Managing your power: How to get started
So you want to begin a power management program. The goal is reduced energy expenditures. First of all, it's critical to recognize that the cost of using electrical energy has three main components.
So you want to begin a power management program. The goal is reduced energy expenditures. First of all, it's critical to recognize that the cost of using electrical energy has three main components. The most noticeable component, the electric utility bill, is like the proverbial tip of the iceberg.
A second cost component arises from power distribution and application within the plant. This cost represents a huge investment in capital equipment, depreciation, and maintenance. Additional infrastructure costs frequently arise because plant electrical systems and equipment can be affected by poor power quality.
The third component is total downtime costs. Equipment failures and unexpected shutdowns are just part of the problem. The real, total cost of downtime can include items such as overtime, scrap/rework, restart time, and lost sales.
Budget constraints are a common obstacle to getting started in power management. Although expenditures to lower the "traditional" cost of power (the utility bill) are fairly easy to justify, management may be reluctant to commit additional capital unless an attractive return on investment can be projected. Identifying the hidden costs of power, such as equipment problems and downtime, is more difficult than metering quantity, yet it can result in dramatic savings.
The key to success is to devise a power management process that helps identify these costs and make corrections. Finances might dictate a modest start, but once you've established some results and proved the benefit of the system through real savings, expanding the program can be justified. An effective power monitoring system can pay for itself in surprisingly little time.
Details can vary from one plant to another, but these four steps are the common sense backbone of a sound strategy to get power management started.
1. Take inventory. To improve any system, it's necessary to determine where you are and where you want to go. The first step in determining where you are is to inventory the plant electrical system, if that hasn't already been done. This work can be divided into three tasks. The first is to catalog electrical equipment in terms of age and condition. Keep the records simple and focus on identifying weaknesses. The second task is to catalog, update, and organize electrical drawings. Finally, update equipment labels.
2. Establish a baseline. Use portable power monitoring instruments to check quantity and quality of power on each plant circuit for at least a month. Quantity : Verify charges on your utility bill. Quality: Even circuits that seemingly have no problems may reveal some surprises. If the needed expertise is not available inhouse, the cost to hire a qualified engineering firm to complete this phase of the program is money well spent.
3. Install the right tools. A key aspect of power system improvement is to record the electrical phenomena that can cause disruptions in the facility. Inventory and baseline measurements should provide a pretty good idea of the "trouble spots" and other areas where permanent monitoring may be useful. There is virtually no limit to the number of measurement points, other than your ability to digest all the information. (See "The right tools" for important features of a permanent power monitoring system.)
4. Analyze the information and make informed decisions. With the power monitoring system in place you are ready to create power system improvements. The focus should be in three main areas -- energy savings, productivity improvements, and system reliability.
Energy savings normally focus on demand control. The monitoring system can attack energy costs from a whole new approach. For example:
- Allocate energy costs to departments
- Identify and control your peak demand charges
- Check utility billing charges
- Negotiate power rates with your utility.
Productivity improvements focus on efficiency (both equipment and maintenance) and improving power quality. Using information from the baseline study and the power monitoring and control system you can:
- Improve equipment efficiency
- Improve maintenance efficiency
- Improve power quality.
Reliability improvements , like every part of the power management process, are ongoing. Ways to improve system reliability include:
- Reviewing events for repetition
- Evaluating equipment reliability
- Evaluating system reliability improvements
- Extending equipment life.
Growing the system
With the power monitoring system in place and producing power cost savings, you now are in an excellent position to grow the system and take the power management process to the next level.
You started simple, with circuit monitors and software that enabled you to gather data and analyze it with a PC to make power system improvements. You had the foresight to install the right tools. You specified a flexible system with communications and networking capability.
Now you can grow the power monitoring system to interface higher level networks and multiple users. You can share the information with various departments within the company over the existing plant communications network or over a Windows NT platform. You can even create a system to analyze power in multiple facilities across the country, managing and sharing the data over the internet.
With the system, you can use historical data to estimate new facility loads. You can use load profiles to help plan system expansions. Current load profiles may even help delay expansions and defer equipment purchases.
With a comprehensive power management system, the possibilities for savings are enormous.
The electric bill represents only one of the costs of using electricity.
Tasks required to implement a power management program can be divided into four steps.
Choose a power monitoring vendor whose hardware, software, and services can meet needs for growth.
The author is willing to answer questions concerning this article. Mr. Eggink is available at 615-287-3500. The company web site is at www.squared.com.
A related article is "A 10-step program for improved power quality" (PE, April 1999, p 84, File 0501).
See the "Electrical power distribution and application" channel on www. plantengineering.com for more articles related to this topic.
The right tools
A permanent power monitoring system should include these features.
Metering accuracy. Look for true RMS operation and better than 0.25% accuracy on energy readings. Remember that a 2% error is $2000 for a $100,000 power bill. Also make sure power factor doesn't affect accuracy, and look for a meter that doesn't require recalibration.
Power quality information. The system should have waveform display capability. Ask if voltage and current waveforms are taken simultaneously so that meaningful comparisons and harmonic analysis can be done.
Communications. Make sure that the network for connecting meters to workstations is robust and capable of withstanding the worst environmental conditions. Make sure that speed and number of connected devices and users are not limitations.
Software. The software package should be user friendly and easy to reconfigure. It should support the most popular operating systems.
Datalogging. Logging is one of the major reasons for a power monitoring system, so look carefully at how it's done. There should be a combination of both nonvolatile memory logging at the monitoring devices and logging within the software for automated reports and trending. The ability to log waveforms and other event data is important.
Trending. Displaying plots and data over time is extremely useful in troubleshooting or planning upgrades. Be able to plot trends over any time window specified, and look for the ability to overlay trends from different monitoring devices on the same plot.
Flexibility. The monitoring system will need to grow and change with the electrical system. Look for ease of setup and configuration. Watch out for programs that require special programming.
Alarms and passwords. There are many options here, but as a minimum specify multiple password protection for a network environment, automatic alarm notification with a separate alarm log for quick reference, and the ability to customize alarm notification to fax, e-mail, or pager.
When you need help
When adopting a power management process, you will be expanding your knowledge of the power system and power quality solutions. But the learning curve can be steep. Even the best need to call for professional help once in a while. For one thing, the power management process dramatically multiplies the amount of information available. Figuring out what to do with the information can be daunting.
For this reason, you want to purchase a power monitoring system from experts that provide plenty of support options, such as those listed below.
Onsite commissioning and training. Learning how to use the new power monitoring system during installation is not a good idea. Setting up system files and alarm thresholds at the outset is best done by experts who can walk you through standard configurations. Customization can be done later.
Technical support line. Is phone support a free service during the warranty period? If not look at support options available to you. Phone support is essential during the first 6-12 mo of operation to get through difficulties and to help when you begin customizing the system.
Project engineering support. Every system has some degree of software, hardware, or communication integration. Give yourself a break and go with a vendor that has complete integration capabilities, like preconfigured workstations, custom software integration, and turnkey systems. Even if you don't need them now, it is nice to know the expertise is available should you need it later.
Training. Look for a complete training program that takes into account beginners and experts. A good program should not only offer software training, but power quality training as well.
Remote monitoring. A service to remotely monitor the power monitoring and control system could be invaluable to plant engineers with limited time and human resources. Any remote monitoring service should provide history file logs, onboard data logs, and power quality disturbance waveform readings uploaded within 24-hr after they occur. You may want to include immediate notification by digital pager or voice messaging when an event or alarm occurs.
Consulting services. Some power quality problems seem to defy logic. It helps to have a consultant available that is familiar with your monitoring system and can access information readily from it. Often the answers to the problem may be available deep within the data stored in your logs or from seldom used metered values. These experts can find it for you, saving time and expenses in "reinventing the wheel."
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