How to Tackle and Fix Voltage Problems

Table of Contents

What is a Voltage Sag?
The Result of a Voltage Sag
How to Tackle These Issues
I Need Back-Up Power
I Don’t Need Back-Up Power
Combining Solutions for Optimal Performance


Rolling brownouts, electrical noise, spikes, voltage sags, and harmonic distortion. If you haven’t experienced any of these power problems yet, you will. In the present market, using the power from a local utility cannot be taken for granted. The increasing use of microprocessors in office equipment, appliances, and process controls has made us all aware of power quality demands from equipment and the environment, and the irregularity of its supply.

Industry in developed countries with latest power networks is not insusceptible from voltage problems. Although utilities try their best to supply reliable, excellent power, reducing total outage events, periodic sags and surges on utility lines will remain a fact of life. With the current industry using a lot more automation, the sensitivity of processes to power quality events is growing. Moreover, machinery and equipment can be damaged or even fail when exposed to power anomalies. One or two seconds of outage or a surge can cause business to go down for hours or days. No matter where the location is, spikes, brownouts, surges, and other power issues are probable problems.

A number of businesses now understand that power is not an infinite resource. Part of the issue that utilities face is that they cannot generate adequate power to supply increasing needs, and it can take years to construct more power plants.

What is a Voltage Sag?

A voltage sag is not a total interruption of power, but a temporary drop below 90% of the minimal voltage level. A majority of voltage sags do not fall below 50% of the minimal voltage, and they typically last from two to 10 cycles or from 40 to 200 milliseconds.

Voltage sags are perhaps the most substantial power quality problem facing industrial customers at present, and they can be a major issue for large commercial customers as well. There are two sources of voltage sags: internal, within the customer’s facility, and external, on the utility’s transmission and distribution lines.

Tree branches can fall onto power lines during high winds, connecting the line with the ground and the line to the line. A series of sags will happen as the branches repetitively touch the power lines. Snow and ice pile-up on power lines can cause flash overs on the insulators. Other external causes are construction works, traffic accidents, and animals impacting the power lines.

While utility power can be volatile, what happens within a building can also be a disaster with business’ operations. In addition to external environmental factors impacting power quality, a range of other issues are caused within a facility – from insufficient building wiring or incorrect grounding, to large loads sharing the same circuits. These issues can be compounded by starting, running, and stopping large machinery and other business-critical systems. If the building is over 15 years old, it probably was not designed to match the demands of present day high power equipment. The systems supporting the key functions of an organization may be overloading the wiring and causing power issues and failures that can harm valuable equipment and data. Even a short event of a few milliseconds can result in processes suddenly stopping, potentially resulting in product wastage, damage, and production shortages.

The Result of a Voltage Sag

Whether or not a voltage sag creates a problem will depend on the duration and magnitude of the sag and on the sensitivity of equipment. Several electronic equipment are sensitive to voltage sags, including motor starter contactors, variable speed drive controls, controller power supplies, programmable logic controllers, robotics, and control relays. Most of this equipment is used in applications that are essential to an overall procedure, which can cause expensive downtime when voltage sags happen.

Utilities constantly aim to provide the most dependable and consistent electric power possible. In the course of normal utility operations, however, a number of things can cause voltage sags. The most common causes of voltage inconsistencies are shown in Table 1.

Table 1. Common voltage problems, the symptoms and causes

Voltage Disturbance Typical Symptoms Typical Causes
Sags and Swells Shrinking computer displays (the image doesn’t fill the whole screen) or lights that are overly bright or dim Brief reductions or increases in voltage that occur when a major appliance or other piece of equipment switches on or off

A short circuit
Transient Voltage
(also known as impulses or spikes, these problems occur when there are sudden increases in voltage)
Processing errors, data loss or burned circuit boards Lightning strike

Starting or stopping major equipment
Radio/Television Interference Loss of radio/television reception

Poor-quality sound or picture that is interrupted by static

Popping sounds, crackles, rolling horizontal lines, wavy lines, snow, ghosting or other reception problems
Signals from other equipment, usually within your home or building or that of a neighbor

Possible home sources include doorbell transformers, toaster ovens, electric blankets, ultrasonic pest controls, fans, refrigerators, heating pads, light dimmers, touch-controlled lamps, fluorescent lights, aquarium or waterbed heaters, furnace controls, computers or video games

At times, the interference may be generated by utility equipment, such as loose hardware, or dirty or damaged insulators
Harmonic Distortion Appliance or equipment problems, such as communication errors, overheating or electrical hardware damage Certain electronic equipment, such as computers, monitors, and laser printers, video games, touch-controlled lamps and fluorescent lights, may use electricity in a way that causes distortion of the normal electrical wave pattern

Contrary to popular belief, harmonic distortion is not caused by a utility company sending out distorted electrical current


How to Tackle These Issues

Current businesses are implementing power conditioning solutions into their facility plans, so as to ensure that power quality is at a good level. A good power conditioner will filter and clean incoming AC power and dramatically enhance equipment’s performance. Power conditioning solutions will boost the longevity of connected components, since contaminated AC causes wear and tear to power supplies and other internal circuits. Thus, a good power conditioner protects the equipment from damaging AC events such as surges, lightning, spikes, and high voltage.

The average surge suppressor or power strip provides only little protection and does not filter or clean contaminated power at all. However, ABB power conditioning solutions always provide the lowest total cost of ownership and highest level of protection, and at the same time as have a small footprint in design. Guaranteeing the constant operation of medium and small to large businesses is what ABB’s power conditioning solutions do best.

The PCS100 portfolio is a unique series of medium and low voltage power conversion technologies comprising of UPSs, static frequency converters, and voltage and power conditioners that determine highly reliable and cost-effective performance. The product portfolio provides efficient power conversion solutions that are precisely designed to resolve power quality issues, such as voltage sags, and stabilize networks.

Covering applications from data centers through to fulfill micro grid systems, industrial plant protection, and shore-to-ship supply, ABB has the power conversion technology for all needs, beginning with a few kVA to many MVA and a broad range of supply voltages.

I Need Back-Up Power

UPS systems provide a reliable solution for a broad range of power-related issues. These systems can offer constant power to critical loads in the event of a stoppage or a complete loss of utility power. Moreover, the systems can filter out a number of the common electrical disturbances that hinder with the functioning of sensitive electronic equipment.

UPS systems provide a means to improve the operating reliability of important building components. They can remove many of the issues caused by disturbances in utility-supplied power. They can also allow for sustained operation when utility power is down. And as long as systems are correctly matched to the building’s needs, they can offer this level of reliability without costing much.

Identifying the requirement is the initial step in choosing a UPS system. Local and state needs will instruct certain loads that are important to the operation of the facility, even during a power outage. Each of these loads should be examined to establish which ones cannot endure even a brief outage in power, as well as those easily damaged by power instabilities. Loads that do not match either requirement can be coupled to a reserve generator system instead.

For each load, the effect of the loss of utility power on operations, including temporary losses, should be considered. Loads that are important with regard to damage from power disturbances or power outages should also be identified.

For each of these loads, define what type of delay would occur during a momentary outage, and how that delay would affect operations. For instance, some computer-based control systems may take as long as 10 minutes to reset after a momentary loss of power.

If the length of the delay for a specific load is undesirable, that load is a candidate for connection to a UPS.

Table 2. ABB’s PCS100 portfolio, designed to eliminate and condition power quality issues

Product Line Typical Applications Product
Industrial UPS Utility deep sag and surge correction

Utility outage protection
PCS100 UPS-I Industrial UPS

PCS100 MV UPS Medium Voltage Industrial UPS
Voltage conditioning Utility sag and surge correction

Load voltage regulation
PCS100 AVC-40 Active Voltage Conditioner for sag correction

PCS100 AVC-20 Active Voltage Conditioner for voltage regulation
Reactive power conditioning Load created sag correction

Power Factor correction

Harmonic mitigation

Unbalance correction
PCS100 RPC Reactive Power Conditioner
Frequency conversion 50/60 Hz conversion

Frequency fluctuation
PCS100 SFC Static Frequency Converter


I Don’t Need Back-Up Power

A number of businesses require power or voltage conditioning rather than battery back-up power. In those cases where back-up power is pointless, a voltage conditioner can offer excellent protection. These devices offer voltage regulation and one or more extra power quality-related operations, such as voltage fluctuations, protecting against over/undervoltage, sags and dips, phase imbalance, line noise and swells, brownouts, short circuits, and surges.

Combining Solutions for Optimal Performance

Businesses can also adopt a combination of power conditioning systems to facilitate a more sturdy power protection solution, particularly in large energy user situations. Currently, voltage conditioners are also used along with UPS units. Using voltage conditioning, in combination with UPS, offers improvements such as increasing UPS efficiency, extending UPS capabilities, conditioning the UPS bypass, protecting the UPS system, and protecting HVAC systems.

Power quality issues can happen anytime, anywhere. Evidence of these issues can be as clear as electrical components that are damaged or fail prematurely, or as subtle as equipment that randomly breaks down. However, the real issue with poor power is the cost of damaged equipment, scraps or missed schedules, and lost productivity. Implementing power conditioning systems will help businesses override usual power quality issues, accomplish increased production output, and protect important operations.

This information has been sourced, reviewed and adapted from materials provided by Innovative ABB Power Conditioning - Discrete Automation and Motion Division.

For more information on this source, please visit ABB Power Conditioning - Discrete Automation and Motion Division.

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