Electrical engineers and designers face a set of variables that often have a significant impact on a finished copper component. The following information illustrates this design process by listing the importance of key specifications related to producing efficient copper bus and electrical ground bars.
In many cases, the options described may be limited in application because of copper alloy or other metal considerations, manufacturing capabilities, or simply the high cost of copper in today’s market.
Copper Bus Bar Efficiency: Make no mistake, size really matters
Bus bar systems for industrial and commercial facilities are often designed to save costs, with the bus bars sized to the minimum safety requirements permitted by local electrical codes. Often the future operating costs are ignored during the design stage, which can result in large amounts of wasted electrical energy due to the inefficient bus-bar conductivity or heating.
While opting for larger cross-sections of bus bar can result in more efficient power distribution grounding systems – with less heating and lower operating costs – the optimum system is one that properly balances initial costs with operating costs in order to minimize total life-cycle cost.
Energy is most often wasted in power or grounding systems because a portion of the electricity flowing through the conductor (bus or ground bar) is converted to heat rather than being delivered as usable electrical energy. The factors that determine the rate at which heat is generated by a bus bar system include:
• The amperage of the system with several factors that determine the resistance.
• The design of bus bar, the cross-section dimensions and the system layout.
• The conductivity of the bus bar metal, e.g. Copper vs. Aluminum.
While inefficient electrical conductivity leads to heat loss, there is a proportionally inverse relationship between the two that can be solved by increasing the bus bar dimensions. Yet the effects of the amperage and the bus bar dimensions are harder to discern.
Once the bus bar dimensions are set and a system is laid out, any increase in amperage down the line will increase the heat loss. Designing a larger cross-section of bus bar will naturally decrease electrical resistance and heat loss. But when is enough, enough?
Interestingly, the effects of amperage vs. dimensions are nonlinear. Thinner, wider bus bar systems actually have better heat-dissipation characteristics and run cooler than heavier bus bars that have less surface area. Since electrical resistance rises with temperature, the thinner, wider configurations are better conductors. Go figure.
| Here’s an illustration:
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Click here to view a set of key ampacity tables.
For customers who lack an engineering degree or Einstein’s brain, please be aware that in addition to this design guide, Storm Copper Quality Team members are on hand to review your specification and provide assistance in discerning ways to reduce cost and lead times.
You can reach them by calling Storm’s OEM Hotline: 1-800-394-4804
| Here’s what Storm’s co-owner, Dan Kitts, writes about copper bus bar fabrication…
Whenever Storm’s process engineers look at a bus bar print, there are a handful of key design elements they are immediately drawn to. These design elements largely dictate how an OEM’s bus bars will be manufactured. And it also determines the price we must charge to the customer. When considering the design of a bus bar, several critical points can favorably impact the cost of fabrication. Each falls within a quality process that Storm calls “Value Engineering…” Read the rest of Dan’s Value Engineering Blog … |
Copper Bus Bar Fabrication and Plating – Important Considerations
Storm manufacturers copper bus and electrical ground bars and kits for installations including perimeter grounding, telecommunications centers, towers and antennas. In each of these installations, one of the key factors in producing a cost effective busbar begins with layout of the required holes. From a fabrication standpoint, on copper busbar less than .500” thick, punching holes is much more cost effective than milling holes. The holes in a busbar are always punched in while the stock is flat, and then any required bends are made. When holes are specified too close to a bend, the holes can become distorted slightly. Even a slight distortion can prevent the installation of other components when tolerances are tight, so the only solution is milling holes that are designed too close to a bend. Milling is a slow and expensive process that is easily avoidable by allowing a distance of 1.00” or more from a hole location to a bend in the part.
Another reason that drives up costs, through required milling is tolerance. When hole placement tolerance is less than +/- .005” it is impossible to hold these dimensions on our punch presses. Also, the tolerance of the hole diameter is a concern. When specifications call for +/- .001, we must use a mill to drill the hole. To avoid incurring the additional costs of milling, keep your tolerances to +/- .020”.
It is important to note that punching copper busbar does slightly deform the surface of the part. Occasionally this indenting or rounding of the surface of the busbar can result in a loss of contact area. This minor deformation of the hole is rarely a problem, but worth noting.
Storm’s prototyping capability can also put samples of bus bar connectors in your hands for evaluation in a matter of days. And because Storm offers in-house bus bar electroplating of tin, lead, tin/lead alloys and silver, lead times critical OEM delivery requirements are reduced. Plus internal plating is more cost effective than outsourcing.
Un-plated vs. Tin-plated?
Pure Copper Grounding Bars are the industry standard because of the excellent conductivity of copper. But Storm also offers in-house electroplating of fabricated bus bar. This allows quick response to critical OEM delivery requirements. Moreover, internal plating is more cost effective than outsourcing.
Tin-Plated Grounding Bars can be a better choice for outdoor or other harsh environments, as tin electro-plating reduces the chance of corrosion interfering with the ground connection. Tin plating also disguises the copper color, serving as a secondary theft deterrent, while making the copper unusable for illegal recycling.
Security Ground Bar Kits are also available to prevent theft of copper by replacing the standard hex bolt configuration with Truss Spanner Security Bolts.
For more information on protecting against copper theft, check out our Copper Crime Center
Storm also offers custom stamping for theft prevention. Allow us to stamp your company name, logo, phone number, or a Do Not Recycle message into each ground bar. For more information, link to our live chat center or call toll free: 1-888-334-2177. |
Ground Bar Kits were developed by Storm to save time and money, and include the following components:
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| One .25″ thick grounding bar of solid copper (110 Electrolytic Tough-Pitch). Standoff Insulators: A Mounting Brackets: B Stainless Hex Bolts: C Stainless Spring-Lock Washers: D |
| Storm also offers Clear Polycarbonate Ground Bar Cover Kits to protect workers and equipment from accidental contact with live voltage. |
