Input Line Reactor

[lukin1977]

hi

can anyone explain me what are input line reactors and when are they used?

Thanks,

lukin1977

 

[DickDV]

Input line reactors are simple choke coils placed in series with each phase. That would be three coils and they are typically wound around a single iron core to make one unit.

They function as high frequency filters blocking high frequency harmonics from the drive going backward into the power network and also blocking high frequency noise in the power network from getting into the drive.

There's lots more detail about these. You should do a search on this forum for good reference material.

 

[lukin1977]

Thanks DickDV

I am doing the search right now

One question: The reactors affect the power factor making it more inductive?

lukin1977

 

[waross]

A different type of input line reactors may be used in large power installations. The purpose is to introduce added impedance so as to limit fault currents. These units are generally air core so as to avoid saturation issues. Under normal currents, the low resistance predominates and they present little inductance.
Under fault conditions the reactance predominates and the current becomes highly reactive. A transformer has similar characteristics, so adding an inductor to a transformer makes little change to phase angles but does lower the available fault current.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[LionelHutz]

The largest gain from using a line reactor is to filter the harmonics. Typically, the current THD of a VFD with a diode bridge front end can be around 130%. A 5% line reactor can lower this to around 30%.

An inductor presents a high impedance to high frequencies. So, a line reactor can help filter high frequency voltage transients from the supply, giving some extra transient protection to the VFD.

 

[Skokian]

A line reactor will reduce line current from around 140% of FLA for a standard six pulse VFD to around 105% of FLa or a 5% reactor or a bit higher for a 3% reactor.

These reactors also serve to protect the storage capacitors from over-voltage due to line spikes and transients. Note that these will be rectified regardless of where they appear on a phase voltage waveform.

More info. is here:

http://mtecorp.com/

http://transcoil.com/display/router.aspx

These are typically three coil units with six leads.

A D.C. link reactor can also help do both jobs (reduce harmonic currents and reduce effects of transients, spikes and surges). The above links also have info on D.c. link reactors. These have two coils; but be careful in sizing wiring conductors since these handle the entire power flowing thru the VFD to the motor.

Hope this helps.

Regards . . .

Jim S. Nasb