Faster tripping: Speed lowers energy, boosts arc-flash safety at Shell refinery

Vaasa, Finland -- Shell Canada is realizing improved operator safety at its Sarnia-based petrochemical refinery with an electrical arc protection system. The Vamp Ltd. system uses light and current sensing and protects the continuous-processing plant against costly nuisance trips.


Vaasa, Finland -- Shell Canada is realizing improved operator safety at its Sarnia-based petrochemical refinery with an electrical arc protection system. The

Vamp Ltd.

system uses light and current sensing and protects the continuous-processing plant against costly nuisance trips.

The upgrade, prompted by recent refurbishments, involved the increase in capacity of overhead electricity lines that feed the refinery, potentially taking the incident energy level at the air-insulated switchgear substation to more than 100 calories per square centimeter. Such a level would demand use of cumbersome personal protective equipment (PPE) and is above levels prescribed by Shell’s electrical safety policies in the area.

Shell Canada follows the NFPA 70E standard and, wherever possible, avoids live work on equipment with incident energy levels above 40 calories; live work is prohibited on equipment with energy levels beyond 100 calories. If levels are between 40 and 100 calories, then equipment should be scheduled for service during plant shutdowns. If not, live work can only be sanctioned following detailed hazard analysis that account for equipment age, maintenance history, access, and ability to perform required tasks wearing 100 calorie PPE.

The company sought a solution to optimize operator safety and minimize nuisance trips because the plant operates continuously, protected by a fail-safe, emergency shutdown system. Nuisance trips can result in financial loss, as they can initiate a sequence of controlled shutdowns that halt production, necessitating time-consuming controlled start-up.

Use of specialized arc light sensing technology meant that the system would trip within 7 milliseconds, providing faster, more efficient protection than stand-alone over-current relays or busbar differential devices, and reducing incident energy levels. Current sensing capability enabled safeguarding against nuisance trips that any single-sensing system might experience.

The system can be programmed to sense electric arc conditions using simultaneous light and current data, or light sensor information only, and operates less than a quarter of the time of traditional alternative technologies.

"The Vamp system has given us a simple add-on for the switchgear at this plant that minimizes risk in the event of an arc flash, while also positively contributing to plant reliability", said Phil Lasek, electrical reliability specialist at Shell Canada. "The system's modularity also gives me welcome flexibility for future expansion and improvements."

Lasek verified the system before installation with the aid of a high-voltage engineering consultant. The engineers could not verify the tripping speed to the finest accuracy, as they had no practical way of generating a true arc flash and fault simultaneously. But they devised a triggered flash bulb system and simulated fault current arrangement that could measure the response speed with a resolution that proved incident energy will not exceed 35 calories/cm2. Lasek believes that actual incident energy level would be considerably less, but to ensure operator safety he nevertheless protects the staff for the 35 level — using the next grade higher PPE equipment, rated to 42 calories. The

multi-zone capability of Vamp 221

minimizes ongoing costs, and Lasek recently extended the system to protect a secondary busbar in facility substations.

For related reading, see:

Arc Flash Evolution

Control Engineering News Desk
Register here and scroll down to select your choice of eNewsletters free .

No comments
The Top Plant program honors outstanding manufacturing facilities in North America. View the 2013 Top Plant.
The Product of the Year program recognizes products newly released in the manufacturing industries.
The Engineering Leaders Under 40 program identifies and gives recognition to young engineers who...
A cool solution: Collaboration, chemistry leads to foundry coat product development; See the 2015 Product of the Year Finalists
Raising the standard: What's new with NFPA 70E; A global view of manufacturing; Maintenance data; Fit bearings properly
Sister act: Building on their father's legacy, a new generation moves Bales Metal Surface Solutions forward; Meet the 2015 Engineering Leaders Under 40
Cyber security cost-efficient for industrial control systems; Extracting full value from operational data; Managing cyber security risks
Drilling for Big Data: Managing the flow of information; Big data drilldown series: Challenge and opportunity; OT to IT: Creating a circle of improvement; Industry loses best workers, again
Pipeline vulnerabilities? Securing hydrocarbon transit; Predictive analytics hit the mainstream; Dirty pipelines decrease flow, production—pig your line; Ensuring pipeline physical and cyber security
Upgrading secondary control systems; Keeping enclosures conditioned; Diagnostics increase equipment uptime; Mechatronics simplifies machine design
Designing positive-energy buildings; Ensuring power quality; Complying with NFPA 110; Minimizing arc flash hazards
Building high availability into industrial computers; Of key metrics and myth busting; The truth about five common VFD myths

Annual Salary Survey

After almost a decade of uncertainty, the confidence of plant floor managers is soaring. Even with a number of challenges and while implementing new technologies, there is a renewed sense of optimism among plant managers about their business and their future.

The respondents to the 2014 Plant Engineering Salary Survey come from throughout the U.S. and serve a variety of industries, but they are uniform in their optimism about manufacturing. This year’s survey found 79% consider manufacturing a secure career. That’s up from 75% in 2013 and significantly higher than the 63% figure when Plant Engineering first started asking that question a decade ago.

Read more: 2014 Salary Survey: Confidence rises amid the challenges

Maintenance and reliability tips and best practices from the maintenance and reliability coaches at Allied Reliability Group.
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 Society for Maintenance and Reliability Professionals an organization devoted...
Join this ongoing discussion of machine guarding topics, including solutions assessments, regulatory compliance, gap analysis...
IMS Research, recently acquired by IHS Inc., is a leading independent supplier of market research and consultancy to the global electronics industry.
Maintenance is not optional in manufacturing. It’s a profit center, driving productivity and uptime while reducing overall repair costs.
The Lachance on CMMS blog is about current maintenance topics. Blogger Paul Lachance is president and chief technology officer for Smartware Group.