Tuesday, December 25, 2007

2-71 Detroit Diesel "Eveready Bunny" generator



I haven't done much to it yet. I added a muffler (still pretty loud), AND I discovered that the voltage was quite high, because it was running at 1800 rpm (90 Hz) instead of 1200! Here it is running at 51 Hz or just over 1000 rpm and 119 volts phase-neutral, into a ~1500 watt load. I probably need to adjust the voltage down to keep it under 130V at 1200 rpm/60 Hz, and let the phase-phase voltage be whatever it is. Anywhere from 208-260 would be fine.
I was happy to find that the overvoltage problem was caused by an overspeed condition; that's easier to fix than a problem in the field control circuit, which is what I initially suspected. 1800 rpm is not enough to hurt the engine; in fact that is a more common running speed for a 2-71 than 1200.
These railroad sets were actually two-speed switchable via a solenoid. They were used on reefer cars; the 1200 rpm position gave rapid cooling and standard 60 cycle electrical power, and they could be switched to 800 rpm for times when demand was lower. This gave 40 cycle power, which simply slowed the 3-phase motors that powered the refrigeration compressors.
I have some ideas for using it in the 40-cycle setting, for reduced noise and fuel consumption.
I plan to run it on waste vegetable oil, at least during the hot summer months.

6 comments:

Anonymous said...

speaking as a master electrician and a generator master-tech, I would strongly recommend running at 1200rpm (60hz for a 6-pole power alternator) and take the time to adjust voltage output at the AVR. Line-to-Neutral voltage should be 115v-125v (120v optimal) and Line-to-Line voltage will be what it is depending on the winding configuration in the alternator, but anything higher than 250v is NOT good for your loads.
Adjust throttle to give approx 61.5-62hz under no-load condition and that will keep you close to 60hz at full load.
A little extra fuel savings isn't worth burning up your appliances and electronics!
Also, you need to run a single wt diesel oil such as delo 100 40wt in this engine. It's a two cycle engine, which has different stresses internally, therefore requiring a lubricant that is made for two cycle engines. The 2-71 is a tank, and can withstand some serious abuse/neglect, but proper care will return many more hours of operation than any modern engine.
Try to fabricate a heat exchanger setup using the cooling system to pre-heat your WVO. This will burn more efficiently, but not help for startup, sorry.
P.S. NEVER NEVER use ether or any other starting fluid on a diesel!!! serious damage will result!!
Good luck, Jason Smyth
myspace nick: Guiltydog

Tracy said...

Thanks for your comments, Jason; you are absolutely correct. However, the loads I am using at the lower frequency are loads that are not very frequency-sensitive, such as stick welders, large power tools, and simple stepdown transformers, rectified to charge a battery bank.
You are correct on the oil, too: it must be a straight 40 weight (50 in extremely hot conditions) meeting CF-2, and less than 1% sulfated ash. I haven't had any luck finding Delo 100 in my area (Delo 400 doesn't meet spec) so I am using Texaco Ursa Extra Duty 40 wt. which does meet the spec. Shell Rotella T 40 wt also meets the spec, but just barely.

Tracy said...

For cold-weather starting, I have on occasion used WD-40. It is kerosene-based and uses propane as a propellant, so it works but is gentler on the engine than ether. I don't really like even doing that, though. I think the ideal solution is a heat gun directed into the intake, powered by the inverter in my truck. Both my truck (Cummins 6BT) and tractor (Buda 6-230) have intake heating grids which do the same thing.

Anonymous said...

ive used starting fluid on my 2-71 for 3 years and run it every day it is cold, it has 56,000+ hours on it and it runs great..... so there goes that theory

Vaughn Hoke said...

There is a procedure for cold starts with ether. I use gasoline on a rag over air cleaner ( hold onto the rag it will get sucked into esd housing.

Vaughn Hoke said...

There is a cold start procedure in the old Detroit manuals using ether. I use gasoline e on a rag over air cleaner ( hold onto the rag it will get sucked into esd housing)