Power Quality and Accuracy: Why Not all Meters are Created Equal
- Apr 3, 2019 2:15 pm GMT
- 1892 views
Measuring the quality of your power is a necessity for maintaining reliability, meeting compliance requirements and avoiding costly issues before they occur.
But with the growth of renewable and distributed energy generation, measuring power quality has become more challenging.
Not all meters are created equal and adding the capability for measurement of the quality of the electrical power can directly affect meter selection. Only a few are suitable for measuring grid power quality.
With modernized electrical systems and digitized equipment, the need for power quality instruments is even greater. The new model of utility power distribution has expanded from centralized generation to include renewables. This can change the electrical signatures flowing in the system, creating an even more urgent need for accurate and reliable power quality measurements, and at more points throughout the distribution network.
Another factor driving the need for reliable power quality measurements is the digitization of electrical metering. While many meters can report on power quality, there is a wide spectrum of how comprehensive and how accurate the power quality measurements are. And metering devices and their measurements can differ significantly depending on the manufacturer.
IEC power quality measurement standards
When choosing a power quality instrument, it is important to understand IEC requirements for this type of equipment. IEC 61000-4-30 is a standard that has been around since 2003 and one that most reputable manufacturers of power meters today comply with.
However, it focuses primarily on power quality measurement methods but does not address the need for a standard process to verify the implementation of IEC 61000-4-30 compliant power quality measurements.
As a remedy, the IEC recently created the two-part IEC 62586 series of standards. Part 1 (IEC 62586-1) defines a comprehensive PQ device product standard, known as PQIs. It outlines safety, electromagnetic compatibility (EMC), climatic, and mechanical requirements, all to ensure the tool is suitable for installation within the often-severe environment of a power station or substation.
Part 2 (IEC 62586-2) defines the functional tests, procedures, and conformance levels intended to verify compliance with the PQ measurement methods specified in the 4-30 standard. This addresses the main shortcoming of the original 4-30 standards, and ensures manufacturers conform to the same specifications.
Not only is there a need for accurate measurement, but of all possible issues, which as you can see from the IEC 61000-4-30 list of PQ metrics covers a lot of ground:
• Power Frequency
• Voltage Magnitude
• Dips, Swells & Interruptions
• Voltage Unbalance
• Voltage Harmonics
• Voltage Inter-harmonics
• Mains signaling
• Clock uncertainty
• Influence quantities
• Rapid voltage changes (RVC)
• Current Magnitude
• Current Harmonics
• Current Inter-harmonics
• Current Unbalance
Choosing the right power quality instrument is crucial for successful measurement of power and adherence to standards. Download the white paper Power Quality Instruments (PQI) An Overview to understand what to look for in a power meter.
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