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Could you expand on how an imbalanced load affects fuel efficiency?Unbalanced will just reduce your fuel efficiency due to the unbalanced current going to neutral. Other than that no, it wont harm it.
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Could you expand on how an imbalanced load affects fuel efficiency?Unbalanced will just reduce your fuel efficiency due to the unbalanced current going to neutral. Other than that no, it wont harm it.
As a generator is loaded the engine has to work harder to fight the magnetic flux. If you load 1 leg (or 2 legs) the engine is working harder to keep up. Now the unbalanced part, the unbalanced current returns to the source (generator head) via the neutral (its being wasted and not performing any useful work).Could you expand on how an imbalanced load affects fuel efficiency?
Because its energy returning to the head. In a balanced environment the neutral is carrying 0 amps each leg acts as the return for the other (essentially these are now 2 120 volt devices wired in series) all energy created is being turned into useful work. When there is an imbalance the current carried by the neutral is not going through the other leg and being wastedWhy is energy on the neutral not performing work?
Yes, the difference being returning to the head through the other leg or through the neutral.Doesn't all energy that leaves the head have to return to it?
You do you.I fell like I should probably let you off the hook at this point.
I was asking those questions to make the point that the return path doesn't matter in regards to fuel efficiency or energy waste. The engine won't be loaded any differently whether a 5kw load is split equally between L1 and L2 or if its all on L1 and N (assuming it can support 5kw on L1 or L2 singularly). The energy on the neutral isn't wasted. It just follows a different path. Do I recommend doing running with extreme unbalanced loads? No. That said, it happens.
Any energy that doesn't do work is dissipated how? Heat. Running loads with a PF less than 1 does cause the generator head to run hotter than if the same power was being generated and the load's PF was 1. PF is an example where the energy you generate and the energy the load uses to to work is not equal and the difference in the two is wasted (as heat). To go back to the example above, If we had 30 amps @ 120v of neutral current being wasted (as heat), the generator head would quickly overheat and fail. Neutral current isn't wasted energy. This could be an error in semantics but I wanted flush it out some to clarify.
Sorry to sideline the original post. I hope this is information that is helpful.
Howdy,I am assuming it won't hurt to run them unbalanced: thinking of adding a few more 110 off of the third phase and have a 220 50 amp plug (overkill) going to a distribution block
I'm not quite following.As a generator is loaded the engine has to work harder to fight the magnetic flux. If you load 1 leg (or 2 legs) the engine is working harder to keep up. Now the unbalanced part, the unbalanced current returns to the source (generator head) via the neutral (its being wasted and not performing any useful work).
Mathematically (using a single phase in the example for easier math) if you have 2 120 volt loads 1 50 amp and 1 20 amp on separate phases there is a 30 amp unbalance which is being directed back to the head. The engine is working hard enough to keep that 50 amp load up. Now if the loads were balanced there would be an even 35 amps on each leg, so the engine would have to only work at keeping 35 amps of field going. Same amount of work being done but the engine isnt working as hard.
I'm not quite following.
If a generator is 3-phase, operating at a fixed speed (1800 rpm), then power absorbed is a function of torque on the rotor. Torque is a function of the combined load on the 3 phases. For example, shouldn't a 15kW generator not load each phase at 5kW? (average)
Now if the loads were imbalanced, even if a single phase exceeded 5kW, say 7kw, 5kw, and 3kw, wouldn't the average torque load and therefore power absorbed still be 15kW? Now there would be fluctuation in torque as the field rotates, which would cause some inefficiencies.
Flow through the neutral conductor would be equal to the phase imbalance at any instant in time, but I wouldn't say the energy is wasted or causes additional load on the engine, the power just returns on a different path through the stator.
Wouldn't the bigger concern be a voltage imbalance between the phases? There is only one field coil shared between 3-phases, every load imbalance would cause a voltage imbalance.
As a load is applied the engine has to put out more effort to keep the rpm at the desired level. An unbalanced load will impact voltage to a small degree. Any unbalanced load goes back to the head on the neutral. The load carried by the neutral is energy that can be better spent, if it were completely balanced the current is used more efficiently then being wasted in the neutral. In the example I was giving earlier (more of a worse case and yes I have seen people do this with portable sets) 1 leg heavily loaded causing the engine to work harder and consume more fuel while the other leg was not being used as much. The simple point I was makeing is be mindful of what you hook and where. End of the day you do what you want and if you reduce your efficiently by having a high neutral current you have every right to. Have fun with it. Can you practically balance a load perfectly ? Not unless you are in a very well controlled environment. Should you make an effort to get close? Absolutely.I'm not quite following.
If a generator is 3-phase, operating at a fixed speed (1800 rpm), then power absorbed is a function of torque on the rotor. Torque is a function of the combined load on the 3 phases. For example, shouldn't a 15kW generator not load each phase at 5kW? (average)
Now if the loads were imbalanced, even if a single phase exceeded 5kW, say 7kw, 5kw, and 3kw, wouldn't the average torque load and therefore power absorbed still be 15kW? Now there would be fluctuation in torque as the field rotates, which would cause some inefficiencies.
Flow through the neutral conductor would be equal to the phase imbalance at any instant in time, but I wouldn't say the energy is wasted or causes additional load on the engine, the power just returns on a different path through the stator.
Wouldn't the bigger concern be a voltage imbalance between the phases? There is only one field coil shared between 3-phases, every load imbalance would cause a voltage imbalance.
I'm not quite following.
If a generator is 3-phase, operating at a fixed speed (1800 rpm), then power absorbed is a function of torque on the rotor. Torque is a function of the combined load on the 3 phases. For example, shouldn't a 15kW generator not load each phase at 5kW? (average)
Now if the loads were imbalanced, even if a single phase exceeded 5kW, say 7kw, 5kw, and 3kw, wouldn't the average torque load and therefore power absorbed still be 15kW? Now there would be fluctuation in torque as the field rotates, which would cause some inefficiencies.
Flow through the neutral conductor would be equal to the phase imbalance at any instant in time, but I wouldn't say the energy is wasted or causes additional load on the engine, the power just returns on a different path through the stator.
Wouldn't the bigger concern be a voltage imbalance between the phases? There is only one field coil shared between 3-phases, every load imbalance would cause a voltage imbalance.
1800 rpm is exactly 60 hs on a 4 pole generator (which this is). On a 2 pole gen head the engine rotates at 3600 rpms. (double the poles in the gen head, half the rpms), as long as it's a generator that is directly mounted to the engine output.how do i make sure the engine is set at 1800 rpm? is the 60 hertz about 1800?
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