Canadian Electrical Industry News Week

 

May 7, 2018

HarmonicsBy Owen Hurst

With a focus this month of power quality, test and measurement, it seems prudent to take a minute to return to the basics for understanding harmonic distortion, particularly as the use of items with non-linear loads continues to increase.

Harmonics have been around since the first AC generator was turned on over 100 years ago. However, harmonics were initially not an issue as they very minor over linear loads. It wasn’t until the 1960s that the impact of harmonic distortion became apparent. This is confirmed by V.J. Gosbell, an associate professor at the University of Wollongong who said, “Harmonic distortion is not generally due to the operation of the power system, and was largely absent before the 1960s. At about this time, a different type of customer load with electronic power supplies became popular.”[1] These new products, such as computers and household appliances with electronic controls, had a non-linear load, and if we consider how many items we now use with electronic control it is easy to see how harmonic distortion has become a major issue.

Variable frequency drives (VFDs) also cause a non-linear load that can create harmonic distortion for manufacturing and industrial applications as well.

Harmonics Chart 1

 

 

 


 

 

But first, let’s just step back and take a brief look at what exactly harmonic distortion is.

The easiest way to understand harmonic distortion is to consider the differences in linear and non-linear loads. If we have a standard AC source and a load draw that is linear the draw current will be sinusoidal in nature and for the most part does not disrupt the waveform (See fig.1). For ideal operation the draw does not create a distorted waveform but as mentioned is sinusoidal.
Harmonics Chart 2Harmonics Chart 3












However, if the load draw is non-linear (such as with electronic controls) the waveform is distorted and no longer sinusoidal even though it is drawing from a sinusoidal source (See fig.2). In reality the complexity of the fundamental wave is not important, it is just an element of multiple waveforms that are called harmonics.

Harmonics therefore have frequencies that are integer multiples of the waveform’s frequency. To provide an example on a “60Hz fundamental waveform, the 2nd, 3rd, 4th, and 5th harmonic components will be at 120Hz, 180Hz, 240Hz, and 300Hz respectively.

Thus, harmonic distortion is the degree to which a waveform deviates from its pure sinusoidal values as a result of the summation of all these harmonic elements.”

Important to note here is that harmonics should not be confused with spikes, dips, impulses, oscillations or other forms of transients.

Now that we have identified what harmonics are we can consider how they are measured, which inevitably is the determining factor for identifying if harmonic distortion is causing negative effects on the system. To do this it is necessary to measure total harmonic distortion (THD). THD “is the summation of all harmonic components of the voltage or current waveform compared against the fundamental component of the voltage or current wave.”[5] This can be calculated using a standard mathematical equation, or more often is determined using test and measurement devices that perform the calculations for you. Either way, the higher the percentage the more harmonic distortion on the signal.

Although there are no enforced standards for harmonic distortion they have received a good deal of attention and many utilities have their own regulations which tend to follow the “IEEE Recommended Practices and Requirements for Harmonic Control in Electric Power Systems” (IEEE std. 519-1992).

Standard 519 by the IEEE notes that “computers and allied equipment, such as programmable logic controllers, frequently require ac sources that have no more than 5% harmonic voltage distortion factor, with the largest single harmonic being no more than 3% of the fundamental voltage. Higher levels of harmonics result in erratic, sometimes subtle, malfunctions of the equipment that can, in some cases, have profound consequences.”

Although the standard is voluntary, it is an extremely valuable guideline that has been adopted by many utility companies across the country. With overall harmonic distortion lower than 5%, and no one harmonic registering higher than 3% equipment damage or malfunction is unlikely.

Harmonics Chart 4









However, if harmonic distortion is higher there is the potential for costly equipment damage and potentially dangerous situations for employees. “High levels of harmonic distortion can cause such effects as increased transformer, capacitor, motor or generator heating, misoperation of electronic equipment, incorrect readings on meters, misoperation of protective relays and interference with telephone circuits.”

Harmonic distortion can substantially limit the life cycle of equipment and potentially lead to outright system failure, resulting in additional costs for equipment replacement and loss of revenue due to potential shutdowns. Further, in rare cases, the heat generated in motors and drives has the potential to cause fires, which is obviously a safety hazard.

So, it is critically important to ensure that measurements of harmonics are undertaken and that any harmonic distortion that presents potential issues are addressed. There are several ways to mitigate harmonic distortion, the most common being the installation of a harmonic filter which shunts or absorbs specific harmonics from the power supply. Another potential resolution is a Pulse Width Modulated (PWM) rectifier which can eliminate a number of harmonics to gain acceptable levels.

Harmonic distortion is not going to go away, and we continue to increase our use of items with non-linear load draws increasing issues with harmonic distortion that will inevitably require more direct attention from regulatory bodies.

Owen Hurst is Managing Editor of EIN’s sister publication, Panel Builder & Systems Integrator: http://panelbuildersystemsintegrator.ca


Notes
1. V.J. Gosbell. “Harmonic Distortion in the Electrical Supply System,” PQC TECH Note 3 (Power Quality Centre), 2000, p. 2
2. Total Harmonic Distortion and Effects in Electrical Power Systems, Associated Power Systems, https://www.aptsources.com/wp-content/uploads/pdfs/Total-Harmonic-Distortion-and-Effects-in-Electrical-Power-Systems.pdf
3. Total Harmonic Distortion and Effects in Electrical Power Systems
4. Power System Harmonics: A Reference Guide to Causes, Effects and Corrective Measures, Allen-Bradley, April 2001, p. 1
5. Total harmonic Distortion and Effects in Electrical Power Systems
6. Power System Harmonics, p. 3

Sources
Power System Harmonics: A Reference Guide to Causes, Effects and Corrective Measures, Allen-Bradley, April 2001, pp. 1-7
Alex baitch, M.H. Bollen and V.J. Gosbell, “The Reporting of Distribution Power Quality Surveys” CIGRE/IEEE PES International Symposium on Quality and Security of Electrical Power Delivery Systems, October 2003, pp. 48-53
Total Harmonic Distortion and Effects in Electrical Power Systems, Associated Power Systems, https://www.aptsources.com/wp-content/uploads/pdfs/Total-Harmonic-Distortion-and-Effects-in-Electrical-Power-Systems.pdf
V.J. Gosbell. “Harmonic Distortion in the Electrical Supply System,” PQC TECH Note 3 (Power Quality Centre), 2000, pp. 2-10

Images Source: http://automationwiki.com/index.php/Total_Harmonic_Distortion

 

Changing Scene

  • Prev
In his new role as Stelpro's Vice-President, Sales and Business Development, ...
The Support Equity and Under-Represented Groups project will address the under-representation of ...
Show your support by sharing a photo or experience of how a lineworker has made an impact in your ...
Eleven highly accomplished Hamiltonians are being honoured by Mohawk College as Distinguished ...
Canada’s Minister of Natural Resources recently announced the Governor in Council has ...
ABB recently won an order of eBus charging solutions to support TTC as it modernizes its service ...
A consortium of Canadian energy organizations has been shortlisted to develop the electricity ...
Skills Ontario Summer Camp is a week-long day program for kids entering Grades 7-9.   ...
  Glen Dimplex Americas is proud to announce that its Vancouver facility was recently ...
May 13 to 19 is Powerline Safety Week in Ontario, which is meant to inform people across the ...

Electrician Forum Brought to you by Schneider Electric

As industry experts you know the products you use everyday better than anyone and should have input on what information you receive about products and what could improve them.

Therefore, we want your insight on the biggest challenges or issues you face when installing loadcentres, breakers (CAFI, GFI's…) and other surge protection devices. We ask that you do not provide product specific details but rather your general issues and concerns or any questions that have come to mind while working with these product types. Provide us with your valued expert insight into the issues you have faced so manufacturers can better inform you about the installation and use of these products. Lets generate some discussion that will help guide the Industry.

Make your comments  HERE

 

ABB TXploreOn May 30, 2019, ABB was honoured with an Electrical Review Excellence award for its ABB Ability inspection for transformers – TXplore -- in the ‘Power Product of the Year’ category. Electrical Review is the leading electrical industry publication in the UK.

The judging panel, under the leadership of the highly-respected industry figure – Prof. Ian F. Bitterlin, Consulting Engineer and Visiting Professor at University of Leeds, was impressed by the capability of TXplore to make transformer inspection a much safer activity while also boosting asset availability for power grid operators.

 

Read More

 

 

 

Codes and Regulations Brought to You by the CSA Group

  • Prev
The Code is a comprehensive document. Sometimes it can seem quite daunting to quickly find the ...
The Code is a comprehensive document. Sometimes it can seem quite daunting to quickly find the ...
In this article: Tables — Part B. This section of the Code contains 99 tables of essential ...
In this article: Section 58 — Passenger Ropeways and Similar Equipment. Rule 58-000 ...
  Unauthorized CSA Group certification marks have been found on wiring by Triumph Cable ...
In this article: Section 52 — Diagnostic imaging installations. The CE code is a ...
In this article: Section 46 — Emergency Power Supply, Unit Equipment, Exit Signs, and ...
  In this article: Section 44 — Theatre Installations. The CE Code is a ...
CSA has published C22.2 No. 60947-7-3, the harmonized standard for low-voltage switchgear and ...
  Electric welders. The CE Code is a comprehensive document. Sometimes it can seem ...

 

Lighting ProjectLocated at one of the busiest retail intersections in Montreal’s downtown core, 1411 Crescent is a beautiful art deco structure built in 1934. Four floors of offices sit above retail space on the northeast corner of Ste-Catherine Street. BTB Real Estate Investment Trust purchased the building in 2018 and with its own team growing, chose to move its company headquarters to the new space. They appreciated the charm of the building, and its ideal location in the Golden Square Mile.

To signify this important move, BTB REIT sought to enhance the building’s façade to make it more impactful on this vital city block.

 

Read More 

 

ABBTechFor decades, ABB has made intricate scientific instruments that measure and analyze gases in the atmosphere to help scientists better understand its composition and evolution. Now, ABB is helping to more accurately measure greenhouse gases (GHGs), which are trapping heat in the atmosphere, resulting in an increase in global surface temperature.

One such instrument is an ABB interferometer carried aboard the Greenhouse Gases Observing Satellite-2 (GOSAT-2), which was launched in October 2018 as part of a Japanese government project. 

Read More

 

 

Tools for the Trade

  • Prev
  IDEAL Industries has introduced Combination Drill Taps to its tool lineup. Combining the ...
  Stripping and crimping device, 100 - 240 V input voltage, for insulated ferrules with a ...
Professional all-in-one cutter/stripper for coaxial and twisted pair cables     ...
  Klein Tools' Coax Explorrer 2 tests coaxial cable and maps up to 4 locations   ...
  Ideal Industries' T-14 wire stripper s are ideal for all professionals working within the ...
  The ATS850 conveyor eliminates all types of electro static discharge requirements. ...
  Lorik Tool & Automation has the experience and ability to manufacture a variety of ...
  Ideal Industries' 26 piece insulated Journeyman kit is ideal for new electricians or for ...
  Klein Tools Deluxe Fish Rod Set comes in 19 pieces that when assembled can fish wire and ...
  BendWorks Software was designed to help electrical contractors adopt this new process ...

Product News

  • Prev
Single Phase Power Solutions introduces the 30 HP Belle Single-Phase Motor™ which uses ...
Emerson expands the innovative Greenlee Shear 30T with seven new die sets and a new bare kit ...
ASCO Power Technologies offers its Model 420 surge protective device for point-of -use ...
The new VALVETRAB MS Type 1+2 combined lightning current and surge arresters have a 3+V circuit. ...
A truly smart home does more than just connect you; it works for you. With iDevices' advanced smart ...
Previously available from one of the world’s largest line pulling companies, the PLCS is now ...
Fluke has revamped its entire line of industrial thermal cameras with more premium features packed ...
Emerson has improved AMS Machinery Manager predictive maintenance and analysis software ...
AEMC’s ten New Simple Logger® Data Loggers are small one channel recording devices ...
ASCO Power Technologies, a provider of critical power solutions, releases the third generation of ...

 

Banner VE Smart CameraFeatures included in the latest version of Vision Manager software simplify the integration of VE Series smart cameras into vision guided robotic (VGR) systems and make it easy to correct distortions caused by camera perspective. Also new to the software is the ability to view application images remotely via a built-in webserver. Vision Manager version 1.7.0 is available now for free download.

EASY INTEGRATION WITH VISION GUIDED ROBOTS

All the logic required to integrate a VE Series smart camera into a VGR system is in the software. 

Read More

 

 

Peers & Profiles

  • Prev
Bill Maki is an Electrical Engineer from Thunder Bay, Ontario working as a Control Systems ...
Benedict Electrical Contracting Limited is a locally owned and operated family business in Owen ...
Spark Power Corp. is one of North America’s leading independent providers of integrated ...
Marcia Ranger is a master construction and maintenance electrician, as well as a college professor ...
Con’s Electric Company Limited was established in 1985. Based in Timmins Ontario, only 700 ...
Mark Unsworth is an electrical engineer with over 35 years of experience in project management, ...
Manygo Ho is an electrical designer with AECOM’s Buildings and Places group. Manygo designs ...
Don Neigel is Manager of the CSA-certified panel shop at Delta, BC’s Optimil Machinery. ...
New Brunswick Power recently struck a deal with Joi Scientific to develop an innovative technology ...
The Shock Doctors is an electrical contracting company operating out of Orillia, Barrie and ...

Copper $US Dollar price per pound

Kerrwil Publications

538 Elizabeth Street, Midland,Ontario, Canada L4R2A3 +1 705 527 7666
©2019 All rights reserved

Use of this Site constitutes acceptance of our Privacy Policy (effective 1.1.2016)
The material on this site may not be reproduced, distributed, transmitted, cached or otherwise used, except with the prior written permission of Kerrwil