Drive Output Filter/Choke 5

[GaDawg]

Is anyone aware of an output filter/choke capable of limiting dV/dt to 500V/microsec.? I have a submersible motor application with a maximum of 200ft. wire run between the drive and the motor. This is a 460VAC/3ph./60Hz. application operating a 75Hp motor. The filters I’ve reviewed thus far are capable of limiting dV/dt to 700-800V/microsec. Any suggestions will be greatly appreciated. Thanks.

 

[sreid]

I can't tell you where to find what you want but I can tell you the (mosy likely) reason filters with a lower dv/dt are not available. VFD output filters are primarilly to suppress EMI. Most of the noise comes from some really impressive current spikes that travel dowm the motor leads every time the drive switches. The spikes are surpressed by the series inductors. The voltage rise time is increased via shunt capacitors but these must have damping resistors in series to damp ringing. The bigger the capacitors, the slower the rise time but the damping resistors must dissipate all the energy going into the capacitors. To keep the resistors to a reasonable wattage, the capacitors are usually smaller than one might like them to be.

Is ther a particular reason you need to keep the dv/dt under 700 v/us?

 

[jbartos]

Suggestion: Have you reviewed:

http://www.transcoil.com

 

[GaDawg]

sreid:
The motor manufacturer specifies that the dV/dt must be 500V/usec or less. NEMA MG1 Part 31 does not address submersible motors but the manufacturer has placed this stipulation on their equipment due to design. Line inductors at the motor are obviously not a solution since this is a submersible motor application. Thanks for the information.
jbartos:
Thanks for the suggestion. I've actually been working with them trying to resolve this issue. We usually purchase all of our filter or reactor components from them.

 

[dhammell]

GaDawg,
Sorry for the commercial response, and it may be too late to help, but Princeton Power has recently developed a 75hp 480VAC VSD that generates dV/dt of five (5) V/us, without using any inductive filtering. It is based on a technique called AC-link, which operates differently from PWM. Check out:

http://www.princetonpower.com

 

[DickDV]

I believe that you may need a sine-filter rather than a reactor to meet this spec. Most of the companies that make reactors also make sine-filters. MTE in Milwaukee is one that does. I think TCI does also.