Using PME to detect, measure, and maintain power quality.
By: Allan Evora
Many are intimidated by power quality devices because they don’t feel confident in their ability to analyze power quality (PQ) events/data and determine the proper corrective action. As an industry veteran, I can assure you that the analytical tools today are much more helpful and easier to use when it comes to analyzing power quality within your facility.
One such tool is Schneider Electric's Power Monitoring Expert (PME). When you couple this software with the most advanced line of power meters in the industry, you have a tool that:
- Provides a simple green/yellow/red indication for each type of PQ event monitored in your facility.
- Automatically applies the event to the ITIC curve, providing both a confidence level and impact level.
- Tells you if the event originated upstream or downstream of the PQ metering point. This can be very helpful, especially if the meter is on the utility service entry point in your facility. This tells you whether you need to have a conversation with your utility or your electrical maintenance staff.
Not sure where to start? Here are a few recommendations on things you can do to determine if you want to dig further.
Detecting sags, swells and transients
You’ll want to make your most significant investment installing power quality meters on the electric service entry points in your facility. This area will tell you the most about what is coming in to your facility.
Even if you don't initially invest in software, most meter manufacturers provide free software that allows you to download sag, swell, and transient events from your PQ meter.
Additionally, I recommend you configure a counter and output from the meter that allows you to keep track of how frequently you experience sags, swells, or transients. When setting up the meter initially, you’ll want to use the default IEEE 1159 standards for sag (90% of nominal voltage) and swell (110% of nominal voltage), and 125% of nominal voltage for transient.
If no PQ events are triggered, you can always tighten the tolerance. If you experience a lot of triggered events, you have some work to root cause these events. But the good news is, many events may provide the justification you need for a more sophisticated means for automatically retrieving and analyzing events, such as Schneider Electric's PME software.
Measuring harmonic distortion
All electrical systems have harmonics. The amount of harmonic voltage and current levels a system can tolerate is completely dependent on the equipment you have in your facility and the source of harmonics. While most entry level power quality meters have the ability to report total harmonic distortion within a system, we recommend owners install PQ meters that provide an analysis of the harmonic spectrum. Having an online PQ meter that analyzes the harmonic spectrum can provide validation that your mitigation solution is working.
Some ask, “Why not purchase a portable power quality analyzer instead of installing fixed meters?”
Unless you have a facility that never changes, having an online harmonic monitoring solution can actually support ongoing preventative maintenance and detect problems in the making, eliminating costly failures.
Knowing what your system harmonic levels are, the effect of newly added equipment on these levels, and how much increase in harmonic levels your system can tolerate are valuable pieces of information readily attainable from modern fixed PQ meters.
Maintaining power factor
Even if you don't pay a penalty for poor power factor (PF), it’s a key metric we recommend every industrial facility record, measure, and trend. Remember that power factor ultimately reduces your capacity, which means low PF is indicative of inefficiency. In regards to measuring, it helps that even the most basic digital power meters measure PF.
If you happen to have a very low PF, it can indicate three phase power unbalance which is not good for your equipment. This could be a result of improper wiring and is something you’ll want to correct immediately. If left as is, it will shorten the life of your motors by putting excessive heat and wear on them.
The good news about power factor is that it can be corrected.
For many years capacitor banks have been able to address low power factor. A meter that measures power factor in real-time can also verify the capacitor bank is performing as expected. If it’s not, most meters have on-board communications or a digital output that allows an alarm to be configured whenever the power factor drops below a user defined level.
A more drastic solution might be an equipment replacement strategy, implementing higher efficiency equipment that doesn’t cause drastic phase shifts between current and voltage.
Stay tuned for part 3: Mitigating Power Quality Issues in Industrial Facilities or go back and read part 1: 4 Major Power Quality Issues in Industrial Facilities
Allan D. Evora is a leading expert in control systems integration and president of Affinity Energy with over 20 years of industry experience working in every capacity of the power automation project life cycle. With a background at Boeing Company and General Electric, Allan made the decision to establish Affinity Energy in 2002. Allan is an alumnus of Syracuse University with a B.S. in Aerospace Engineering, graduate of the NC State Energy Management program, and qualified as a Certified Measurement & Verification Professional (CMVP).
Throughout his career, Allan has demonstrated his passion for providing solutions. In 1990, he developed FIRST (Fast InfraRed Signature Technique), a preliminary design software tool used to rapidly assess rotary craft infrared signatures. In 2008, Allan was the driving force behind the development of Affinity Energy's Utilitrend; a commercially available, cloud-based utility resource trending, tracking, and reporting software.
Allan has been instrumental on large scale integration projects for utilities, universities, airports, financial institutions, medical campus utility plants, and manufacturing corporations, and has worked with SCADA systems since the early ‘90s. A passion for data acquisition, specialty networks, and custom software drives him to incorporate openness, simplicity, and integrity into every design in which he is involved.