Harmonics on neutral ?

[neher]

Lets say I have a switchboard that requires ONLY 3 Phase loads, transformer, UPS, Motors, ETC. ( no neutral is required at all)
Now lets say I am feeding this from a generator where I have 4 wires from the alternator ABCN connected to the aforementioned switchboard.
the N of the generator alternator is Bonded to ground inside of the aforementioned switchboard but NOT at the generator location.

The 3 phase loads that are feeding from the switchboard are non-linear and have a fairly "dirty" harmonic profile.

The question is will i see any harmonic loads on the neutral conductor between the main service and the generator?

can someone point me to a white paper or other documentation that clarifies this point either way?

thank you

-Deepro

 

[davidbeach]

Yes. The generator will produce some harmonics all on its own. There may also be some coupling between the phase conductors and the neutral.

 

[neher]

let take the generator and capacitance coupling the the equation.

The question is will i see any harmonic loads on the neutral conductor between the main service and the generator?

can someone point me to a white paper or other documentation that clarifies this point either way?





When an elephant is in trouble even a frog will kick him.

 

[PHovnanian]

will i see any harmonic loads on the neutral conductor

Negligible. By 'harmonic loads' I assume you mean current harmonics. Other than its bonding to ground, the generator neutral is open circuited as none of the loads are connected to it and cannot return their harmonic currents to the source through it.

There may be some capacitive coupling, as David suggested, between phase and neutral. But this impedance is quite high and the resulting currents will be low. And not trivial to calculate, given the unknowns in cable layout, capacitance, harmonic voltages generated by load and generator and their internal impedances to these harmonics.