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Precise automatic positioning control would require a closed loop control that includes encoder, regenerative braking or snubber resistors, vector control for the VFD. A cheap suggestion would be a slow-down sensor changing VFD speed reference, a stopping sensor and a mechanical brake. Reduces...

Maybe these points can be useful: Breaker(load center feeders) ground current sensing:To apply a core balance CT and a ground relay (50GS) set a little bit higher than the current limited by the grounding resistor. This prevents the risks of a second ground fault on other phase at different...

Hi Mr.electricuwe You was MVP solving my doubt about 12 pulses series converters some months ago. Could you please help me again?

Mr.David The motor runs just in one direction but I think you are right. I will try to "draw" it. At left side consider fwd bridge fed by the first delta 2ry.Positive bus at top.Add a reactor and HSCB and create node A. At right side consider the reverse bridge fed by the second delta 2ry...

Sorry. Surely the misunderstanding is caused by my bad english. One 2ry winding feeds the forward bridge. The other 2ry winding feeds the reverse bridge. The question is the gain if compared with conventional arrangement back to back fed by a single 2ry winding.

This discussion about low voltage systems be solid grounded or not comes from the 60's when I was young and my prefered book was "Electric Power Systems" by Donald Beeman. I have experienced 460V system (Brazil's no-load system voltage for industrial aplications)resistance grounded...

Thanks I am really sure that transformer is a delta/delta/delta.This converter is used to drive a shear (left side) that must be electrically synchronized with right side shear. How much to be gained from two six-pulses converters connected from the same source?

Instead of a conventional back to back 6 pulses converter connected to a single secondary winding I found an old circuit where each set of thyristors is connected to a separated delta winding.Reactors were introduced between the DC buses of the two thy groups.I would like to understand the...

Thank you all. Now it is clear for me how the series converters work. Considering all answers, specially from electricuwe,and indicated books it was possible the full understanding, including a diode matrix that remakes the starting triggering condition for the cases where very low current level...

Thanks to spargher, warspeed and skogsgurra My doubt is exactly how they work in SERIES if there is a time delay between corresponding pulses for each converter. As I said to sparguer I am sure they really work and this can be checked typing at www.google.com -12 pulses converters A theory...

Thank you spargher The application for this technology is to drive big DC motors(4000kW).Here in Brazil it is applied, for example, in rolling mills for heavy beams. This configuration , two converters connected in series driving one motor, virtually eliminates 5th and 7th harmonics orders and...

I would like to understand the triggering sequence for two thyristors converters connected in series( double secondary transformer wye/delta). The 30 degrees lag pulses for one thyristor converter is clear for me but I cannot understand how the two converters are triggered at the same time if...

I would like to understand the triggering sequence for two thyristors converters connected in series( double secondary transformer wye/delta). The 30 degrees lag pulses for one thyristor converter is clear for me but I cannot understand how the two converters are triggered at the same time if...