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Line Harmonics Filter (LHF) draws power at no load also

Created by: PSANTOSHV at: 11/21/2014 7:42 PM (4 Replies)

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11/21/2014 7:42 PM	Rate (0)
PSANTOSHV Member Joined: 9/20/2010 Last visit: 11/11/2021 Posts: 6 Rating: (0)	Dear Expert, We have installed 900 kW MV 690 drive (560 kW x 2 modules) along with Line Harmonic Filter. There was some recomendation by client to accomplish LHF. But we got very surprised that enery meter (multi function meter) installed in MV breaker shows heavy current draw while drive/motor not even running. This drawn current varies from 240 amperes to 250 amperes while in load run time total current could be 600 to 940 ampere depend on load. (Motor full load is 940 ampere). we have checked current from clamp meter & it really shows same. How we can avoid this huge loss for nothing.Is it drive configuration mistake or what, I am attaching SLD also. LHF type : 6SL3000-0JH35-8AA0 SINAMICS G130 Drive Converter Chassis Unit : 6SL3310-1TH35-8AB3 Please help. Thanks. Regards Santosh Verma Attachment SLD of 541MD1_900 kW.pdf (174 Downloads)

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11/22/2014 3:47 PM	Rate (0)
Sinex1 Regular Member Joined: 4/20/2009 Last visit: 9/27/2023 Posts: 20 Rating: (4)	Hello Santosh, It isnormal that you measure this current on a LHF. But it's a pure reactive current (capacitive). When you have a 50hz power supply, this no-load current could be about 25% of the nominal LHF-current. When you are in 60Hz area, you have about 20% no-load current. It's perfectly normal. Sinex

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11/25/2014 5:25 PM	Rate (0)
PSANTOSHV Member Joined: 9/20/2010 Last visit: 11/11/2021 Posts: 6 Rating: (0)	Dear Mr. Sinex, Thanks for reply. I am now sure that this is capacitive current, but I have 2 points. - Whether this reactive current (by LHF) may effect on Load consumption i.e. drawn energy motor Killowatt hour. If we measure at Breaker MV side, then consumption average kWh is 60-70 % while drive draws current 85-95 %. - Client has to pay to electricity board for this reactive current? i.e. may be electricity borad consumption meter also measures the reactive load as consumption. Thanks in advance Santosh

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11/25/2014 10:19 PM	Rate (0)
Sinex1 Regular Member Joined: 4/20/2009 Last visit: 9/27/2023 Posts: 20 Rating: (4)	Hello, You will not pay for the purereactive current. Of course, the measurement of the current a customer needs to pay, is the summation of all total currents. The result from the filter is that you loose about 1% of efficiency of your converter (inclusive filter). It will go from 98% to 97% efficiency. Furtheron, the filter will decrease 5th, 7th, 11th and 13th harmonics, just like you should have a 12-pulse system. Sinex

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11/30/2014 6:56 PM	Rate (0)
PSANTOSHV Member Joined: 9/20/2010 Last visit: 11/11/2021 Posts: 6 Rating: (0)	Sinex1 Hello, You will not pay for the purereactive current. Of course, the measurement of the current a customer needs to pay, is the summation of all total currents. The result from the filter is that you loose about 1% of efficiency of your converter (inclusive filter). It will go from 98% to 97% efficiency. Furtheron, the filter will decrease 5th, 7th, 11th and 13th harmonics, just like you should have a 12-pulse system. Sinex Hello Sinex, Thanks again I still want to know how much power factor / energy consumption can improve as I stated earlier.. "Whether this reactive current (by LHF) may effect on Load consumption i.e. drawn energy motor Killowatt hour. If we measure at Breaker MV side, then consumption average kWh is 60-70 % while drive draws current 85-95 %." Is something wrong in our measurement...please. BR Santosh

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