Re: Siemens SED2 VFD / Quincy 10 HP compressor troubles

According to Ignoramus10340 <ignoramus10340@xxxxxxxxxxxxxxxxxxxx>:
On 2007-10-29, Jon Elson <elson@xxxxxxxxx> wrote:


Ignoramus3971 wrote:

[ ... ]

I thought that dropping to 220 under load was kind of normal?


No, it is NOT normal. Now, of course, you are running the VFD on single
phase, and it was not designed for that. So, I would expect a
significant voltage drop, maybe to as low as 300 V or so. That's what
the caps are for. But, 220 VDC is abnormal.


So, it sounds as though I need more caps.

Beware -- more caps with the same rectifier may result in too
much current through the rectifier and thus burn out the rectifier.
Perhaps power up the VFD with the standard caps, then switch in an
additional one, then another, until you have the full set in place.
This will reduce the current surge through the caps -- at least until a
short power outage shuts off the VFD and then the power returns. If
this works, you may want to add a circuit to automatically add the caps
as you start up the VFD. Or -- you can give each additional cap its own
bridge rectifier, so you are not overburdening the built-in rectifier.

Good Luck,
DoN.

--
Email: <dnichols@xxxxxxxxxxx> | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---
.

Relevant Pages

  • Re: 1st post. running 3~ VFD from single phase supply.
    ... Yes, generally you can run a VFD off 1 phase, but with some loss of power ... Your concern is with the rectification and energy storage capacitor ... rectifier on one terminal specifically to handle the increased current, ...
    (rec.crafts.metalworking)
  • Re: questions on power supply for audio amp
    ... > I built a simple unregulated power supply for an audio amp. ... > into electrolytic caps with a resistor+capacitor snubber, ... Millions of audio amps operate with a simple rectifier and filter cap ...
    (sci.electronics.design)
  • Re: Siemens SED2 VFD / Quincy 10 HP compressor troubles
    ... Now, of course, you are running the VFD on single ... it sounds as though I need more caps. ... much current through the rectifier and thus burn out the rectifier. ... short power outage shuts off the VFD and then the power returns. ...
    (rec.crafts.metalworking)
  • Re: Selenium rectifier question
    ... sells 'C-Cap' rectifier replacements and he states that his 5R4 ... wiring into the amp with an Ohm-Meter and try to locate a low ... Next I would check all anode-to-grid caps like eg C19 at V8b. ... overvoltage in the 600V circuit (i.e. reading 900+ when all's supposed ...
    (sci.electronics.repair)
  • Re: Selenium rectifier question
    ... Then the 5R4 ist a directly heated rectifier ... tube and the 5 Volts AC are the heater power. ... To give the amp tubes time to heat up before anode etc power is ... Next I would check all anode-to-grid caps like eg C19 at V8b. ...
    (sci.electronics.repair)