PMG retrofit to Stamford alternator
PMG retrofit to Stamford alternator
(OP)
One of many things I'm responsible at work for is a 500kVA diesel genset which I inherited via my predecessor. It isn't a particularly well-specified machine for the job it is doing - standby duty - but I'm toying with retrofitting a PMG in lieu of the bus-fed excitation to improve its fault-clearing capability. The alternator has a cover which, when removed, would allow access to the outboard end of the shaft which I believe is machined to accept an adaptor or coupling to a PMG.
Brief inquiries have drawn a blank in terms of OEM parts for this machine, and because it wasn't originally supplied with a PMG Stamford aren't being overly helpful in converting it. I understand why, it's just a little frustrating too. I can probably obtain a PMG for a similar set and have an adaptor ring manufactured if needed. Has anyone done anything similar in the past?
Brief inquiries have drawn a blank in terms of OEM parts for this machine, and because it wasn't originally supplied with a PMG Stamford aren't being overly helpful in converting it. I understand why, it's just a little frustrating too. I can probably obtain a PMG for a similar set and have an adaptor ring manufactured if needed. Has anyone done anything similar in the past?





RE: PMG retrofit to Stamford alternator
The PMG was small, say 6-inch diameter and 6-inch long. This for a 30MVA generator. Later we developed an integral pmg system, I think.
Newton Derby are still there, and part of winder. their website says they can do excitation solutions, so give them a try http://www.winderpower.co.uk/product/rotating-mach...
RE: PMG retrofit to Stamford alternator
RE: PMG retrofit to Stamford alternator
We already deal with Winder Power on the transformer side of the business, I will inquire whether they can help us.
Genhead - will have to find out, not at work right now.
RE: PMG retrofit to Stamford alternator
Here is a link to their customer service, service-engineers@cumminsgeneratortechnologies.com
I think this is still the factory authorized Avk/Stamford house in the UK, r.taylor@baumuller.co.uk or mail@baumuller.co.uk
I've used these guys in the US to get parts for most of the smaller (less than 1MW) units I run across, http://www.dieselgeneratorsmiami.com
If you do retrofit a PMG I would suggest you consider adding set of fuses or a breaker on the PMG output, Stamford does not protect the output of their PMG's and I find in many cases a failed AVR also results in a toasted PMG. I had an interesting discussion with a Stamford engineer on the subject at PowerGen last year. Maybe they just like selling the parts. I do it pretty much anytime I replace an AVR or PMG.
Hope that helps, MikeL
RE: PMG retrofit to Stamford alternator
RE: PMG retrofit to Stamford alternator
Second that.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: PMG retrofit to Stamford alternator
RE: PMG retrofit to Stamford alternator
The engineering world awaits!!
RE: PMG retrofit to Stamford alternator
I promise I will update this thread when I have something to add!
RE: PMG retrofit to Stamford alternator
Did you consider a excitation booster system? The module is power from the battery.Below is a link for one type.
http://www.kutai.com.tw/download/epmg1270epmg2470/...
RE: PMG retrofit to Stamford alternator
No, I hadn't seen those before. Thanks.
I've already converted
this machinea sister machine with a steam turbine prime mover from being dependent upon residual magnetism for build-up to one with active field flashing from a battery source, so most of the infrastructure is in place to incorporate one of those devices. A few years ago I'd never heard of Kutai until I fitted one of their AVRs to my little B&S standby set at home, and that choice was largely down to them being cheap. What is the general opinion on quality and reliability? The last thing I need is an emergency set failing on demand!Edit: see crossed out bit.
RE: PMG retrofit to Stamford alternator
https://www.basler.com/Product/CBS-212A-Current-Bo....
RE: PMG retrofit to Stamford alternator
http://www.hipowersystems.com/Online-store/alterna...
However I think these are only used for their smaller units, up to about 50kVA I think.
I have only a small amount of experience with the Kutai products, all I can say is they are "ok", had to deal with one of their excitation boost modules (different Model) that I was not impressed with, we ended up retrofitting that unit to a PMG. This was several years ago so maybe they have improved, not sure. Need to make sure you have enough output power if you do use it, I think most Stanford tail ends today in that size range are about 4 amps nominal FL excitation current, but some of their older units had excitation systems that had higher field current requirements.
From my own experience with units in this size range, for AVR power overall I find best long term success with a PMG, they are simple, robust and reasonably resistant to problems. Auxiliary winding can also be good, but no real good way to field retrofit them. Over the years have dealt with a number of series boost modules (or Current Boost or Excitation boost if you prefer), mainly Basler and Caterpillar. They work fine but finding someone who understands and can fix them is getting more rare. Personally the idea of a smaller battery powered device wouldn't be my ideal solution, especially one sourced different form the AVR and/or generator manufacturer, but a lot of factors get involved in making that kind of decision.
Field retrofitting a PMG for many years was a Stamford selling point, again, not sure which tail end you have but I'd bet it's likely a pretty good option, just need to find someone willing to do the legwork to get you the right part. But looking back thru some old notes, I can only find a couple of different PMG part numbers, and their excitation system designs in recent years all seem to use the same field voltage and current levels.
Hope that helps, MikeL.