Power Quality
Power Quality (PQ) is the quality of the voltage, including its frequency and the resulting current, that are measured in the Distribution System during normal conditions – periods where there are no typhoons or supply deficiencies. PQ is all about electromagnetic compatibility or when equipment or appliances will be able to operate satisfactorily without supply disturbances.
Poor PQ can greatly impact the overall safety and day-to-day management of your business. Maintaining an ideal level of PQ should be prioritized in your operations to:
- Avoid power interruptions for your business
- Prevent production and business opportunity losses due to power interruptions
- Prevent early deterioration of equipment and extend service life
Abnormal conditions of weather and environment such as rain, thunderstorms, lightning, landslides, or any natural disaster all pose a hazard to PQ. Accidents arising from these faults, interruptions and disturbances may lead to damaged equipment and poles, and broken distribution lines. Even animals like snakes, birds, and squirrels may disrupt PQ.
Power quality problems that cost customers significantly in terms of energy waste, damage to equipment, and facility downtimes or shutdown point to these common issues:
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Voltage Mismatch
To understand voltage mismatch, let’s use an analogy. Imagine you are going on an off-road drive. What car will you use: A four-wheel drive jeep or a sports car? Considering the terrain, you will probably opt for a four-wheel drive to ensure the vehicle and its passengers are safe.
Similarly, when it comes to power, you need to ensure the equipment used in your business is matched with the kind of power being supplied. If not, this will result to a voltage mismatch.
Voltage Mismatch can lead to problems like the motor failure, device malfunctions or worse, your factory / plant shutting down.
To avoid voltage mismatch, you can do the following:
- Be aware of Meralco’s standards as mandated by The Philippine Distribution Code and match these with the equipment of your business.
- If your equipment requires other voltage levels, use a transformer to ensure compatibility with the power supply.
- When purchasing equipment, ensure that the voltage variation is within the allowable range.
- Be aware of Meralco’s standards as mandated by The Philippine Distribution Code and match these with the equipment of your business.
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Voltage Unbalance
Customers with a three-phase system need a balanced three-phase voltage not only to enable the operation of their equipment but also to operate their equipment efficiently. In three-phase services, voltage unbalance may occur when single-phase electrical loads are unevenly distributed across phases or when there is a single-phase outage. This voltage unbalance can cause increased heating in three-phase motors and reduce their efficiency.
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Voltage Sag
A voltage sag or voltage fluctuation is a decrease in Root Mean Square (RMS) voltage between 10% to 90% of the nominal value for time greater than half a cycle (typically in milliseconds) but not exceeding 1 minute. Commonly you experience flickering of lights when there is a voltage sag. This can be caused by switching on electrical motors or large loads, or any fault on either distribution, transmission or generation systems.
Reasons for Voltage Sag
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Line-to-Ground / Line-to-Line Faults on the Utility System due to:
Weather
Trees
Public Interference
Animals -
Internally included plant events (starting of large inrush load)
Although the utility can reduce the number of events (tree trimming, root cause analysis) it is impossible to eliminate all voltage sags.
While not ideal, voltage sags are an unavoidable aspect of Meralco’s electrical systems. Any impact sags may have on a customer's consumption depends largely on its magnitude and duration and the sensitivity of the customer’s equipment.
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To maintain proper Power Quality, Meralco regularly implements regular upkeep of its distribution lines and equipment. Some examples include:
- Thermal scanning to detect and correct any components that have overheated.
- Pole ground resistance testing for protection from excessive energy induced from lightning.
- Regular tree trimming to prevent power interruptions caused by electric lines caught in tree branches.
- Distribution (DT) Load Testing which checks if distribution transformers serving customers are within the range of efficient loads. If an overload is found, the contracted capacity of the customer is reviewed to see how this can be corrected.
- Pole inspection to see if there are any defects or abnormalities that need replacement or correction.
- Installation of animal deterrents on electric poles / lines to prevent power interruptions caused by birds, snakes or other animals.
A better supply allows for quality power to be safely delivered to businesses. Some measures Meralco has taken to do this are:
- Installation of overhead shield wire and other line maintenance activities to prevent power interruptions due to lightning, thunderstorms or other events that may affect supply.
- Adjustment of the DT Tap Changer.
- Conduct of voltage studies in areas with issues to assess the need to install Automatic Voltage Regulators (AVRs) that can further improve the voltage along the distribution lines.
- Conversion of bare overhead lines to covered overhead lines to address transient contact due to trees, vegetation, animals, or construction or renovation of buildings.
- Installation of fiberglass crossarms which prevent line-to-ground fault caused by animals resting on electric poles.
Managing PQ Distribution is a responsibility shared by Meralco with its customers. Here are measures that customers can implement for their business:
- During the design and planning stage of your business, be sure your equipment is compatible with the rating and tolerance of voltage supply from Meralco to avoid voltage problems. It is best to consult us before investing in sensitive and costly equipment to avoid losses/unnecessary expenses.
- Observe proper wiring and grounding.
- Choose and implement solutions to protect your facility from power quality problems:
- Segmenting your facilities according to the criticality of the loads (i.e., non-critical loads, sensitive loads, critical loads). If some identified electrical equipment are sensitive to short-term power disturbances, consider installing appropriately sized power conditioning devices, like an Uninterruptible Power Supply (UPS) or Sag Corrector, to limit the effects of these disturbances on operations.
- Ensure that internal voltage levels are compatible with the needs of your equipment and systems by installing an Automatic Voltage Regulator (AVR).
- Limit excessive load swings that negatively affect power quality to your facility and/or other customers.
- Limit injection of harmonics into the utility distribution system by installing a Harmonic filter, especially if there are manifestations of harmonic issues.
- Conduct Power Quality analysis to understand the vulnerability of your equipment and to determine the exact nature of any problem. DOE Accredited Energy Services Companies (ESCO), such as MServ can be tapped for such a requirement.
To learn more about how PQ affects your business operations and how we can help you address it, you may email us at biz@meralco.com.ph, call our business hotline 16210, or get in touch with your Biz Partner Manager.