Facing power quality (PQ) problems head-on requires facility engineers and managers (FEMs) first to find out if a PQ problem exists, and — if it does — then how it is affecting the plant’s operations. The key question that must be answered is, “What is the financial impact on the company?” This question must be answered with a reasonable amount of accuracy.
Understanding how to determine the financial impact and identify the factors creating the problem is critical when it comes time to invest in understanding, identifying, solving, and preventing (UISP) PQ problems. Since PQ problems can affect the entire plant operation, it is understandably difficult for plant managers to determine, document, and appropriately absorb their financial impact and the factors that make it up.
The financial impact and varying factors that make up the true cost of PQ problems are referred to as “PQ economics.” Here are examples of the financial effects associated with PQ issues:
Fines for delivering products and/or services to plant customers late may significantly impact plant profits and performance.
- Products and/or services for the plant’s customers may be delayed.
- Products may be defective or damaged during production.
- Production and/or plant support equipment may have malfunctioned rendering it unavailable or may have been damaged or experienced failure,
- Costs to repair, rent, or replace a piece of equipment may not be known before PQ problems occur.
- The costs to reprogram a piece of equipment may be unknown.
- Critical data lost from memory inside a piece of equipment may not be reproducible.
- Raw materials planned for use and/or products planned for shipping may be discarded as waste.
- Parts inventories required to produce final assemblies may be delayed and unavailable when needed.
- Permanent and/or contracted labor may not be able to fulfill their production duties if any of the above occurs.
- Additional labor needed to overcome production equipment problems is not anticipated.
- Costs to continue the operation of a partially functional plant to preserve and/or protect products may be unknown.
- Costs to hire and engage a crew to clean up part or all of a plant may be unknown.
- Costs to restart, reset, and/or recalibrate a piece of equipment or plant process may be unknown.
- No one person in the plant is formally trained on how to determine PQ economics.
- Understanding and identifying these costs require extra time on the part of multiple people in the plant.
Experts in PQ have been examining the cost of PQ problems for more than two decades. Many organizations, such as the U.S. Department of Energy (DOE), Electric Power Research Institute (EPRI), and Centre for Energy Advancement through Technological Innovation (CEAtI), as well as solutions providers (including PQ monitor manufacturers and software companies that develop/sell PQ data analysis software) have been working to unravel PQ economics and PQ mitigation equipment manufacturers. The work done by these organizations have paved the way for a better understanding of how PQ problems impact the financial performance of customer’s operations — both commercial and industrial.
This article seeks to help FEMs understand and identify the cost factors resulting in the total financial cost (TFC) of experiencing a PQ problem.
Understanding & identifying the cost factors
Before the TFC of experiencing PQ problems can be determined, FEMs must understand the cost factor groups (CFGs) containing the cost factors (CFs). These factors, arranged in groups, allow FEMs — with the help of PQ experts — to determine how the variability of their plant operations affects the overall TFC of PQ problems. Knowing how to calculate the EFTC is not a critical part of determining your PQ economics. Identifying and documenting the CF data requires more effort and is critical before the EFTC can be determined. Almost all of the CFs that are determined are real documented data — the exact TFC cannot be determined. Since nearly all of the CFs can be based on actual financial data, the estimated TFC (ETFC) is the end result that can, be used to determine the economic impact of PQ problems with confidence.
Cost factor groups (CFGs)
The Table lists the four CFGs needed to determine the ETFC. The number of CFs per CFG and the description of each CF is defined.
A PQ event that impacts a plant may be caused by a grid-related event (GRE), a plant-related event (PRE) that was caused by something that happened inside the plant, or both. GREs and PREs are caused by electrical disturbances.
In many cases, a GRE will cause a PRE to occur. This sequence of events occurs because one or more wiring and/or grounding problems (WGPs) exist inside the PES. WGPs can magnify disturbances causing E/EE equipment to malfunction, experience damage, or completely fail. WGPs can also cause overcurrent conditions within the PES that can cause overcurrent protection devices (OCPDs) to operate and/or PES components (e.g., electrical cables, dry-type transformers, etc.) to fail.
GREs may be the result of normal operations [e.g., a recloser operating because a tree limb came in contact with an overhead line (OHL)] on the electric utility transmission system and utility distribution system. Objects coming in contact with OHLs and underground lines (UGLs) are GREs that create faults (i.e., fault currents) to flow on the electric utility power system. Another example of a normal electric utility operation is lightning striking an insulator on a transmission tower that causes a substation breaker to operate.
Regardless if the event is a GRE, PRE, or both, a plant will experience one or more PQ problems that will likely impact the PES and the E/EE (loads). Because plant loads are always dynamically changing, the state of the PES is also constantly changing as well as the susceptibility (immunity) of the PES and its E/EE to disturbances. Thus, a GRE and/or PRE that occurs at a specific date and time that causes a specific PQ problem (tripping of machine 1) to occur can cause a different PQ problem (tripping of machine 2) to occur, even if the second event is exactly the same as the first event. The cost of these two events (the tripping of machine 1 and the tripping of machine 2) can be different. One can see why it is critical to document the CFs when machine 1 trips as well as when machine 2 trips. The ETFCs of the two events will also likely be different.
The EFTC must be known before the cost to mitigate a PQ problem, and the return on investment (ROI) can be determined. My next column will expand the discussion of the PQ economics calculator (example shown in Figure) and provide the CFs from some real-world cases of PQ problems in commercial facilities and industrial plants to determine the effects of the CFs on ROI.
