Manage power, shield processes, save money

March 1, 2004
Automated power-management technologies are crucial in preserving continuous, critical production.

Suppose your company is at the top of its form. Your manufacturing facility has the latest production technology for continuous processing. The plant uses state-of-the-art programmable logic controllers as well as industrial and personal computers and systems and technologies. Your operators and managers are superior. The factory produces a highly competitive, sought-after product. Your marketing team is top-notch.

But, for an instant, the workspace lights and computer screens flicker. The disturbance could be caused by a voltage sag or dip—or an increase, called a swell—caused by the out-of-specification power supplied by the local utility, or even an in-plant system. Also responsible could be transients, which are shorter than sags or swells, and other power-related causes.

That disruption also just briefly dimmed your company’s advantages. Downtime and materials loss will cost you money. There may be damaged equipment, including variable-speed drives and electronics. Such problems also weaken your competitiveness in the supply chains to which your company is connected, because on-time or ahead-of-time deliveries are critical in today’s markets.

A protective remedy is power management. It encompasses handling both power quality and reliability of supplied energy. Different approaches exist for automating power management to protect your facility. One type of common system is the uninterruptible power supply or UPS system. This power-conditioning technology focuses on “both quality and reliability, but it’s really there for reliability. It’s there to provide power to vital plant systems, including safety-shutdown systems, production equipment and automation equipment,” says Harry Forbes, a senior analyst at ARC Advisory Group, Dedham, Mass.

Another solution is the use of voltage regulators to handle the milliseconds-long sags or dips in power. These regulators can be either process-specific or plant-wide. In the former, stand-alone units are located proximate to the process. In the latter, units are typically located outside the plant, where the utility’s power supply enters.

Yet another answer could be to retrofit devices to give operators more access to them. This is an approach that Schneider Electric has chosen, says Forbes. “Schneider’s whole strategy is to use Web technologies to give visibility into their technology. What’s important is that they can retrofit these capabilities onto a wide range of products.”

An even more all-inclusive solution is energy management. Power is momentary, while energy is the integration of power over time. Energy management should encompass activities such as power-profiling and automation of equipment, as well as installation of monitoring and/or protective equipment, including meters and voltage regulators, respectively. Comprehensive energy management requires a company to first quantify its energy consumption, via profiling. Then strategies must be devised to optimize that usage information. Finally, the manufacturer must install whatever systems or equipment are needed to realize those cost savings.

Using those technologies “could include manual intervention or complete automation. We use hardware and software to quantify energy consumption. We use power monitors, digital meters that are networked,” says Al Hamdan, senior engineer with Rockwell Automation’s Power and Energy Management Solutions group, in Milwaukee. “Typically that could include ControlNet, Ethernet or whatever network the customer has. Once we do that, we collect energy information.”

Two types of software are used to gather those data, he says. One is load-profiling, cost-allocation software; the other is energy-management software. These “(visually) chart consumption and demand for electrical energy. We could also import data for water, gas and steam—from any energy meter in the plant.” The manufacturer can then enter the utility tariff (price being paid for the power) into the software and create “shadow bills.” These are checks of the bills generated by the utility that can be matched against those shadow utility bills. With this view of usage, “the customer can see where he is using electricity. Now he can look at various processes, see where they can be altered and run (them) in a different demand period to try to reduce consumption,” Hamdan says.

After the consumption pattern is found, problem recognition occurs. The manufacturer can “identify the power-quality problems—for example, harmonics, voltage sags or swells, transients or voltage imbalances,” Hamdan explains. That will help the company reduce power interruptions. A real-world example of energy/power-management, he says, involves a North American food-processing company. One reason it is interested in reducing power budgets is that the corporation established an annual energy budget, which it then exceeded by approximately $30 million to $50 million. “The company’s goal is to reduce total energy consumption by 5 percent to 10 percent,” he says.

What is occurring now at the facility is load profiling and cost allocation. That is because the company “wants to know for each product how much energy costs. We’ve identified the processes they want to quantify—mixing, slicing, packaging, palletizing, for example—in hot dog and cheese manufacturing. The plan encompasses meters that are spread strategically throughout each plant,” says Hamdan. Those meters link to load-profiling software, he says. “It is Web-enabled and uses Microsoft’s .Net. That allows the software to send data to the server, which means that you can access the information from anywhere in the world.” The data can also be used to identify power-quality anomalies, he adds.

For this food manufacturer, for which the energy-management project began in the past six-to-12 months, he says, “we’ve got a plan for multiple U.S. facilities. The specs are written already. More than 50 meters have been purchased for a couple of plants. That covers about eight critical processes in each facility.” Plans call for getting the data onto the Web and then training other plants’ operators on what to do to reduce power costs, he says.

The company still must confront sags, though. At one facility, the company “had an average of 12 outages (sags) per year. Each one of those cost approximately $15,000 per minute. Typically, the outages are short interruptions, often less than a minute. But even that can cause havoc. The client would clean out mixers or dump the entire batch because of standards requirements.”

Those interruptions decrease production efficiency, which Hamdan says, “the client correlates with dollars. Today, production efficiency was 85 percent to 90 percent. They’d prefer 85, at least, but 90 would be better. They’ve noticed with power sags that the production efficiency was 83 percent to 84 percent. When you quantify difference in dollars for all 12 sags, it’s approximately $80,000 to $90,000 per year.” He adds that the company will try to leverage the new power monitors, which are being installed for load profiling and cost allocation, “to capture these power-quality events and then try to correct for them.”

See sidebar to this article: Regulated Voltage finds us everywhere

See sidebar to this article: What is a power sag or drip?