Harmonic filters isolate harmonic current to protect electrical equipment from damage due to harmonic voltage distortion. Harmonic filters mitigate the detrimental effects of harmonic distortion, which can be manifested in many different ways. Examples include increased heating effect on electrical distribution equipment and cables, electronics miss-timings (computers, fax machines, etc.), capacitor overloads, fluorescent light flickering, and others. Filter type and signal type are...
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Q & A on Harmonic Filters

We asked our users for their input on Harmonic Filters. Here are the results of 72 users familiar with Harmonic Filters.

Who Took Our Poll? | Design Trends | Applications and Use | Features | Buying Advice

Who Took Our Poll?Top

Design TrendsTop

Q:
What new technologies are influencing harmonic filter design?
9 answers
Answers:
Active filtering based on IGBT power electronics, fast computing and clever software.
~Stefan M, Head of Strategic Marketing, Luterbach, Switzerland
Zig Zag transformers, K-rated transformers, neutral blocking filters.
~David C, Technical Support, Davenport, OK
Power semiconductors (IGBTs) enabling active filter design.
~Ian M, Design Engineer, Kuala Lumpur, Malaysia
High speed transistors / devices and improved capacitors.
~Steve P, Marketing/Sales, Pittsburgh, PA
Energy quality
~Thomaz C, Engineer, SaoPaulo, Brazil
Microprocessor
~Research & Development, Mexico, Mexico
Clear energy
~Juanjuan Y, Research & Development, Singaproe, Singapore
Schaffner
~Rengasamy Mani, Research & Development, Chennai, India
IGBT's
~Umesh S, Operations, Dubai, UAE

Q:
From your perspective, which companies are creating the most innovative harmonic filters?
10 answers
Answers:
ABB, Schneider, Toshiba
~Umesh S, Operations, Dubai, UAE
Square D and Harmonics Limited
~David C, Technical Support, Davenport, OK
Vectek (New Zealand) marketed through ABB.
~Ian M, Design Engineer, Kuala Lumpur, Malaysia
Mesta Electronics
~Steve P, Marketing/Sales, Pittsburgh, PA
Ablerex, Taiwan
~Lall S, Directir, Auckland, New Zealand
US companies
~General Corporate Mgmt, Tunis, Tunisia
Meruspower
~Thomaz C, Engineer, SaoPaulo, Brazil
Schaffner
~Rengasamy Mani, Research & Development, Chennai, India
Schaffner
~Stefan M, Head of Strategic Marketing, Luterbach, Switzerland
GE
~Juanjuan Y, Research & Development, Singaproe, Singapore

Applications and UseTop

Q:
What are some of the applications you have used a harmonic filter for?
20 answers
Answers:
Large industrial processes, (e.g. hypochlorate plant pumps) Specific applications of harmonic filters for mechanical pumps (e.g. chillers,) Specific applications of harmonic filters for mechanical fans (e.g. AHUs) Specific filters to remedy VFD pump harmonics exceeding IEEE 519 recommendations.
~Engineering, Design, Dulles, VA
A harmonic filter was needed to filter out high frequencies in the 5th harmonic that were in the transmission system connecting a new wind farm to the grid. The source of the harmonics was unknown and the C-type filter was designed to protect the turbines and to mitigate the low order resonance condition.
~Engineering, Design, Cedar Rapids, IA
The harmonic filters typically encountered are used with 3ph AC motor controls - inverters/ VSD / VFD. In these cases, 1 or more inverter(s) on the power system requires Harmonic filtering to comply with or meet the intent of IEEE-519.
~Steve P, Marketing/Sales, Pittsburgh, PA
When specifying variable speed drives on certain applications, we have utilized a harmonic analysis and offered harmonic solutions required for the application.
~Marketing/Sales, Auckland, New Zealand
Motor drives UPS Water/Wastewater treatment plants HVAC Building power Shipboard applications Industrial factories Petrochemical industry
~Stefan M, Head of Strategic Marketing, Luterbach, Switzerland
With booster water pump- 350 HP controlled by VFD (Variable frequency Drive & on 265 KW ESP's
~Umesh S, Operations, Dubai, UAE
Output of sine-wave inverters Input of 6-pulse rectifier circuits
~Ian M, Design Engineer, Kuala Lumpur, Malaysia
To be used in water/waste water, pumping stations, various plants.
~Engineering, Design, Edison, NJ
To reduce the 3rd harmonic which becomes additive in the neutral.
~David C, Technical Support, Davenport, OK
Non -linear loads (PWM) i.e. Variable Frequency Drives
~Engineering, Consulting, Lower Templestowe, Australia
Harmonic mitigation and reduction of voltage notching.
~Lall S, Directir, Auckland, New Zealand
Made a prototype filter for academic purpose.
~Shali S, Engineering Consultant, Windhoek, Namibia
Solid State Single Sideband Transceivers
~Jorge R. Mallo, Electronic Engineer, Buenos Aires, Argentina
Reduce harmonic current
~Juanjuan Y, Research & Development, Singaproe, Singapore
Power factor correction
~Thomaz C, Engineer, SaoPaulo, Brazil
Adjustable speed drive
~Engineering, Other, Spb, Russia
Harmonic mitigation
~General Corporate Mgmt, Tunis, Tunisia
LIFT, Escalator
~Rengasamy Mani, Research & Development, Chennai, India
Lighting design
~Research & Development, Mexico, Mexico
SMPS
~General Corporate Mgmt, Levittown, NY

Q:
Please share with us any “non-standard” applications that a harmonic filter has been used for.
7 answers
Answers:
3-phase phase-controlled electric heater (200kW rating). For this I split phase-controlled heater into two equal stages, controlled them in balanced fashion and fed each stage with supply phase-shifted +/- 15 degrees power supply. For supply used a "differential delta" autotransformer of 50kVA rating. This canceled 5th, 7th and 11th harmonics and proved o be an economic solution.
~Ian M, Design Engineer, Kuala Lumpur, Malaysia
I have used harmonics filters with pump jacks in the oil field.
~David C, Technical Support, Davenport, OK
Fast DC chargers for electric vehicle charging stations.
~Stefan M, Head of Strategic Marketing, Luterbach, Switzerland
Balancing an out of balance 3 phase line.
~Steve P, Marketing/Sales, Pittsburgh, PA
Elevator, All Commercial Building user.
~Rengasamy Mani, Research & Development, Chennai, India
Power factor correction
~Thomaz C, Engineer, SaoPaulo, Brazil
SSB, use the Tx harmonic filter to improve the receiver image reyection
~Jorge R. Mallo, Electronic Engineer, Buenos Aires, Argentina

Q:
Do you know of any disastrous mistakes that occurred due to the incorrect usage of a harmonic filter?
4 answers
Answers:
A customer didn't plan for plant expansion, so harmonic filtering wasn't adequate when the plant was finished - every time certain motors were started, the plant tripped off line due to excessive harmonics.
~Steve P, Marketing/Sales, Pittsburgh, PA
Spurious Tripping of plant equipment due to harmonic pick up, Dirty power to system due to harmonics. Caused telecom equipment to malfunction.
~Umesh S, Operations, Dubai, UAE
Burn outs due to bad lay out for high power harmonic filters.
~Jorge R. Mallo, Electronic Engineer, Buenos Aires, Argentina
Incorrect use of CTs
~Lall S, Directir, Auckland, New Zealand

FeaturesTop

Q:
What would your design or feature "wish list" be for this product?
11 answers
Answers:
Active filter that is integrated into the inverter with an option to be a separate stand alone device. Harmonic filtering quality as a selectable feature...IEEE-519, less than IEEE-519 and better than IEEE-519. Scalable. Monitoring and metering capabilities - it should be able to provide a harmonic analysis prior to being "on" and a harmonic analysis after it is "on" - the before and after data. Tunable.
~Steve P, Marketing/Sales, Pittsburgh, PA
Reduced cost Improved supplier knowledge of the product they are selling Easier means to size the filter required (e.g. computer software)
~Ian M, Design Engineer, Kuala Lumpur, Malaysia
More compact magnetic components. Passive filters without capacitors.
~Stefan M, Head of Strategic Marketing, Luterbach, Switzerland
To come up with an industrial self tuned (automatic) filter
~Shali S, Engineering Consultant, Windhoek, Namibia
To reduce harmonic distortion to comply with IEEE519
~David C, Technical Support, Davenport, OK
Decreased footprints with reliable protection schemes.
~Engineering, Design, Cedar Rapids, IA
Disturbance free power to user.
~Rengasamy Mani, Research & Development, Chennai, India
With 5% THD filters, still creating problems on old telecom equipment at offshore.
~Umesh S, Operations, Dubai, UAE
Compact filter for low voltage
~Thomaz C, Engineer, SaoPaulo, Brazil
Harmonic attenuation.
~Jorge R. Mallo, Electronic Engineer, Buenos Aires, Argentina
Low in cost
~Juanjuan Y, Research & Development, Singaproe, Singapore

Q:
Is there any advice you want to share with users to help them avoid common errors in selection or usage of a harmonic filter?
6 answers
Answers:
If you are supplying harmonic filter to correct harmonic problems generated by other equipment supplied by yourself (e.g. rectifier, VFD, electric heater) then be sure that you are not correcting everyone else's problems! Otherwise you may overload your filter.
~Ian M, Design Engineer, Kuala Lumpur, Malaysia
Pay special attention to installing the CTs of active filters the correct way 'round. This is one of the most common mistakes during AHF commissioning.
~Stefan M, Head of Strategic Marketing, Luterbach, Switzerland
If the total harmonic distortion isn't very high, you can use a line reactor "inductor" to reduce harmonics. They are relatively inexpensive.
~David C, Technical Support, Davenport, OK
Spend time understanding and investigating how to properly size the device - and follow the vendor guidelines.
~Steve P, Marketing/Sales, Pittsburgh, PA
Proper sizing & other equipment in the vicinity of VFD's.
~Umesh S, Operations, Dubai, UAE
Be careful about input impedance.
~Jorge R. Mallo, Electronic Engineer, Buenos Aires, Argentina

Buying AdviceTop

Q:
Do you have any advice for people relative to buying or using a harmonic filter?
5 answers
Answers:
Harmonic analysis is a difficult process, because full knowledge of supply impedance (reactive and resistive) is needed to enable estimation of voltage harmonics at the point of common coupling, as well as accurate estimates of harmonic currents generated by the load.
~Ian M, Design Engineer, Kuala Lumpur, Malaysia
Use a power quality analyzer before and after studies to make sure the filter is working.
~David C, Technical Support, Davenport, OK
Make sure to have a competent partner to give advice for proper selection, installation and commissioning.
~Stefan M, Head of Strategic Marketing, Luterbach, Switzerland
Plan for the future - understand if you are planning for expansion get a device that can handle the expansion.
~Steve P, Marketing/Sales, Pittsburgh, PA
Study carefully the selection & laying of cables & grounding of the system.
~Umesh S, Operations, Dubai, UAE

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