Control Panel Design: Tips and Tricks

Enclosure ratings, filters, input and output, networking, and safety are among enclosure design considerations.

04/24/2012


All control panel design activity must start with an awareness of the enclosures working environment. Follow the NEMA environmental rating for the area for all components in the panel. For example, in many food plants all external surfaces are coated daily with sanitizing foam producing airborne corrosives, and then rinsed with 80 lb force of hose-directed water. This requires NEMA 4x rated equipment for this area. Using a NEMA 12 enclosure, which provides some protection against water ingress from dripping or light splashing, would not meet the requirements of this area. Don’t mix and match components within an enclosure, in particular for externally mounted devices on the panel.

Where risk of arc flash exists, panels should be externally stickered, alerting workers of such risk. Requirements for working in such panels should include wearing appropriate personal protection equipment for the panel.

When dealing with pneumatic equipment in the panel, always exhaust the air outside the panel. A recommended practice is to put the pneumatic penetrations low in the panel. Moisture in pneumatic air is a common problem, so placing the entry low will insure there are no drips on electronic equipment, should moisture ever become a problem. It is also a good idea to use a low micron prefilter for biologics and some water, coupled with a coalescing filter, to remove the majority of water in the air.

From an equipment protection standpoint, wiring conduit penetrations should never be at the top of the panel. Moisture and water in conduit lines are not that uncommon. Penetrations near the bottom are the safest from an equipment protection standpoint but will be harder to work with for the electricians. Mid-level side-mount penetrations are a common compromise.

While not necessary, systems will be easier to maintain over time with true earth grounds versus floating grounds. This can help mitigate panel equipment damage in the event of inadvertent cross-connects between two different potential levels.

Input/out racks

A good practice is to segregate signal types. TriCore engineers group discrete I/O and analog I/O by voltage type. Always run analog signals in shielded cable. It is a good practice to minimize interference as combining different voltage types in internal panel wiring ducts. (Conflicting voltages should cross at right angles to minimize interference.)

Motor control panels

Motor starters and drives often have networked cable. Generally this should be isolated from high-voltage cable, unless using a high-voltage-rated Ethernet cable. It is a best practice to have a physical barrier within an enclosure for high- and low-voltage sections, although size and cost considerations often come into play. Touch-safe terminals should be used, with cover plates used for high-voltage power distribution.

- David McCarthy is president and chief executive officer, TriCore Inc. Edited by Mark T. Hoske, content manager, CFE Media, Control Engineering.

www.tricore.com

www.nema.org

http://controleng.com/integration



No comments
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.
2017 Lubrication Guide; Software tools; Microgrids and energy strategies; Use robots effectively
Prescriptive maintenance; Hannover Messe 2017 recap; Reduce welding errors
Safety standards and electrical test instruments; Product of the Year winners; Easy and safe electrical design
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
Future of oil and gas projects; Reservoir models; The importance of SCADA to oil and gas
Diagnostic functions for system safety; Specifying industrial enclosures; Effective decision support for a crisis
Transformers; Electrical system design; Selecting and sizing transformers; Grounded and ungrounded system design, Paralleling generator systems
Natural gas for tomorrow's fleets; Colleges and universities moving to CHP; Power and steam and frozen foods

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