Learn how power and power quality can affect equipment within a plant

Jan. 19, 2022
Power disturbances can be difficult to identify and affect performance in precision equipment.

As asset maintenance and reliability professionals well understand, equipment issues are not always what they seem, especially with precision instrumentation and inspection equipment. Often they are a result of something unseen: power quality. In order to keep valuable equipment operating as it should, and for its intended lifespan, this invisible variable must be considered carefully.

About the Author: Charles Carroll

To fully understand how power and power quality can affect equipment within a plant, there are a few questions that must be answered. Where do power problems originate? What can happen if these problems go unaddressed? What solutions are necessary to alleviate these issues fully?

Where do power problems originate?

One of the most recognizable power-related events are blackouts caused by power surges that knock out electrical systems in a big, sweeping hit. These types of events are abrupt and very noticeable, so most people are aware of their occurrence. Unsurprisingly, it is these types of events that the majority of the industry thinks of when the subject of “power issues” is brought up. According to estimations from industry experts however, these dramatic events are far from the only causes of power issues. While they may be severe, they are not the norm or even the main culprit for power problems.

The majority of day-to-day power issues actually originate from within a facility in the form of electrical noise like electrical impulses, high-frequency noise, and high-voltage transients. This phenomenon originates from everything within a facility that runs on electricity, whether that be a piece of manufacturing equipment, computer systems, the building’s HVAC systems, and even overhead lighting, and therefore cannot be stopped at the source because these components are necessary to daily operation. All this noise must instead be dealt with prior to the power it affects arriving at the machinery it needs to drive.

What happens if power problems go unaddressed?

Power issues like noise and transients lead to variance in power quality. To illustrate how this works in a graphical sense, consider that clean power flows in a sine wave. Power problems appear as sags, swells, or spikes in that wave. The more advanced and finely-tuned the electronics equipment, the more susceptible it is to even the smallest of power disturbances, so these blips are a big deal. Power variance can easily disrupt sensitive manufacturing equipment in a way that can be hard to detect in real-time. Over time, the life-span of critical components may be compromised, resulting in sub-optimal performance or accuracy. None of these issues happen in isolation – problematic power environments affect every machine running on electricity. This means that it is not one performance blip on one machine. It’s hundreds, or thousands, every day across all devices and it is these accumulated impacts that can be felt in the margins.

Tactics and Practices

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Seemingly anomalous errors that lead to “no trouble found” service calls are frequently the result of such power disturbances. These mysterious performance issues often result from what is called “disruption,” whereby power disturbances corrupt logic signals, which alter digital output and lead to software bugs. Other issues include destruction, which is caused by power surges, as well as degradation, which is caused by low-amplitude power disturbances that erode semi-conductors and lead to thermal runaway. These issues can cost your company money in the form of replacement components and additional equipment servicing. Plant managers would be wise to recognize the risk of these disturbances, even if they cannot always see the causes.

While you might assume that costly equipment is built to handle a bit of wear and tear, this is decidedly not the case with highly calibrated, sensitive manufacturing equipment. These machines are designed and tested to perform highly under specific circumstances, but when circumstances change, so does performance. This is an issue that legacy power protection products like surge protectors and backup generators aren’t equipped to address.

What solutions are necessary to alleviate these issues fully?

For large medical, commercial, or industrial applications with sophisticated, high-usage electrical machinery, surge protectors and backup generators simply do not cut it. Surge protectors are designed to divert surges (the high-voltage transients or impulses discussed above) away from the sensitive electronic systems they protect. Though useful, this does not eliminate the impulse, which means the power problem persists and the system strains. Backup generators meanwhile are designed to keep your most essential equipment running in the event of an outage, but what if all your equipment is essential? A backup generator is not as productive or reliable as regular power from the grid, so it will be forced to prioritize where its power is diverted. Another major drawback is that a generator can take up to 45 seconds to start up and supply power, an eternity to unprotected sensitive systems. Either way, this is less than ideal – especially when considering that a traditional backup generator does not provide power conditioning when not actively in use.

Fortunately, more robust solutions exist. A majority of commercial-level power protection solutions now deploy a surge diverter, noise filter, or both, but the most important element of power protection is actually a low impedance isolation transformer. This specialized feature acts to isolate the powered instrument from the power source and re-establishes the neutral-ground bond without opposing or disrupting the current path. The device is then truly protected from unwanted noise without negatively affecting power flow.

In large applications, these conditioners are integrated into uninterruptible power supply (UPS) units, which deliver reliable, clean, and uninterruptible power even in the event of a blackout. Leading UPS models also include an internal maintenance bypass system, customizable power distribution units (PDU), wide input voltage range, and integrated simple network management protocol (SNMP) capability. Some even feature hot-swappable batteries to allow the unit to stay online during maintenance. An additional and highly beneficial element of a sound UPS system is that it provides a central, clean grounding point for all components.

At the end of the day, power protection is about proactively mitigating and managing the risk to equipment from power-related failures including performance degradation, erosion of sensitive conductors, components, and circuits from low-amplitude power disturbances and surges. Asset maintenance and reliability professionals managing plant equipment cannot wait for electrical issues to happen – they need to be proactive. Acknowledging the potential issues and identifying the solutions are the first steps in doing that.

This story originally appeared in the January 2022 issue of Plant Services. Subscribe to Plant Services here.

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