How To Specify An Arc Flash Relay
Consulting-Specifying Engineer magazine has an article about arc flash relays. The article notes:
"One way to defend against arc flash is to retrofit electrical cabinets with arc flash relays, which reduce arc duration by sending a trip signal to the upstream device faster than conventional over-current relays, thus limiting the incident energy and protecting workers from hazards. In many cases, the protection provided by an arc flash relay can reduce the level of PPE required for compliance with NFPA 70E safety standards and OSHA workplace safety requirements."
Topics covered in the article include:
- How an arc flash relay works
- Where to install arc flash relays
- Arc flash relays and power analysis software
- Arc flash relays and zone identification
- How long of a delay?
- What to look for in an arc flash relay
Read the article in
Consulting-Specifying Engineer
Using Fiber Optics In Arc Flash Detection Applications
An article in Electronic Design magazine discusses arc flash detection methods and the use of fiber optics to increase the speed of arc flash detection. The article states:
"The primary components of an arc flash detection system (light and current detector) are the arc monitor unit, control unit, optical detector, current detector and current transformer. The control unit receives signals from both a high-sensitivity light detector and the upstream current transformer, enabling it to determine whether to trigger the circuit breaker. Clearly, this signaling process must be both fast and reliable to minimize danger and damage. Fiber optics, with its inherent speed and EMI immunity, make it a perfect medium for an arc flash detection system."
Read the article in
Electronic Design magazine.
See A Video Demonstration of Arc Flash Detection Using Fiber Optics
Engineers must consider arc flash prevention in the electrical systems. How important is timing?
A post on the Consulting-Specifying Engineer magazine's we site raises the question of timing. The post is called "Timing Is Everything." The opening paragraph poses the question:
"Because an arc flash relay depends on an existing circuit breaker to interrupt the current, does it make a difference in overall reaction time? And if the relay must wait until an arc forms, will the relay take longer to trip than the circuit breaker would trip on its own? Finally, how does the reaction time of an arc flash relay compare to an overcurrent protection relay?"
The question is, do arc flash relay actually work? What do you think?
Read the
Consulting-Specifying Engineer post here.
Man Burned In Electrical Explosion at CSU Channel Islands
The Ventura County (Calif) Star reports that:
"Two male subcontractors were preparing for maintenance work on a substation behind Ironwood Hall when an electrical explosion occurred, burning one of them.The other man pulled him off the equipment, and two campus police officers got him out of the substation."
Read the article here.
Arc Flash Incident Offers Learning Moment
Last week, Mark Reichanadter, Chief Operating Officer at SLAC National Accelerator Laboratory, wrote about a recent arc flash incident they had. He said:
"Last week, while performing regularly scheduled maintenance on SLAC’s linear accelerator, there was a mechanical equipment failure of a 12 kilovolt power supply which resulted in an “arc flash” explosion. I am very thankful to say that no one was hurt during this serious event."
"Those relatively new to SLAC may not know we had an arc flash in 2004, which resulted in serious burns to a worker and a major investigation by the Department of Energy (DOE). These events brought about major changes to how the laboratory performed work."
"In last week’s incident, we avoided injury because we followed our work planning and control process: define the work scope, identify and analyze hazards, develop and implement hazard controls, and perform work within controls."
Read More
First reconfigurable DC solution to reliably detect electrical arc faults
Introduced as the industry’s first fully-programmable DC arc-detect reference solution, the RD-195 has been unveiled by Texas Instruments (TI). The device makes it faster and easier for designers to address a growing need to safeguard high-power DC systems, such as automobile and aircraft battery management systems, industrial factory equipment, and photovoltaic units, against the catastrophic damage that can result from arc faults.
Designers can program the RD-195 to optimize the balance between arc-detection accuracy and false detection prevention to meet their system needs. The RD-195 is accompanied by a software application tool that enables alteration of threshold detection parameters.
More information.
Integrating maintenance requirements into the design of an electrical system is an important first step to provide workplace safety.
"Safety-related maintenance requirements for electrical equipment are outlined in Chapter two of NFPA 70E: Standard for Electrical Safety in the Workplace, but they are often overlooked to the detriment of both worker safety and a company's reputation. Using the concepts and strategies in Chapter two can enhance the company’s worker safety, productivity, and positive image."
An in-depth article in Consulting-Specifying Engineer magazine looks at ways that electrical equipment design can improve workplace safety.
Read the article here.
The article concludes by stating: "Engineers can design the hazard out of work tasks by specifying electrical products that have enhanced safety features, by specifying products that address both design requirements and operation of the facility, and by incorporating improved installation techniques is a strategy that will not only increase worker safety, but also increase productivity and profits."
Arc Flash Boundaries
Ensure Electrical Safety by Following New Arc Flash Guidelines
An article by Jack Rubinger provides introductory information on NFPA 70E b2012 and discusses the eight arc flash boundary zones. The article quotes Gary P. Larkins of APS/PowerSafetyPRO as stating:
"Effective electrical safety programs begin with achievable goals. Many organizations pursue safety training, arc flash hazard analysis, PPE selection, labeling and electrical safety program development as independent projects, when for an effective safety program, they are really interdependent. Strategic planning can reduce program investment, implementation time and provide enhanced worker safety,"
The same page also has links to a free guide to arc flash labeling.
Read more at:
Arc Flash Boundaries
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| Photo by J.M. Garg |
A Flock Of Birds Causes Arc Blast And Fire
The accumulated weight of more and more pigeons landing on an electrical wire caused the wire to sag until it came into contact with another wire. The result was an electrical explosion and hundreds of fried pigeons. The article in the Hunts Post reports that:
"This extraordinary event in Benwick Road, Ramsey Forty Foot (United Kingdom), on February 22, was witnessed by Ron Laverick who says it was reminiscent of Alfred Hitchcock’s film The Birds."
"Mr Laverick, of Benwick Road, Ramsey Forty Foot, said:'Sparks went everywhere, some pigeons were incinerated, others dropped into the ditch and the fire raged.'"
Read the story and see a photo (click here) of the burned area in the Hunts Post.
Two Workers Injured By Arc Flash At Space Launch Facility
KPPC radio reports that "Two workers for a company that launches spacecraft for the U.S. government were seriously injured in an electrical explosion at Vandenberg Air Force Base on the California coast."
The two employees were transported to a Los Angeles hospital. There is no information available about what caused the arc flash.
Read the story here.
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