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Thread: 3 phase generator
10-08-2009, 06:03 AM #1
3 phase generator
I know that this is not exactly the correct forum, but you guys seem to know what you are talking about so here goes. I bought a 10kv military generator that is labeled for both single and 3 phase output. I want to be sure I am hooking up the power leads correctly for single phase 120/240 volt operation. According to the diagram there are four posts for output. L1 is for 3 phase operation only and for the setup I want you are supposed to hook the leads to L2, L3 and L0. Is L0 for the ground or neutral? I am not sure of the correct term? It also has a lug that goes from the frame to a grounding stake. Also if I use it for single phase power will the output be less than for three phase? Thanks for any help.
10-08-2009, 09:22 AM #2
If it is a Y generator, it is 120Y208.
L0 would be the neutral.
Any other voltage from L0 should be 120.
Any line-to-line voltage should be 208.
120/240 could be obtained using a pair of autotransformers.
Your generator is most likely 10 KVA, not 10 kV.
Another possibility is your generator is 120∆240, in which case one side of the ∆ has been center-tapped.
In this case 120/240 would be found between L2 and L3, with the neutral at L0, and three-phase 240 would be found between L1, L2 and L3.
You can simultaneously deliver 120/240 single-phase and 240 three-phase, with any single-phase capacity being taken away from the three-phase capacity.
10-08-2009, 07:42 PM #3
One other thing...
Don- I'll add one little note to what Peter said:
MANY mil-spec generators in the 6-30kva class had diagrams for wiring the generator's output leads for single-phase operation... they used 'double-delta' and 'zig-zag' wiring configurations. If the panel schematics are still visible on your unit, you'll probably see the 120/240 wiring scheme, and you'll see where they have L2 and L3 connected. L0 WILL be a center (or neutral). Chassis ground of the unit SHOULD be same as green-wire ground on your power system. Depending on what your local codes say (and wether or not anyone cares), grounding the generator may or may not be required, and may, or may not be desireable, and may, or may not violate code.
Another thing, unrelated as it may be: Many of these buggers were built to mil-spec using government drawings, with build contracts won by outfits like Hollingsworth and Consolidated Diesel Electric (CONDEC), even ONAN ended up landing a US Govt meal ticket on some... ...and if you look close, you'll see that they're using KATO and Kurtz & Root generator units, engines by Continental (Teledyne), Hercules, Waukesha, etc...
What most likely happened, is that whoever actually WON the contract... subbed the whole darned thing out to the outfit that made the last batch... and just tacked on their 50%... so if your gen looks identical to another guys', and they have different CONTRACTOR names, you know why.