Grants Showcase
Powering up the Curriculum
Story by Jane Roberts
"There is a powerful agent, obedient, rapid, easy, which conforms to every use, and reigns supreme ... Everything is done by means of it. It lights, it warms, and it is the soul of . mechanical apparatus. This agent is electricity."
-Jules Verne, Twenty Thousand Leagues Under the Sea
Powerful, obedient, rapid-yes, but typically invisible. Other than the crashing sound of lightening striking or the flash of a bolt in the sky, can you describe what it looks like or say for sure if it has a sound?
Electricity is everywhere in our society, but how do you teach something so dangerously powerful yet seemingly illusive? Such questions about form and sound might sound elementary, but their implications are far reaching in the business world especially as the nature of how society uses electricity changes. Analyzing answers to these questions and exploring their implications is no small task. However, under the guidance of instructors Steve Senty, Marvin Gerth, Dave Plude, and Tim Simpson, students in the Construction Electrician Program at Anoka Technical College have been taking a real-world look at the function and form of electricity.
With the help of a Learning By Doing grant from the Minnesota State Colleges and Universities Center for Teaching and Learning, approximately 70 first-year students received a first-hand experience with power quality and dynamic waveform analysis in 2001. Using specialized test instruments and related peripherals that were purchased via the grant, students participated in a hands-on experience where they actually measured and evaluated power quality problems in electrical systems. To further enhance the learning experience, students ventured out into the community to perform these tests on the electrical services of local businesses. Focusing on real world situations, the students zeroed in on the two most prevalent problems facing electricians in the field today: power factor and harmonic distortion
Searching for the Perfect Wave
For most of the twentieth century, the predominant use of electricity for business and industry was to run electric motors, incandescent lights and resistive heating devices. Incandescent lighting and resistive heating applications don't really affect the electricity coming in from the utility company.
Electric motors, however, cause a phase shift between current and voltage. This phase shift is called Power Factor. When the waveforms are in synch, everything is perfect. But the further the current and voltage waveforms are out of synch, the worse the Power Factor is. Even though Power Factor has been on our electrical system since the turn of the nineteenth century, it did not become a significant problem that required remediation until later in the twentieth century.
Power Factor is a problem, because is causes unnecessary current on the distribution system and reduces the amount of useful power the system can carry. But how can you tell how much useful current your system is carrying? The only way Power Factor can be observed is to view the waveform relationship between current and voltage on a test instrument designed specially for these viewing purposes.
Another aspect of power quality is harmonic distortion. Harmonic currents are produced when companies use electricity to perform tasks in which the current flow is not directly proportional to the voltage. Harmonic currents do not cause a phase-shift like power factor; instead, they create distorted waveforms. But, like power factor, the only way harmonics can be observed is to view the current waveform on a test instrument with these specific capabilities.
Because harmonics are superimposed on the fundamental current waveform, the current waveform no longer follows a smooth sine wave. And most electrical equipment acts like a surfer looking for the perfect wave-- a smooth waveform. Unfortunately, all our modern equipment is having a negative effect on the quality of this perfect wave. A variety of devices, like our desktop computers and other microprocessor-based devices, create high levels of harmonic distortion.
In the past, this affected only a few industries, like steel mills and aluminum smelters that were powering huge furnaces. In the last 20 years though, there has been an explosion of microprocessor-based equipment, which use electricity that creates these disproportionate waves. And if you're reading this article online, you're creating those kind of waves right now. Of course computer systems aren't the only culprits. Other disproportionate wave producers include variable frequency drives, AC/DC converters, electronic ballasts, X-ray machines, MRI equipment and uninterruptible power supplies. Thus, what was once a problem for a very limited number of heavy industries is now a concern for some smaller business, too.
Because harmonics are relatively new to electrical systems, the problem of harmonics reaching levels severe enough to require remediation has actually only been around for the last ten to fifteen years, which means that about 80% of electricians in the field today do not know how to identify and analyze harmonic problems. Therefore, learning about them now in the field is "a huge opportunity," according to the instructors. Students will understand what harmonics are and how to detect them. Having this kind of experience and state of the art troubleshooting skills will be a significant asset for these students, their future employers and the clients they serve.
"Unfortunately," said one of the instructors, "most of the students have never been exposed to any other type of electrical work, and they think it is limited to wiring houses. And, they think they already know everything there is to know about electrical work, because they saw someone do it once. But the truth is, residential is not the only type of electrical work that's available. Opportunities also lie in commercial and industrial businesses. Students have no idea what positions they will hold in the electrical industry at this point in their lives. They think they know, but it is our responsibility to expose them to many different aspects of the industry. Getting them out of the classroom and into a real-world environment gives them a whole new perspective on what this kind of work is really about," they said
Seeing is Believing
Although power quality was already part of the curriculum, it was only the textbook theory. Even with an eloquent description, electricity can still be a tough concept to plug into. So the challenge became what to do to make these etheric concepts a little more concrete. They started in the classroom with traditional lectures about power quality, introducing the role of digital dynamic test equipment and the part that waveforms play in the analysis. Then, students read electrical trade journal articles to reinforce their understanding of the most common electrical power quality issues. They also worked in a lab, building test circuits and simulating different power quality conditions, and they made practice "field" tests of the college facility's electrical distribution system. Then, after studying the tools and techniques in the classroom, the class culminates in student's visiting local area businesses where they are able to take power quality readings on electrical services in operation.
"The problem with the classroom is that guys just become button-punching machines, working through written problems where all of the pertinent information is neatly listed in the problem . They've got a formula and they just plug numbers into equations without thinking about what they mean. But at a client site, not everything is in the nice neat order as it is in the classroom written problem. Real situations don't all line up for the calculator. When they get in the field, even though they've done the calculations in the book, they don't even know where to begin." At a site, they not only have to use their brains, but they have to reason. They have to gather the facts, analyze them, and determine the severity of the problem."
Behind the Scenes
When students arrived at the five different area businesses, including Home Furniture, Anoka Technical College, IMI Cornelius, APW Thermal Management, the Dolphin Car Wash and the residence of Helen Hemp, students would visually survey the types of electrical loads in the facility and, as a small group exercise, they would discuss the power quality problems associated with each of the loads. Connecting the test equipment to a laptop computer, students displayed and recorded the waveforms. Each student in the program visited and measured field readings on actual service equipment of 5 sites.
It took about six months to line up businesses that would allow students into their backrooms, because they were worried about liability issues if a student were hurt. The college was able to secure a letter from the State Attorney General stating that in the event of accident, they wouldn't be held liable. At first the instructors wanted to find businesses they could predict would have problems, but eventually they settled on any business that would let them in the door. The businesses that did open their doors to the classes were reported to be very understanding and tolerant of the inconvenience of having a class occupy their facilities for the entire day, with small groups of students going in and out that entire time. As a gesture of thanks, the students' readings, analysis information, and recommendations were made available to the participating businesses
According to the instructors, "Getting behind the scenes, beyond the public facade, was incredible for the students. When you get into the working areas, the utility areas where the electrical equipment is, everything looks different from the images their imaginations had built. It's funny, but the truth is, students cannot identify most of the electrical equipment they have studied, because the real thing is not familiar to them. They've studied what a transformer is, but they can't identify one in the field if it is at all different from what they have in our labs. So when they finally see the inner workings of an electrical system, their entire perspective expands. It's nothing like the lab. The function of the lab components is the same, but students don't have the transferability to field components that can look so dramatically different."
To study an electrical scenario, electrical parameters would ideally be recorded over an extended time period and then averaged to create an accurate big picture; instead, due to time constraints, students connected the instruments and made measurements to create a "snap shot" of the power quality at each location. While this snap shot doesn't necessarily give definitive results of the overall power quality, students could use it to identify potential problems. It was interesting to note that as readings were recorded for the different groups over the course of the day, they varied slightly from group to group. These differences were highlighted back in the classroom, to track the changes for each location and emphasize that power quality problems continually change as electrical loads are turned on and off
Later, back in the classroom, students gathered in small groups to analyze the stored data. They then created Power Point presentations and incorporated actual graphics and analysis capabilities that they gleaned from the test instruments. The students then made group presentations of their findings and recommendations to the entire class, resulting in about 20 power quality analysis presentations. Most of the presentations were of such quality that they could have been presented to a customer, and most of the papers were article-in-a-magazine-good
Success
Was it successful? Yes. For the most interested students, you couldn't pull them off the meters; they wanted to see more and more and more, said one instructor. The experience was successful for 90% of the students, and ideas are being discussed to engage the other 10 percent this year. But, for 25 percent of the students, it was "wet-your-pants exciting," and encouraged them to explore deeper than they would have otherwise.
The experience was so successful, that the next classes of students heard about the project early, and were looking forward to doing it when their turn came. And, more local businesses have been added to the list that will let the classes in to test their service equipment.
For specific information about the Construction Electrician Program at Anoka Technical College, contact Don Clausnitzer, Department Head, at 763-576-4879, or E-mail at dclausnitzer@ank.tec.mn.us.
Related Links:
Project Update Report, Spring 2009: Download (PDF)
