Power quality problems that affect sensitive and critical equipment include poor grounding, momentary voltage fluctuations and continuous harmonic distortion. When power quality is suspected to cause equipment to malfunction the first steps often include understanding the power problems that need to be solved, or conversely, confirming that the power is adequate and eliminating power quality as a potential cause.
When we develop an understanding of the equipment and application we can often determine an appropriate resolution non-intrusively. In some cases, however, we need to connect power quality recording monitors (PQMs) or other test equipment and gather data for analysis. Touchstone has extensive experience connecting and operating PQMs and analyzing data. Too often, technicians connect PQMs at the wrong points, set up PQMs incorrectly, or are not capable of effectively analyzing recorded data.
Most modern electronic equipment operates very well with voltage that is less than perfect but within a wide range of limits. A significant amount of harmonic voltage distortion is relatively harmless. Separate, exotic grounding systems are rarely required and often contribute to equipment malfunction or introduce safety risks. But severe situations require remedies. More often, it’s not a power quality problem, it’s a power continuity problem, a total or near-total loss of voltage for a fraction of a second or longer. To solve power continuity issues, energy storage, typically in the form of batteries (UPS systems) or alternate or redundant power sources (onsite power generators, fuel cells, micro-grids, etc.) are often required.
Design engineers sometimes overdesign for perceived power quality issues. This not only results in unnecessary added cost (upfront and ongoing maintenance) but can cause other problems. Capacitive elements in power filters, in particular, can over-compensate and cause wild voltage fluctuations, or resonance that nuisance trips circuit breakers or leading power factor that affects generator voltage regulators. Standard transformers that would perform very well when properly sized, that are instead specified for high-harmonic load K-factor ratings can result in long lead times and double the cost.