected performance equipment must deliver in the event of an arc flash.

      Some vendors may use terms like “arc flash-resistant” to describe their product with the implication that it offers substantiated arc-resistant capabilities. However, “arc flash-resistant” is not a standard industry term and has no relevant meaning behind it.

      Another area of confusion centers on the claim that keeping the doors of an MCC closed during insertion and removal of power stabs provides a lower risk, and therefore allows users to adhere to a reduced level of required PPE. The reality is no industry standard allows users to reduce the risk category of an MCC application just because the door is closed.

      Diligence pays off

      Ultimately, the best prevention against exposure to an arc flash is an in-house safety program that complies with the NFPA 70E standard. Beyond that, the most important advice is “shut it off.”

      Because of high-production volumes and the use of multiple and differing automation systems in a single plant, identifying and significantly reducing potential hazards can be a complex task. This means end users and employers must be diligent in their training practices and highly selective in their technology choices to increase workplace safety.

      The good news is advances in control technology make it easier with an expanded array of solutions designed to deliver improved safety, increased productivity and greater cost-savings.

      Employers must be diligent in their training practices and highly selective in their technology choices to increase workplace safety.

      Good maintenance practices can help lower maintenance costs by 60%.





Top Plant
The Top Plant program honors outstanding manufacturing facilities in North America.
Product of the Year
The Product of the Year program recognizes products newly released in the manufacturing industries.
System Integrator of the Year
Each year, a panel of Control Engineering and Plant Engineering editors and industry expert judges select the System Integrator of the Year Award winners in three categories.
June 2018
2018 Lubrication Guide, Motor and maintenance management, Control system migration
May 2018
Electrical standards, robots and Lean manufacturing, and how an aluminum packaging plant is helping community growth.
April 2018
2017 Product of the Year winners, retrofitting a press, IMTS and Hannover Messe preview, natural refrigerants, testing steam traps
June 2018
Machine learning, produced water benefits, programming cavity pumps
April 2018
ROVs, rigs, and the real time; wellsite valve manifolds; AI on a chip; analytics use for pipelines
February 2018
Focus on power systems, process safety, electrical and power systems, edge computing in the oil & gas industry
Spring 2018
Burners for heat-treating furnaces, CHP, dryers, gas humidification, and more
April 2018
Implementing a DCS, stepper motors, intelligent motion control, remote monitoring of irrigation systems
February 2018
Setting internal automation standards

Annual Salary Survey

After two years of economic concerns, manufacturing leaders once again have homed in on the single biggest issue facing their operations:

It's the workers—or more specifically, the lack of workers.

The 2017 Plant Engineering Salary Survey looks at not just what plant managers make, but what they think. As they look across their plants today, plant managers say they don’t have the operational depth to take on the new technologies and new challenges of global manufacturing.

Read more: 2017 Salary Survey

The Maintenance and Reliability Coach's blog
Maintenance and reliability tips and best practices from the maintenance and reliability coaches at Allied Reliability Group.
One Voice for Manufacturing
The One Voice for Manufacturing blog reports on federal public policy issues impacting the manufacturing sector. One Voice is a joint effort by the National Tooling and Machining...
The Maintenance and Reliability Professionals Blog
The Society for Maintenance and Reliability Professionals an organization devoted...
Machine Safety
Join this ongoing discussion of machine guarding topics, including solutions assessments, regulatory compliance, gap analysis...
Research Analyst Blog
IMS Research, recently acquired by IHS Inc., is a leading independent supplier of market research and consultancy to the global electronics industry.
Marshall on Maintenance
Maintenance is not optional in manufacturing. It’s a profit center, driving productivity and uptime while reducing overall repair costs.
Lachance on CMMS
The Lachance on CMMS blog is about current maintenance topics. Blogger Paul Lachance is president and chief technology officer for Smartware Group.
Electrical Safety Update
This digital report explains how plant engineers need to take greater care when it comes to electrical safety incidents on the plant floor.
Maintenance & Safety
The maintenance journey has been a long, slow trek for most manufacturers and has gone from preventive maintenance to predictive maintenance.
IIoT: Machines, Equipment, & Asset Management
Articles in this digital report highlight technologies that enable Industrial Internet of Things, IIoT-related products and strategies.
Randy Steele
Maintenance Manager; California Oils Corp.
Matthew J. Woo, PE, RCDD, LEED AP BD+C
Associate, Electrical Engineering; Wood Harbinger
Randy Oliver
Control Systems Engineer; Robert Bosch Corp.
Data Centers: Impacts of Climate and Cooling Technology
This course focuses on climate analysis, appropriateness of cooling system selection, and combining cooling systems.
Safety First: Arc Flash 101
This course will help identify and reveal electrical hazards and identify the solutions to implementing and maintaining a safe work environment.
Critical Power: Hospital Electrical Systems
This course explains how maintaining power and communication systems through emergency power-generation systems is critical.
click me