Help on 5th Harmonic Tuned Filter Required

Would love to help Sanjeev but you've lost me. Don't have a clue what you are on about.

Gurudev !

Just need some references & concrete tutorials to design Tuned Filter for 200 KW Machine Load (having THDi & other data as in the original question) powered by 240 KW UPS (Power Source)...As you see only 5th Harmonic is about 26-27%, tuned filter for 250 Hz to counter the existing 250Hz current will serve the purpose.

Hope I could revive your loss of attention..... Just a emotion.. I am actually feeling suffocated for not being able to solve this... my college notes have also been thrown in the dustbin by my dear wife..... please help me all you noble souls... pleeeeeeeeze..

Rgds

Chhotu

PS : If this spoils your weekend mind-share, please ignore the request... luv u all !

You are getting high harmonic current because of - 1. the UPSs are not generating a sine wave, . . or . . 2. the load not being linear.

I would assume that the generated voltage is more trapesoidal - than sinusoidal, . . . resulting in all of the harmonic currents.

You are not getting 3-rd, 9-th, and similar harmonics because of thee-phase operation.

Installing a 5-th harmonic filter - will do more harm than good.

Correct the voltage waveshape.

you need a new drive, your THD should be less that 5% I to conform with 519 IEEE.

I doubt if you will achieve that with the drive you have

I hope that you meant 5% THD V (which they seem to meet). The THD I can easily be in the 10%-15% of the feeder capacity (Total Demand) depending on the installation.

CR4 ADMIN: Deleted Post

Spam: This post was deleted because it contained advertising outside the Commercial Space forum. Please review Section 14 of the CR4 Site FAQ about advertising.

Dear Chhotu,

I agree with view of Mr. olehwi (COMMENT No.2) that 3rd Hormonics and Multiples of 3rd Hormonics are NULLIFIED or ANNULLED on account of STAR WINDING of ALTERNATOR. Therefore 3rd and 9th Hormonics as referred in your Table is TO BE IGNORED.

SINUSOIDAL WAVE FORM for the OUT-PUT SUPPLY is a MUST. Pl. get it checked. Pl. provide a circuit diagram and what is the size of Earting Conductor provided and what is the Earth Resistance.

What does the equipment supplier says.?

I have also phased a similar problem but EARTHING was defective, and after setting right the problem is solved. But personally I feel some thing more is to be done.

However our CR4 members will be in a position to share their knowledge and advise.

Thanks,

RAJESWARI

There are 4 answers to your question:

1,. The UPS and its capacitor was never specified for such an application. Capacitors are specified and limited for such purposes in any switching power supplies.

2,. The harmonics exceed manufacturer's specification.

The next two involves you in design, testing and manufacturing, so be advised.

3,. Properly sized chokes in all legs will cut down on harmonics

4,. A diplexer: high pass / low pass combination. The low pass puts power thru, the high pass terminates harmonics in a resistor.

I would assign 70% to 1,. 25% to 2,. and less than 5% to 3,. and 4,. success.

Any supplementary filter will have some degree on interaction with the UPS. Refer to the UPS manufacturer for the specific.

Do not follow the casual advises of simply installing a tuned capacitor bank. It is much more difficult than this. Have a real pro look into this problem and design a proper passive filter. It must be sized properly and tuned to avoid resonances with the UPS control loops.

From my experience, do not install an active filter on the load either. Its control loop is likely to interact violently with the UPS control loop. Not happy mix.