Comments on: Harmonics current mitigation of electrical system

By: Carlynda

Carlynda — Wed, 21 Dec 2011 12:39:17 +0000

Deep thought! Thanks for cornitubting.

By: roby moraes

roby moraes — Sat, 10 Sep 2011 09:39:32 +0000

we just finished the mall project & in this peak summer we checked harmonic study & found 04 nos of panel are showing total demand distortion limit is as per below detail
R % TDD = THDI x (I1/IL) =22% x (830/1565.7)=11.7%
Y % TDD = THDIx (I1/IL) =22% x(814/1565.7) =11.4 %
B% TDD = THDI x(I1/IL ) =21%x (853/1565.7 )=11.4%
%total demand distortion (%TDD)
LV MDB Isc /IL 41.5 TDD R11.7% Y 11.4% B 11.4% as per IEEE 519 1992 standards 8% is acceptable limit we need metegation plan how we can close this issue by doing less modifaction in the system & expence wise total 4 nos of MDB,s are same value , the active load in this panels is VFD,s lighting ,motors ,chillers with inbuilt VFD , fan coil units ,air handling units

By: Nathan Lee

Nathan Lee — Thu, 30 Sep 2010 16:46:55 +0000

battery chargers that are made in china are a bit under rated so i don’t use them anymore-:*

By: Ava Davis

Ava Davis — Wed, 11 Aug 2010 16:18:41 +0000

may friend had a china made battery charger and it overheated after a week’”"

By: razia

razia — Thu, 31 Dec 2009 12:06:36 +0000

wow Great………

By: Raed Odeh

Raed Odeh — Tue, 24 Nov 2009 23:34:11 +0000

Hi, glad to explain
Harmonics in layman’s terms : Bacteria or germs that appear under the microscope of a unhealthy blood sample.
Any signal that travels at frequency which is diffrent from the system fundamnetal frequency is a harmonic. In a 50 Hz system a 60Hz current is considred a harmonic. On the contrary, a 50 HZ current is considred a harmonic in 60HZ system.
Voltage harmonics generally increase transfomer’s eddy losses, overload capacitors ” can be RFI caps at the input of VFDs.

while current harmonics increase heat losses as voltage drop across transfomers windings as well resonance in capcitor banks.

the best approach in manging harmonics in a multi VFD installation is to use line reactros , this should probaply fix 60% of the problem then adecision will have to be made to apply a suitable harmonic mitigation technique. From My experience assuming the VFDs donot have line reactors , the reactors should significantly rectify the problem.

By: ehsan

ehsan — Tue, 20 Oct 2009 08:11:02 +0000

respected electrical professional can you please provide me with the circuit diagram on the following topic because its urgent . and this should be carried out using active filter and not passive filter .

Harmonic Mitigation: Filtering harmonic currents from the neutral of three phase systems with single phase non-linear loads
my email address is( ehsanurrub86@hotmail.com)

By: Orlando

Orlando — Sun, 30 Aug 2009 05:17:00 +0000

Dear Electrical Professionals, had understand the destructive effect of Harmonics, as it create unwanted heat enrgy, causes loss of memory of computers, causes disturbance of electronic controllers, causes early rewinding of motors as it destroy winding insulations and foremost as it causes error in Electric Meter readings normally the error increases whaqt the electric meter reads, which is advantageous to Utilities.

What I need to know please, is what are particular effect of Voltage Harmonics and what the Current Harmonics destructively do in a Electrical system?

By: Don Phelan

Don Phelan — Wed, 19 Aug 2009 09:33:50 +0000

Can you explain harmonics in layman’s terms, it’s effects, causes, and remedies?
I’m doing some work at a manufacturing plant that has 20-30 VFD’s from different manufactures and we are having issues with harmonics.
We have changed out some “inferior” drives and improved somewhat, but still have issues.

What effect does current harmonics have? How do they effect the system i.e.
would one bad drive affect the incoming service and/or all equipment/or drives?
Also same question with voltage harmonics.

Thanks,
Don Phelan
MP&E Supt.
John Bouchard & Sons Co.

By: asad jatoi

asad jatoi — Sun, 16 Aug 2009 17:12:05 +0000

Dear Sir,

1st of all I am glad to read all things about Electrical system. and i hope you will provide help to us time to time.
Sir I am a associate Engineer (Hired) in Karachi electric Supply Company I have worked 4 years on Distribution network HT,LT over head & Under ground system now I supervising the Installation of 1PMT
project problem with me that I have DAE in Auto mobiles. & my Expearance is in electrical side company says submit the electrical certificate for become as our employment please help me in this regard. My mail address is asad.ja.toi@hotmail.com if any certification is available online I can pass the examination. sir please any one help me.