FROM BRAINS TO BRAWN CONTROL PANEL & ENCLOSURE BEST PRACTICES
REXELUSA.COM Page 2 From Brains to Brawn Best Practices for Control Panels & Enclosures In industries like manufacturing, control panels are the brains of the operation. They’re what make all the heavy-duty machinery (the brawn of your operation) run. And just like our brains, they need protection—that’s where enclosures come in. This guide provides you with best practices that will keep your automated processes running smoothly. This best practice guide is designed to help you better build control panels and select the right enclosures. These tips will save you both time and frustration. If you are new to panel building and unfamiliar with some of the associated terminology, we’ve created a glossary in section three of this book.
CONTROL PANEL & ENCLOSURE BEST PRACTICES Page 3 Part I – Control Panels: The Brains of Your Operation Page 04 Options for Building Your Control Panel Page 04 Layout & Design Considerations Page 06 Layout Checklist Page 09 Part II – Enclosures: Protecting Control Panels Page 10 Keeping Control Panels Safe Page 10 Enclosure Sizing Page 11 Part III – Glossary: Components & Terms Page 14 Basic Components Page 14 Control Panel Terminology Page 16 Control Panel & Enclosure Guide
REXELUSA.COM Page 4 Part 1 – Control Panels: The Brains of Your Operation When you are installing a new control panel, there is a lot to consider. First, your manufacturing and engineering teams must make decisions about the overall panel function. Control panels are designed to do two things: ⏹ Provide and control the flow of electrical power to equipment, typically electric motors ⏹ Control how your equipment operates within the framework of your distributed control system (DCS). To break it down further, that means making sure: ⏹ Any safety devices you have on your plant floor properly talk to your control panel, which in turn will talk to a motor to shut it down as required. ⏹ Your control panel can talk to your enterprise and production systems to communicate what is happening at the machine and equipment level. Production personnel can gather data to monitor and improve manufacturing processes. Options for Building Your Control Panel How you handle your electrical control panels depends on several things, including time, experience, and cost considerations. Let’s look at the three basic options for building your control panel. #1. OUTSOURCE Partner with a third-party contactor Rexel. When you work with us, we can modify your enclosures and fabricate your panels to your specifications. ⏹ Enclosure Modifications – Custom holes, cutouts, knockouts, and other modifications ⏹ Panel Build – Component installation and wiring #2. DIY DIY means do it yourself, and that’s exactly what this option entails. You purchase an off-the-shelf, standardsized stock enclosure. You purchase all the different components: drives, a PLC, power supplies, fuses, DIN rail, panel duct, ethernet cable, glands, mounting plates, etc. Your team uses hand power tools to make cutouts, openings, and access points in the enclosure. Your team drills and taps holes and starts installing components. And then your team does the electrical wiring for both the control components and power.
CONTROL PANEL & ENCLOSURE BEST PRACTICES Page 5 #3. PLUG & PLAY This is an inbetweener. It is not as hands-off as an outsourced option, but some of the involved work from a DIY option is taken off your plate. You order a custom enclosure. You provide a rough idea of what components will be involved. You receive a partially finished panel, an enclosure with some amount of DIN rail, duct, pre-drilled and pre-tapped holes, and components pre-installed. Your team can then complete the field wiring. Many end-users in the world of automated manufacturing take advantage of the plug-and-play option. It allows them to take the pre-fab and pre-install work that isn’t in their wheelhouse off their plate. It keeps the critical work under their supervision and control. They are not entirely reliant on a third-party contractor, which helps them manage in-house maintenance and upgrades. If you’re interested in options two or three, but lack experience building and working with control panels, this guide packed with information and advice from our in-house experts will help.
REXELUSA.COM Page 6 Layout & Design Considerations SPACE Your control panel will contain any number of components based on your needs (drives, circuit breakers, ducts, PLCs, power supplies, wires, etc.). And they all need to go somewhere. When you start designing your panel, there are a number of things to consider. Dimensions Measure and do the math. Whether you’re pulling out a tape measure or a manual, you need to get the dimensions for each item to ensure proper fit and functionality. They are also an important aspect of selecting the right enclosure (more on that in the Enclosure section). Clearance Some components such as drives require minimum mounting clearance to ensure proper performance. Be sure to factor clearance requirements into your layouts. Temperature Heat dissipation is critical to the function of your control panel. Try to place heat-sensitive components such as drives lower in the panel to escape rising heat. And, when necessary for thermal management, consider adding heat sinks, fans, and air conditioners. Another way to help reduce heat-related issues is to use flange-mounted drives. These are designed to have the heat sink fins outside the enclosure, putting the major heat source away from your electronics. Future Additions: Do your future self a favor and consider what additions to your control panel may be needed down the line. Leaving adequate space can make future modifications easy (and keep costs down). Note: Triple check the physical fit of your componentry. Buying and modifying the wrong size enclosure is a costly mistake and best avoided. There are many types of 3D modeling software out there that you can use to help you perfect your panel design. A few we like are SOLIDWORKS and Inventor®. Using 3D modeling software can also bring together all the benefits of programs like ProposalWorks and files from enclosure manufacturers (like nVent HOFFMAN).
CONTROL PANEL & ENCLOSURE BEST PRACTICES Page 7 GROUNDING & BONDING In today’s industrial environment, proper grounding and bonding are essential. Modern manufacturing environments use computers, precision instrumentation, data collection, and internet connections—all of which require electricity. Grounding Grounding means connecting current-carrying elements to earth to protect the power system’s equipment and provide a return path to the power source. There are several ways to ground your system, but the best practice is delta/wye with grounded wye neutral. Doing this increases safety by providing a direct path for common mode current, and it controls common mode noise current. Bonding Bonding means connecting the conductive elements that don’t normally carry current to put them all at the same potential, creating a low impedance path back to the source. Bonding alone does not increase safety; the system still needs to be grounded. However, it does protect equipment by reducing current flow between pieces of equipment. A properly grounded and bonded system is safe and helps control common mode noise. ROUTING WIRES & WIREWAY Additional considerations for your control panel layout are wireway and voltage routing. Mixing together power, signal wire, unshielded cables can result in failures. Within your enclosure, try to keep the most space possible between your various cables and wires. Even something as simple as a shield between your wireways can help prevent issues.
REXELUSA.COM Page 8 TRICKS WITH TERMINAL BLOCKS Terminal blocks are common components of control panels. There are a variety of types and ways to use them in your panels to save you both time and space. Modular Design The modular aspect is interesting because it gives panel builders great flexibility for fit and arrays. For example, you could arrange a row of terminal blocks 20 long or design two banks of ten each. Your panel design should focus on the critical components first, meaning things that require cooling, or special connections/cabling, or priority placement in the mechanical layout. Once you’ve determined that, the modularity of terminal blocks makes your placement quite a bit easier. Saving Space with 2-Tier Terminal Blocks The modularity and configurability of terminal blocks are great when you are creating a brand-new control panel. But let’s say you are an electrical or controls engineer tasked with either retrofitting new control elements into an existing panel or making all your automation components fit into a specified standard-sized enclosure. Both can be challenging. One way to save space is to go double-decker, more commonly known as 2-tier, also known as multiple level feed-through and doublelevel. There are also 3-tier and 4-tier varieties. Multi-level terminal blocks provide a means of plugging-in discrete electronic components, circuit protection fuses, or circuit isolation disconnect plugs to help save valuable panel space. Essentially, banks of terminal blocks like this double the amount of available discrete wiring points without changing the actual physical footprint of square inches used in your back panel. They snap in and out easily to DIN rail mount systems. They’re modular and configurable. Saving Time with Push-In Terminal Blocks If you or your team spends hours every week putting wires into terminal blocks, you might consider that a task that you’d like done faster. Push-in devices give you and your team a quicker connection that requires no double checking. The push-in connections significantly exceed UL pull-out standards.
CONTROL PANEL & ENCLOSURE BEST PRACTICES Page 9 Layout Checklist We’ve designed the following checklist to save you time and frustration. It’s something to go through while you’re still in the planning phase to ensure you’ve considered all the constants and variables of a control panel build. Consider it a map of where components will go. Your goal should be to create a panel that delivers the power required to equipment, keeps your people/plant safe, and communicates correctly with your control systems. This checklist will help you do all of this. Double-check physical fit of overall panel footprint on the factory floor Double-check physical fit of componentry, actual sizes What material will your enclosure be? Three common options: — Painted carbon steel (mild steel) **Most common — Stainless steel (SS) — A non-metallic composite (e.g., polyester, fiberglass, or polycarbonate) Review other physical considerations — Heat dissipation (drives) — Mounting options – drilled & tapped holes — The weight of components and how they are mounted — Strain relief for the cord(s) Confirm field entry; i.e. where does the power come IN to the panel? Confirm knockouts and mounting options — Where is power going OUT? What is it going to? — What types of cables are going OUT? Do they need shielding? Investigate possible sources of electrical noise Consider power isolation — Review power and devices, i.e. low power / high power (also known as low voltage / LV and high voltage / HV) — Some devices can be located near to each other, some cannot — A general best practice is to put high-power devices by like devices — A general best practice is to put low-power devices by like devices (for example, 24V) — There is an emerging trend of using barrier panels (like this one from HOFFMAN)
REXELUSA.COM Page 10 Part II – Enclosures: Protecting Control Panels Protecting your equipment is important and challenging in a manufacturing environment. Automated equipment and machines are typically controlled with a combination of electrical and mechanical systems. These systems consist of motion (e.g., moving, turning, picking, and placing) and a host of other applications. The brains behind these systems are typically found in a nearby control panel housed in an enclosure. Keeping Control Panels Safe For a plant electrician or a factory maintenance person, the question is: How do I keep the brains in that control panel 100% safe? These control panels are typically found on a factory floor. There are an elevated number of mechanical hazards on a floor—everything from inattentive line workers to fork trucks and other materialhandling vehicles. Depending on your industry, the factory environment might be very hot and/or humid. If you are in a factory that manufactures food or beverages, you face additional challenges like washdown (also known as wash down or wash-down) procedures. ENVIRONMENT The environment can kill when it comes to control panels and their components. Where you place your enclosure matters. Best practice is to house your enclosures in a controlled environment, eliminating exposure to dust, water, heat, cold, and potentially corrosive and other harmful gasses. In reality, that’s not always possible. If your panels must reside on the plant floor, it’s critical that you are aware of the potential for exposures (e.g., grease, particles, gasses, chemicals, food, liquid, heat, cold, etc.) Then you select an enclosure that is properly rated for the environment, protecting both your panel and people working in the area. For heat and cold exposures, don’t forget to consider both seasons and time of day. When evaluating the environment, consider using a data logger to pick up on issues like afternoon sun exposure.
CONTROL PANEL & ENCLOSURE BEST PRACTICES Page 11 MATERIAL AND RATING Enclosures can be made of a variety of materials, including painted carbon steel, stainless steel 304 (also known as type 304), stainless steel 316 (or type 316), fiberglass reinforced polyester, and polycarbonate. They also have NEMA ratings and IP codes to specify the level of protection from the surrounding environment each enclosure provides. Stainless Steel Electrical Enclosures If your enclosure is a 304 or 316 stainless material, your in-house team might have a hard time doing these cutouts in a timely fashion—it takes a while to cut stainless steel. Or, if you make a cut wrong and have to scrap a piece, stainless steel enclosures can be a costly piece to waste. Sometimes, it just makes sense to have your enclosures hit your factory floor ready for wiring, with all the custom machining already done. The plug-and-play option is often easier for stainless steel enclosures. WASHDOWN Washdown is a high-pressure cleaning with water and/or chemicals designed to kill bacteria and other microorganisms. The enclosure of each control panel will have a NEMA rating. Even though there might be high-pressure water near to your control panel, there are ratings in place to help you use an enclosure appropriate for your environment. Stainless steel is typically the material of choice for washdown environments. Enclosure Sizing If you can’t fit all the components of your control panel into your enclosure, all you have is a very expensive cabinet—and another enclosure to buy. All the measurements you took when you designed your control panel should come in handy, but don’t forget depth. Whereas your design plans were flat, two-dimensional drawings, you need to account for all three dimensions when selecting an enclosure. Most enclosures are cube shaped, with three dimensions, namely: height (H, A), width (W, B), and depth (D, C). The A, B, C styled dimensional naming is common to HOFFMAN enclosures. ⏹ Small enclosures run from 8”, 10”, and 12” dimensions up to the 24-30” range. You can typically get them shipped by most major parcel carriers. ⏹ Medium enclosures are classified at 24-30” on one end up to 48” on the bigger end. They can typically ship via major parcel carriers when you order one or two, more than that may require a pallet. ⏹ Large enclosures cover anything 60” and up, with the 72” dimension being quite common in industrial control panels. These sizes will need their own dedicated skid or pallet.
REXELUSA.COM Page 12 LOGISTICS FOR LARGE ENCLOSURES When you need to ship a small enclosure via most postal carriers, it’s a relatively straightforward task. HOFFMAN enclosures come in a perfectly sized and matched package, along with appropriate cardboard spacers and corner edging for extra protection. Put a UPS label on it and done. Medium-sized enclosures can usually fit on a standard 48” x 40” wooden pallet. Large enclosures can weigh several hundred pounds. With one of this size and weight, you’ll want to think about a few extra steps: doors, heights, eye bolts, banding, and strapping. Dock Doors Make sure your shipping and/or receiving area has clearance to unload the enclosure. Here are some of the best guesses for clearance: take the dimensional height of the enclosure itself, add six vertical inches for the pallet, and add three vertical inches for the forklift. Those are bare minimums. A rule of thumb is that most of the height issues we see tend to happen between 86” and 102”. Accessories You should also meet with your engineering department to double-check if there are any accessories premounted or pre-installed to the top of the enclosure. This might include transformers, braking resistors, and/or stack lights. They will all add height to the overall piece. You really don’t want to shear any of these items off the top. Banding All medium and large enclosures must be banded to the skid. Banding is also known as strapping or steel strapping. It is typically a very thin metal product that goes around the enclosure. Be careful not to bend, ding, blemish, or mar your metal enclosure. Avoid applying too much pressure when you ratchet down. There are some very helpful published guidelines for how to move a banded enclosure/ skid, and when to remove banding. Eye Bolts Many HOFFMAN enclosures come standard with eye bolts installed, also known as lifting eyes. Typically, there are either two or four. This makes it easier for transportation, loading, and unloading. HOFFMAN recommends a (minimum) 3,000 lb.-rated chain or strap be used through the eye bolts. Keep your eye bolts in mind for the overall height, as well. They may add another three to four inches vertically. Most eye bolts are removable, so you can reduce height if facing a short clearance, but that does represent additional work.
CONTROL PANEL & ENCLOSURE BEST PRACTICES Page 13 Bolt Down This is another option for added security in shipping. Some enclosures may require bolting down to a custom pallet with added hardware. The hardware connects through predetermined pass-through points on either the back, bottom, or another point. This helps prevent damage to both the enclosure itself and to individuals tasked with moving it. A bolt down option is not standard but can often be added upon request. Custom Pallets and Crating This is another option for added shipping security. Essentially, a custom wooden framework is built and sized for your exact enclosure dimensions. If your job requires multiple enclosures ganged together, or perhaps a hybrid enclosure + wireway + mechanical system, then custom pallets and crating might be a fine idea. These methods are not standard and must be custom quoted. SAFETY FOR LARGE ENCLOSURES A large enclosure may need to be moved and processed, and that should only be done by a trained and qualified individual. Here is our quick list of the top ten safety tips: 1. There is a tip-over hazard. Always be aware that large enclosures can crush you, resulting in serious injury or death. 2. Stabilize the enclosure before removing strapping. 3. Before moving it, make sure that the route is clear of all obstructions. 4. The enclosures must be handled by a trained and authorized forklift operator only. This is required by OSHA Standard 1910.178 and ANSI Standard B56.1. 5. Know the safe lifting capabilities of the lifting equipment; be certain it can handle the weight and size. 6. Carefully position the enclosures on the forks, noting that they are top-heavy. 7. Keep the load against the carriage. Always tilt the load backward towards the fork’s mast. 8. Start and stop the forklift slowly and gradually; avoid jerking movements. 9. A person should assist the forklift operator at a safe distance (i.e., more than the height when guiding or directing movement of large, top-heavy enclosures). 10. Other workers should be away from the enclosure and at a distance that is more than the overall height. When we ship them, we like to include a very helpful eight-page document. It is titled, “Large Enclosure Safe Handling Requirements.”
REXELUSA.COM Page 14 Part III – Glossary: Components & Terms Basic Components The internal and external components for your control panel will depend on your applications. The numbers, sizes, and functionality of parts will vary widely between panels. This section provides basic descriptions for common components. This list is by no means exhaustive, but it will familiarize novices with terms they’ll encounter as they begin exploring control panels. INTERNAL Cable Glands – Glands are used to manage cable entry, meaning pass pre-terminated cables through an enclosure sidewall with no cutting or splicing. Cables may be of varying widths. You may need a water-tight seal. (Learn more about cable glands from icotek®.) Circuit Breakers – Automatic devices for stopping electrical current flow in a circuit as a safety measure. It generally has a disconnect on the outside of the enclosure. DIN Rail – Metal rail used widely for mounting industrial control equipment such as circuit breakers inside equipment racks. Typically made from steel, they are only for mechanical support. Drives – Industrial drives include variable frequency drives (VFD) to control AC motor speed and torque and servo drives to control, amplify, and transmit electronic current. Ethernet Cable – Networking hardware to connect equipment and allow communication (also known as patch cords). Fuses – There are a variety of fuse types from fast-acting to inductive loads to timing delays. Before making a selection, find the right fuse for your application. HMI – Human-machine interfaces (HMI) allow users to interact with a machine using physical input hardware (e.g., a keyboard) and output hardware (e.g., computer monitor). Mounting Plates – Plates used to mount equipment to the enclosure (also known as sub-panel or sub-plate). PLC – Programmable logic controllers (PLC) are industrial digital computers for controlling automated manufacturing processes.
CONTROL PANEL & ENCLOSURE BEST PRACTICES Page 15 Power Supplies – These are used to convert AC to DC voltage, converting electric current from a source to the required voltage, current, and frequency for the load. Signal Conditioners – Signal conditioners manipulate analog signals to meet the requirements for further processing. In industrial environments, they isolate, transmit, convert, split, and amplify to improve process reliability. Terminal Blocks – Insulated blocks that secure two or more wires together Transformers – Used to convert voltage and provide isolation. Wire Duct – Rigid trays used for routing and organizing cables and wires within an electrical enclosure. EXTERNAL Disconnect Handles or Switches – External means to safely disconnect power to the control panel inside the enclosure. Enclosures – Cabinets to hold the control panel and its components and protect them from the surrounding environment. Push Buttons – Buttons installed or connected to an enclosure to externally control operations.
REXELUSA.COM Page 16 Control Panel Terminology Now that you’re acquainted with the basic components of common control panels, it’s a good time to dig into lingo. Below we we’ll explain basic terms you may encounter as you design, layout, and build a panel. CIRCUIT PROTECTION The goal of circuit protection is to provide appropriate protection for downstream devices using fuses or circuit breakers. Keep in mind any overall SCCR (short circuit current rating) requirements for the entire system. SCCR does require calculations, which can sometimes be complex. CUTOUTS, KNOCKOUT, AND CUSTOM HOLES Enclosures need cutouts, knockouts, and custom holds to support a variety of functions, including wiring, push buttons, HMI, and handles and switches. These holes and cutouts need to be appropriately spaced to allow for proper control panel design and operation. You can create these on your own if you have the right tools, or you can outsource this work to save time and prevent costly errors. The HOFFMAN Certified Modification Center at Rexel makes precise, custom modifications every day.
CONTROL PANEL & ENCLOSURE BEST PRACTICES Page 17 ENCLOSURE TYPES NEMA Ratings NEMA (National Electrical Manufacturers Association) defines enclosure types based on various factors including environment, elements, hazards, degree of protection, potential exposures, and more. Each rating starts with protection against hazardous parts and then varies further based on additional environmental conditions. You can see a full listing of enclosure types and their definitions on the NEMA website. NEMA 1, NEMA 12, and NEMA 4X are frequently specified for electrical enclosure applications. NEMA type 4 and 3R are also common. IP Codes IP Codes (or Ingress Protection Code) are another type of enclosure rating. These codes classify and rate degrees of protection from intrusion, accidental contact, water, and dust. The first digit of the code refers to intrusion protection and the second digit is for moisture protection. HEAT DISSIPATION Drives create heat, and if your panel gets too hot, it can damage other components. Heat dissipation is key to ensuring your control panel is functional. Cooling You can use fans on the drives to move air to cool them down. You can also use heat sink devices. You can even use heat sink devices that mount externally on your panel. This keeps the heat out of your panel. Spacing Most drives will come with very specific published user guidelines about space (i.e., how much space to leave above or below or behind the drives to ensure they are properly ventilated which will help keep them properly cooled). It’s critical to know the minimum mounting clearances for each drive in your panel. Layout Heat rises. The temperature is higher at the top of a panel versus the bottom regardless of where you mount the heat-generating devices. Heat-sensitive components should be mounted as low as possible in your panel. PLCs and drives are heat sensitive.
REXELUSA.COM Page 18 MINIMUM MOUNTING CLEARANCES Referenced previously under Heat dissipation, following minimum mounting clearances is critical. Most commonly, you will mount drives upright on a flat, vertical, level surface. Prior to designing and laying out your control panel, be sure to verify the manufacturer’s clearance recommendations. POWER COMING INTO THE PANEL Identify what your incoming power requirements are and verify that all your back-panel components are rated for that power. If they are not, provide the appropriate measures (e.g., transformer or power supply) to convert the incoming power to the voltage needed. STAINLESS STEEL Stainless steel (also known as SS) enclosures are very common in wet environments: water, chemicals, machine fluids, cutting oils, etc. Stainless steel is designed to be resistant to corrosion, which makes it a natural choice to house a control panel in a plant that requires washdown. The same properties that make it resist corrosion also make it very tough to cut and machine properly. THERMAL MANAGEMENT There is only so much you can do to mitigate temperature with the heat dissipation methods mentioned above. Heat inside the enclosure can be impacted by other factors, including high ambient outdoor temperatures and manufacturing areas with hot materials. In these instances, air conditioning solutions can help. Heat isn’t the only factor in thermal management. There are also scenarios where you need to combat cold environments, like outdoor or refrigeration panels. In these instances, you’ll have to heat your panel. WASHDOWN Washdown refers to process of washing or cleaning surfaces for sanitation, appearance, and/or contaminant removal. Though pressure washing may be involved, washdown can simply involve rinsing. The process can use fresh water or the use of detergents and other chemicals.
CONTROL PANEL & ENCLOSURE BEST PRACTICES Page 19 From Top to Tail: Rexel Can Help We’re here to help. From panel design to custom enclosures to plug-and-play to full outsourcing—Rexel offers the products and services you need. Custom Control Panels We can save you time and money. Our custom control panel services provide built-to-order, performance-tested panels based on the needs of your applications, systems, and facility. Partner with us to take the guesswork out of your estimates and utilize a fixed-cost solution for your control panel fabrication challenges. For a complete overview of our custom control panel services see our Custom Control Panel Fabrication Services Overview Brochure. HOFFMAN Certified Modifaction Center Get custom enclosures on your schedule. We have the sizes and materials you’re looking for with the modifications you need. Our HOFFMAN Certified Modification Center will save you time and money with affordable, custom enclosures. IN-STOCK AND READY-TO-GO As an authorized HOFFMAN on Demand distributor, we have ready-to-ship stock based on local needs. This core set of products covers virtually every application, including: ⏹ Pushbutton, junction box, wall-mount, free-stand, floor-mount, and modular enclosures ⏹ HMI and industrial wireway ⏹ Thermal management solutions ⏹ Accessories FLAWLESSLY MODIFIED TO MEET YOUR REQUIREMENTS As your local HOFFMAN Certified Modification Center, we can make rapid holes and cutout modifications so you can also get faster access to pre-modified enclosures and back panels. You can rely on us to have the products you need available now. Whether you need an out-of-the-box enclosure or a custom modification, we can meet your needs. Contact us today: [email protected].
[email protected] Rexelusa.com ©2024 Rexel. All Rights Reserved. All supplier trademarks are the property of their respective owners. – 5/2/2024 Rexelusa.com