Improper relay logic threatens your electrical assets and investments


While event recorders are powerful tools, their output is only as good as their input. Integration engineers need to identify all elements that should be recorded in the event of a fault. However, it’s important to remember that event recorders have limited data capacity and will begin dropping old data from the file once that capacity is reached. Therefore, some elements should be left out of the event recorder depending upon how often they toggle. Best practices call for the engineer to structure the high-speed data capture for trips, abnormal voltage, or currents to aid in event analysis during future trip investigations.

3. Arc flash mitigation capabilities

Many microprocessor-based relays include an optional protection feature for arc flash detection. This feature can immediately respond to arc flash incidents by detecting a combination of excess light and current. The feature can help workers avoid devastating injury and prevent costly equipment damage.

To determine if this relay feature is needed in a specific environment, protection engineers can complete an arc flash hazard analysis to identify the potential for and location of possible arc flash hazards. Such an analysis may include recommendations to utilize microprocessor-based relays for additional arc flash protection. In these instances, the arc flash mitigation capabilities should be programmed into the protective relay, using logic to instruct the relay to immediately interrupt the circuit if developing arc flash conditions are detected.

4. Motor/generator protection features

Most industrial facilities, wastewater treatment plants, manufacturing facilities, and refineries operate a large number of motors, some of which cost tens of thousands of dollars. Large motors are expensive to repair or replace and lead times are long. Each motor can be effectively protected by one microprocessor-based relay. However, the features within the relay must be programmed correctly, per the motor manufacturer’s specifications and mechanical load, taking into consideration dynamic response of the facility’s power system.

Some motor protection relays allow for limiting the maximum starting time or maximum starts/hour to allow for adequate cooling of the motor during high-current, low-speed operations. Often, this function is underutilized or misunderstood and is either disabled or set to a value that does not adequately protect the motor. To take advantage of this function, protection engineers perform motor starting and load flow studies to determine the maximum motor starting times that can be expected under the most restrictive conditions. Relays are then programmed to prevent damage but still allow for adequate start times without nuisance tripping.

The installation of microprocessor-based relays isn’t “plug and play.” Relying on default logic can provide a false sense of security that may not be revealed until after severe equipment damage or unplanned outages have occurred.

Utilities and industrial facilities frequently make a critical mistake when upgrading to microprocessor-based relays by failing to customize the relays’ built-in programmable logic, thus forfeiting the relays’ ability to properly protect the electrical system. With the help of an experienced protection and/or integration engineer, utilities and facility owners can identify the features and capabilities within each relay that should be leveraged. By investing in proper relay logic customization and programming, facilities ensure optimum protection for their electrical systems and simultaneously realize the full value of their upgrade investment.

Steve Nollette is a supervising engineer for Emerson Network Power’s Electrical Reliability Services.

Key Points:

  • Changes in equipment and in electrical systems require expert installation of protective relays systems, but this often does not take place.
  • Simplifying the control system control system is a benefit, but can only be realized if custom logic has been programmed and tested.
  • An arc flash hazard analysis can identify the potential for and location of possible arc flash hazards. If found, that also can be programmed into the relay.
  • The installation of microprocessor-based relays isn’t “plug and play.” Relying on default logic can provide a false sense of security that may not be revealed until after severe equipment damage or unplanned outages have occurred. 

<< First < Previous Page 1 Page 2 Page 3 Next > Last >>

The Top Plant program honors outstanding manufacturing facilities in North America. View the 2015 Top Plant.
The Product of the Year program recognizes products newly released in the manufacturing industries.
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.
Doubling down on digital manufacturing; Data driving predictive maintenance; Electric motors and generators; Rewarding operational improvement
2017 Lubrication Guide; Software tools; Microgrids and energy strategies; Use robots effectively
Prescriptive maintenance; Hannover Messe 2017 recap; Reduce welding errors
The cloud, mobility, and remote operations; SCADA and contextual mobility; Custom UPS empowering a secure pipeline
Infrastructure for natural gas expansion; Artificial lift methods; Disruptive technology and fugitive gas emissions
Mobility as the means to offshore innovation; Preventing another Deepwater Horizon; ROVs as subsea robots; SCADA and the radio spectrum
Research team developing Tesla coil designs; Implementing wireless process sensing
Commissioning electrical systems; Designing emergency and standby generator systems; Paralleling switchgear generator systems
Natural gas engines; New applications for fuel cells; Large engines become more efficient; Extending boiler life

Annual Salary Survey

Before the calendar turned, 2016 already had the makings of a pivotal year for manufacturing, and for the world.

There were the big events for the year, including the United States as Partner Country at Hannover Messe in April and the 2016 International Manufacturing Technology Show in Chicago in September. There's also the matter of the U.S. presidential elections in November, which promise to shape policy in manufacturing for years to come.

But the year started with global economic turmoil, as a slowdown in Chinese manufacturing triggered a worldwide stock hiccup that sent values plummeting. The continued plunge in world oil prices has resulted in a slowdown in exploration and, by extension, the manufacture of exploration equipment.

Read more: 2015 Salary Survey

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.
The maintenance journey has been a long, slow trek for most manufacturers and has gone from preventive maintenance to predictive maintenance.
Featured articles highlight technologies that enable the Industrial Internet of Things, IIoT-related products and strategies to get data more easily to the user.
This digital report will explore several aspects of how IIoT will transform manufacturing in the coming years.
Maintenance Manager; California Oils Corp.
Associate, Electrical Engineering; Wood Harbinger
Control Systems Engineer; Robert Bosch Corp.
This course focuses on climate analysis, appropriateness of cooling system selection, and combining cooling systems.
This course will help identify and reveal electrical hazards and identify the solutions to implementing and maintaining a safe work environment.
This course explains how maintaining power and communication systems through emergency power-generation systems is critical.
click me