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The hidden cost of poor power quality

Frank Healy Fluke Power Quality Product Marketing Manager

(BOM) Hi, I’m James Pease and this is Take 5, Building Operating Management’s podcasts on topics of interest to building and facility executives.

If you have power quality problems, your biggest financial loss will likely be in the area of production. We tend to think of production in a manufacturing sense and, obviously, if the assembly line shuts down, production stops cold. But ‘production’ is the result of whatever work is being carried out on a site. It might be serving customers in a supermarket or carrying out bank transactions. Or, of more serious consequence, it can be caring for patients in a healthcare facility. Whether merely inconvenient or life-threatening, business disruption caused by power loss or equipment failure is clearly something to be avoided if possible.

With us today to discuss power quality problems and solutions is Frank Healy, Power quality Product Marketing Manager with Fluke, the leading manufacturer of electronic test tools and software.

Thanks so much or being here with us, Frank.

What are the clues that there might be a hidden problem in an electrical system?

(Healy) You may have power quality problems on a site without actually realizing that there is a problem. These problems can manifest themselves in many ways - a really common way is the circuit breaker that trips occasionally but there doesn’t appear to be a clear reason why it happened. Another example is where a particular piece of equipment keeps failing, you might suspect the equipment is faulty and replace it only to have another failure. And a particularly annoying symptom is where equipment resets and causes a process failure. These are just a few of the symptoms, there might be other variations of these that aren’t clearly recognized as being caused by poor power quality.

(BOM) I can see how chasing phantom problems is aggravating – especially in complex systems – and needlessly replacing suspect equipment is expensive. What other potential 'costs' are there if these problems go undiagnosed?

(Healy) As you said, production loss is the biggest cost where you have power quality problems, and that, of course, translates directly into financial losses. There are many estimates of the losses caused by power quality issues and although the estimates vary, it seems to be in the hundreds of millions of dollars per year for US businesses. Whether you are a building owner or facility manager you have the responsibility of ensuring your tenant or customer can effectively carry out their day to day business. If you can’t provide the level of service they need you’re going to end up in a very unhappy situation.

(BOM) What’s usually the source of these problems, Frank?

(Healy) Often when a power quality problem is being considered people think the power utility is most likely to blame. Unfortunately things aren’t that simple. There are some problems that might be considered the responsibility of the utility but most often power quality problems originate inside the facility. The most common problem are voltage dips. These are changes in the voltage that can easily be caused by equipment inside the facility such as elevators or the motors on water pumps. When this type of large equipment starts, the current drawn causes a reduction in voltage. Sometimes this voltage reduction can affect other sensitive loads such as computer equipment causing it to reset. Of course it might not be obvious that the two things coincide and it might only be in exceptional circumstances when the dip has a serious affect. Another common problem experienced is overheating transformers and wiring caused by harmonics.

(BOM) Harmonics? Could you explain that?

(Healy) Harmonics are produced by "non-linear" loads in power systems. A non-linear load doesn’t draw current in proportion with the applied 60 Hertz sinusoidal voltage waveform. In other words, this equipment "gulps" electric current from the supply rather than taking current in a smooth fashion. Harmonic-producing non-linear loads come from devices with power electronics like computer equipment, ASDs – that means adjustable speed motor drives - and electronic lighting ballasts.

Harmonics have been known to burn out neutral conductors so they’re a very real safety concern too.

(BOM) OK, so what can I do about poor power quality?

(Healy) There are many things that can be done to either find or prevent power quality problems. Prevention should be considered the best option. Many power quality problems can be prevented by careful planning of the installation of potentially polluting equipment, keeping that equipment on circuits away from more sensitive loads. Ensuring installations are correctly designed to electrical code is extremely important. During the development of electrical codes, power quality has been given serious consideration so using code recommendations ensures the potential for problems is reduced.
For older installations, or certain types of loads, sometimes power quality mitigation must be considered. If this is the case the first step must be to identify and quantify the problem. This can be done by making power quality measurements using a power quality analyzer. To get a clear picture of what’s happening on an installation the equipment should measure over a typical operating period, say a day, or even better a week. By measuring over this period of time you can start to understand the different circumstances that may occur. Using this information you can start to understand what’s happening. The problem could be solved simply by moving a polluting load to another circuit. Or it might be necessary to install equipment to minimize the problem. The types of equipment that you might consider are voltage stabilizers, which give a constant output regardless of the input voltage, or UPS (uninterruptable power supply systems), which continue to supply power even if main power is lost by using a back up battery. In some cases filters have to be installed to reduce harmonics, in this case you will need to work closely with your filter supplier as the selection and design of the filter is a very specialized task.

(BOM) Alright. And looking down the road, how can we prevent power quality problems developing in the future?

(Healy) As I’ve already mentioned planning is the key. Always consider where you will site particular loads, consider what equipment might be sensitive and which equipment might cause problems. Use electrical code to design circuits that have a good chance of working without a problem. Be proactive and make power quality measurements from time to time so you can find a small problem before it turns in to a big one.

(BOM) If someone isn’t that familiar wth power quality issues, where can they go to learn more about it?

(Healy) The website www.HiddenPowerProblems.com has some really great information on it from application notes to videos. It customizes the information you get based on your experiences so if you’re new to power quality you can start with the basics or if you’re more experienced there is information that will suit you too. There are also some great on-line tools like the Power Problem Solver, that start with the symptom or problem you are experiencing and walk you through to the best tools to find the solutions.

(BOM) Thanks so much for spending this time with us, Frank, and the great information.

Our guest today has been Frank Healy, Power quality Product Marketing Manager with Fluke. For more information on how you can diagnose and solve your power quality problems, visit www.HiddenPowerProblems.com or click the link on this page.

Thanks for listening to Take 5.