Widely prevalent power problems include spikes, voltage sags, harmonic distortion, electrical noise and rolling brownouts. Even industries in developed nations equipped with modern power networks are not invulnerable to voltage issues. As modern industry is adopting automation in almost all their processes, the importance of power quality is constantly on the rise. In addition, machinery and equipment may fail or be damaged when power anomalies occur.
Just one or two seconds of a surge or an outage may bring your business to a complete standstill for hours or may be days. Irrespective of the location where you are, surges, spikes, brownouts are issues regularly faced.
Voltage Sag - Definition
Voltage sag is not a complete power loss, it is a drop in power of less than 90% of the normal voltage level. The drop may not be below 50% of the nominal voltage and lasts normally from two to ten cycles or from 40 to 200ms. Voltage sags may be a challenge for large commercial customers and is probably the key power quality problem faced by today’s industrial customers.
The sources of voltage sags are:
- External - on the utility’s transmission and distribution lines
- Internal - within the customer’s facility.
Tree branches may be blown into power lines due to strong winds, connecting the line to the line and the line to the ground. As the branches come into contact with the power lines repeatedly, a series of sags take place.
Flashovers on the insulators may take place because of the formation of ice and snow on power lines. Other external factors affecting the power lines are construction works, traffic accidents and animals. Other reasons for power quality issues may be inside the facility such as incorrect grounding, inadequate building wiring or large loads sharing same circuits.
If the facility is over 15 years old, it's likely it does not meet the requirements of present-day equipment. It is also possible that systems enabling the key functions of your organization may be overloading the wiring and causing failures and power issues that can affect valuable data and equipment.
The Result of a Voltage Sag
Equipment sensitivity, the duration and magnitude of voltage sags will decide whether it will be harmful. The electronic equipment sensitive to voltage sags include motor starter contractors, variable speed drive controls, programmable logic controllers, control relays, robotics and controller power supplies. These items of equipment are typically used in applications that will affect an entire process hence if voltage sags occur, they may prove very expensive.
Table 1 shows the most common reasons of voltage variations.
Table 1. Common voltage problems, the symptoms and 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
(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
||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
||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
To make sure that power quality level is optimized, businesses are deploying power conditioning solutions while planning their facilities. Equipment performance is considerably enhanced while using good power conditioners as it filters and cleans incoming AC power.
Contaminated AC adds wear and tear to power supplies and other internal circuits, but power conditioning solutions improve the life of connected components. Hence a good power conditioner secures equipment from damaging AC events like spikes, surges, high voltage and lighting. The average power strip or surge suppressor is not useful for either protection or to clean and filter contaminated power. ABB power conditioning solutions however, provide excellent protection and low total cost of ownership and are compact. ABBs power conditioning solutions ensure that small, medium and large businesses operate continuously and are protected at a global level.
The PCS100 product line includes low and medium voltage power conversion technology and comprises UPSs, static frequency converters, voltage and power conditioners which show consistent and economic performance. The product line provides effective power conversion solutions developed specifically for solving power quality issues such as voltage sags and to stabilize networks.
ABB features power conversion technology for all applications from data centers to industrial plant protection, shore-to-ship supply and micro grid systems. The range of supply voltages offered is from a few kVA to many MVA.
Benefits of UPS Systems
Most power related problems may be solved using UPS systems. Some benefits of using UPS systems are listed below:
- Continuous power is provided to critical loads in case of an interruption or a complete loss of utility power
- The systems can filter most of the common electrical system disturbances, which interfere with sensitive electronic equipment operation
- UPS systems can enhance the operating reliability of a number of critical building components
- Most of the issues due to disturbances in the utility-supplied power are eliminated
- If the UPS systems are suited appropriately to the requirements of the building, this consistency level is achieved without affecting the budget of the facility.
Identification is the first step in choosing a UPS system. State and local requirements will detect loads crucial to facility operation even at the time of a power outage. Each of these loads are examined to find out which ones will not be able to withstand even a momentary power outage and those that would be damaged in case of power disturbances. Loads not meeting either requirement may be linked to a standby generator system instead. It is important to consider the effect that utility power loss will have on operations, including momentary losses also.
Identify critical loads with regards to power outages or damages from power disturbances. For each load, determine the kind of delay that would result from a momentary outage and how operations would be impacted by that delay. For instance, certain computer-based control systems may take 10mins to reset after losing power temporarily.
Table 2. ABB’s PCS100 portfolio, designed to eliminate and condition power quality issues.
||Utility deep sag and surge correction
Utility outage protection
|PCS100 UPS-I Industrial UPS
PCS100 MV UPS Medium Voltage Industrial UPS
||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
|PCS100 RPC Reactive Power Conditioner
||50/60 Hz conversion
|PCS100 SFC Static Frequency Converter
The load needs to be connected to a UPS if the length of delay for a specific load is not acceptable.
The Need for Voltage/Power Conditioning not Back-up Power
Several businesses need power or voltage conditioning instead of UPS systems. In cases where there is no need for backup power, excellent protection is offered with a voltage conditioner. These devices offer voltage regulation and further power quality- related functions such as voltage fluctuations, over/under-voltage, sags and dips, short circuits, line noise and swells, phase imbalance and brownouts and surges.
In order to attain a reliable power protection solution, businesses can adopt several power conditioning systems particularly in large energy user situations. At present, voltage conditioners are used along with UPS units to extend UPS capabilities and improve UPS efficiency, to secure the UPS, condition the UPS bypass and protect HVAC systems.
Power quality issues can occur anytime anywhere. These issues may range from total damage or premature failure of equipment to randomly malfunctioning equipment. The real issue with poor power is damaged equipment cost, scraps, lost productivity or missing schedules. Implementing power conditioning systems will enable business to overcome common power quality issues and attain high production output and secure critical operations from failing.
About ABB Power Conditioning - Discrete Automation and Motion Division
ABB is a leading supplier of UPS and power conditioning products – ABB's PCS100 portfolio is a unique line up of low and medium voltage power conversion technology. The PCS100 power converters demonstrate highly reliable and cost-effective performance. With the PCS100 product portfolio, ABB offer efficient power conversion solutions that are specifically designed to solve power quality problems and stabilize networks. Covering applications from data centers through to complete industrial plant protection, microgrid systems and shore-to-ship supply, ABB have the power conversion technology for every need. Starting from a few kVA to many MVA and a wide range of supply voltages. ABB has installed more than 900 MW of power conditioning solutions worldwide. It’s business as usual with ABB Power Protection.
This information has been sourced, reviewed and adapted from materials provided by ABB Power Conditioning - Discrete Automation and Motion Division.
For more information on this source, please visit ABB Power Conditioning - Discrete Automation and Motion Division.