What to consider when choosing a power quality meter
CONTROL & AUTOMATION BEYOND THE 50TH HARMONIC
CPA LTD
What to consider when choosing a power quality meter
The Engineering Recommendation G5 / 5 has extended the values for planning and compatibility levels to the 100th order ( 5 kHZ ), but most power quality measurement and mitigation devices are yet to catch up . Because most metering devices still work to the old standard of 2.5 kHz ( 50th order ), these cannot provide a complete picture of the spectrum — leaving engineers in the dark . So , how can operators ensure they choose the right meter ? John Mitchell , global sales & marketing director at CP Automation , explores .
Anomalies such as sags , swells and harmonics are an ongoing threat in electrical circuits — and a common cause of equipment downtime . Power quality meters strategically sample the AC voltage at different points and track slowly changing variations in the electrical waveform . Using this information , operators can root out any issues before they cause lasting damage .
When it comes to electrical matters , the need for rapid detection is clear : transients can appear , cause damage , and disappear in a few millionths of a second . Similarly , a voltage spike typically lasts one to 30 microseconds and can reach over 1,000 volts .
Therefore , acting quickly to install a measurement device is critical , but so is choosing a meter that tells you what you need to know .
What can it measure ? Usually , the dashboard warning lights in your car will tell you if your oil pressure has dropped , if the fuel level is low , or if there ’ s an issue with your steering lock . However , they won ’ t tell you if your cambelt is worn , and
you might not find out something ’ s wrong until it ’ s too late . The point is that you don ’ t know what you don ’ t know — and the new Engineering Recommendation has opened a blind spot by extending the values for measurement .
Visibility of issues across the frequency spectrum is critical , so try to select a power quality meter that captures as many parameters as possible . Usually , low-level power and energy meters will measure things like voltage , current , and maybe power factor but not much else . Even if you purchase a slightly more expensive meter that provides basic harmonic data and frequency values , it ’ s unlikely that this will measure beyond the 50th harmonic , leaving operators back at square one .
Class A meters and analysers can facilitate more advanced troubleshooting of complex electrical systems , and many will measure up to the 100th harmonic . These are the gold standard of power quality meters , and operators will need their accuracy to inform discussions with the distribution network operator ( DNO ).
Fixed or portable ? There ’ s also the matter of duration and how long operators plan to monitor the system . If a circuit board randomly fails or alarms trip , installing portable meters can help engineers perform spot checks by gaining insights at different locations . For example , these meters could detect any changes in low-voltage , medium-power systems , such as spikes in energy consumption . With G5-5 now in place , blind spots in the frequency spectrum are an issue for portable meters because most will only measure up to the 50th harmonic .
Some fixed meters and analysers , like the PQube3 and Janitza ’ s UMG range , can not only measure beyond this point but also facilitate rootcause analysis by mapping long-term trends . Operators can strategically install fixed meters at different locations and record data over several weeks , or even months . For example , with multiple fixed meters in place , a power quality engineer can pinpoint a time when harmonics were detected in the system , and when this caused a spike in energy consumption .
The latest Engineering Recommendations present a challenge for equipment operators because the goalposts for power quality measurement have shifted . However , this also grants an opportunity to improve uptime by detecting a wider range of issues early on .
To help you choose the right power quality measurement and mitigation solution for your application , visit the CP Automation website .
For further information , please visit www . cpaltd . net
54 PECM Issue 68