3306 Engine, 3 Phase Generator Conversion

Question #1
I read a thread from 2012 stating that the 3306 is a very reliable engine.
Is the general consensus here still that the 3306 is a very good engine?
The one I'm looking at was built in the 1990s. It still SEEMS to be good.

Question #2
Can an old CAT gen-set configured for 120/208 3 phase be converted to 120/240 1 phase, i.e. 120-0-120 with 120 volts on each side of neutral that can be bonded to ground?

Any help would be appreciated.
Thanks,
JGC

ya with a converter at the price of a whole generator, very pricey!

Yes I believe that the 3306 is a very good engine.

On question two, yes the 120/208 generator can be wired for 120/240 if all of the winding leads are brought out. But you only get 2/3rds of the power output.
So a 30 kva gen becomes a 20 kva gen.

Draw a triangle with the point at the top. mark the left side A the right B and the bottom C Now split the connection at the top and bottom of A
Move B & C down together and connect the top of B to the bottom of A.

Now the top of A is 120 the A-B connection is neutral and the bottom of C is your other 120!

Hope this helps

[quote="BobPV15"]Yes I believe that the 3306 is a very good engine.

On question two, yes the 120/208 generator can be wired for 120/240 if all of the winding leads are brought out. But you only get 2/3rds of the power output.
So a 30 kva gen becomes a 20 kva gen.

Draw a triangle with the point at the top. mark the left side A the right B and the bottom C Now split the connection at the top and bottom of A
Move B & C down together and connect the top of B to the bottom of A.

Now the top of A is 120 the A-B connection is neutral and the bottom of C is your other 120!

Hope this helps[/quote]

REPLY:
Yes - this is very helpful.

If I get the model and serial number of the alternator, is there a place I can look to see if "the winding leads are brought out"?
I'm guessing that to connect as you suggested, I would need 6 leads available - two for each of the 3 phases - yes???

Usually there is a mounting plate for the connections, under that are the wires. Yes there will be at least 6 for the three phases and a couple of small ones that go to the voltage regulator. If it is a dual voltage generator there could be 12. There each phase is split in two and can be wired in series for high voltage or parallel for low voltage. When you get the generator model Google it and see what comes up. If you have a motor rewind shop near you they would know what to do.

To reconnect for 120/240, you have to have 9 leads or 12 leads.

A 6 lead generator would be an odd thing to see, but if you were to reconnect a 120/208 3 phase 6 lead generator into a dogleg as described already, you would get approximately 208/416 single phase instead of 120/240.

There are two options for 12 lead generator ends. Dogleg (sometimes called zigzag .....mistake in my opinion) and double delta. Either one works just fine. The dogleg connection can be obtained from the 120/208 3 phase Y connection without even knowing what the lead numbers are, so that might be one reason to use it over the double delta, but the two are completely functionally equivalent.

CAT used to make mostly 9/10 lead dual voltage 3 phase Y generators. These are reconnectable by either paralleling the windings in 3 pairs for low voltage 208-240 or connecting them in 3 series circuits for high voltage 416-480 volts. In either case the windings remain in a Y configuration because the 10, 11 and 12 leads are permanently connected inside the stator and a single lead brought out for the neutral. A motor shop can cut into one of these 9/10 lead generators windings, split the Y and attach the 10,11,12 leads required for single phase reconnections. BUT this is no guarantee the exciter and regulator will function after the reconnections. Might have to go with aftermarket components to get that to go.

There is a single phase reconnection of the 9/10 lead Y type generators that is properly called the zigzag connection. Unfortunately it requires a rather rare 110-120/220-240 dual voltage 9 lead vs the more common 208-240/416-480 dual voltage 9 lead generator. Using the zigzag on the 208/416 generator produces 208/416 single phase.....not very useful!

With any of the single phase reconnections, the generator end can only produce 2/3 of the former 3 phase kVA rating UNLESS it was ordered as an extended stack option which has a larger than standard winding. This option typically allows single phase load equal to 3 phase kW rating