Power Generation: Product Operation and Maintenance

[CatTechnician01]

Community members,

   I have a 12 lead SR4B generator coupled to a G3412C with an EMCP II+. I have been tasked to reconfigure the generator for dedicated single phase 120/240. According to all literature I have for use configuring the generator is possible. My problem is the voltage and current sensing inputs to the EMCPII+ / ATB+. With the deletion of the the third voltage sensing lead and associated current transformer, I believe I'll have a problem with the display reading correct voltage and current inputs. My question is this. Has anyone out there with a similar configuration made this work?

Regards,

Pete  

[mikel]

First question is what are you starting with, a 480 volt 3 phase generator?

Second, to run that as a single phase unit you'll have to signficantly derate the unit, how does that affect the load factor that will be on the engine? These engines do really poorly running for extended times at loads below 45-50%

Third, what AVR do you have?

Yeah you can make it work, final question is are you sure you want to?

Some better info on your part could get you a better answer.

Mike L.

[CatTechnician01]

    Thanks for the response Mike, I had a feeling you would be chiming in sooner or later. To answer your questions I am starting with a 240 volt 3 phase generator. Project Management assures me that the generator was "upsized"  comparably with a G3412 450 kw unit. Our submittal to the customer was 296 kw based on the conversion from natural gas to vapor withdrawal propane. Originally it was rated at 375 kw on natural gas.

    In conversations with the electrical contractor I was informed that there was a "possibility" of close to 1200 amps on this unit with the guest residences, pool house, main residence, caretakers quarters etc.... Please be aware this is a standby unit. Utility on Nantucket is very stable and outages are few and far between. Between the propane de ration and the single phase operation I have not taken the time to crunch the numbers, but I will.

    Thirdly, the generator is equipped with a VR-6B and of course the EMCP II+

With highest regards,

Pete Mandeville 

[mikel]

Your best technical solution may be a transformer, 240 3 phase to 240/120 single phase, this provides full kVA rating from the generator and keeps the AVR and EMCP II+  sensing "standard".

You can connect the generator open leg delta and wire the AVR for single phase sensing, however I have had a few instances where that has been done and someone coming along later wasn't familiar with the connection or sensing wiring, tried to "fix it" and caused some severe problems.

The EMCP II+ connections are a bit trickier, and I don't have a lot of my old info handy, but your best course with that may be to disable the electrical protections in the EMCP II+ and just use a small multifunction electrical protective relay suited for your site installation. Again, down the road someone may come along and not be familiar with how the connections are made to allow single phase operation and protection, and cause problems if they try to make any changes.

Get the nameplate kVA rating from the generator and work out your numbers, not sure I'd use "upsized" as a starting point unless I was sure.  If the unit isn't handy get the serial number and go to TMI and get the generator info.

Hope that helps, Mike L.

[CatTechnician01]

    Mike, I checked thru TMI and this generator arrangement peaks out at 687 kVA. My PM was correct. According to my calculator at 120/240 single phase the de rate would equate to 396 kVA. I'm confident the generator is capable of the the modifications. My problem begins with wiring changes associated with the II+. I have never seen one dedicated to single phase and don't think it is possible. I suggested changing it out to a newer panel ( 3.X or 4.X ) and was questioned about cost.

    Anyway, your expertise and insight is as always appreciated. I will re post with the outcome, stay tuned......

Regards,

Pete 

[mikel]

Pete,

Have you had your TC do a DSN ticket on it?  What do the boys at Griffin say?

I have done it, many years ago on two rental units, unfortunately when I left the dealer I left a lot of that info behind.

I can tell you I promised myself to never do it again for the very reasons I pointed out above, one of the units went into another dealers territory and obviously the renting dealer screwed up (according to the local dealer) so he "fixed it" and did several thousand dollars in damage that we ate.

Your other option would be to remove the EMCP II+ and replace it non-CAT, folks like Murphy, DEIF, DeepSea and Woodward (and may others I'm sure) all have off the shelf options way cheaper than doing EMCP3 or 4 conversion and can likely do exactly what you need. Also with an aftermarket controller it will drive whoever services it in the future to actually look at the prints and documentation (hey at least I can hope).

Good luck, Mike L.