Harmonic Loads

[wannabe]

what is considered a harmonic load

 

[iwire]

Re: Harmonic Loads

Originally posted by wannabe:
what is considered a harmonic load

I think you may be asking about nonlinear loads, a nonlinear load creates harmonic currents.

Nonlinear Load. A load where the wave shape of the steady-state current does not follow the wave shape of the applied voltage.

The current leads or lags the voltage sine wave instead of following it.

Electronic equipment, electronic/electric-discharge lighting, adjustable-speed drive systems, and similar equipment may be nonlinear loads.

[ August 08, 2005, 06:44 AM: Message edited by: iwire ]

 

[wannabe]

Re: Harmonic Loads

thank you

 

[charlie b]

Re: Harmonic Loads

Bob, you have a dood definition of "non-linear" and a good list of non-linear loads, but I fear that I must disagree with your example, your explanation, of the term "non-linear."

Nonlinear Load. A load where the wave shape of the steady-state current does not follow the wave shape of the applied voltage.

Good definition. But please note that it is talking about the SHAPE of the wave form, not its timing. If you start with a clean sine wave for voltage, and if the current looks like a square wave (or more likely it will look like a messy collection of spikes and dips that only vaguely follows a sine wave pattern), then this fits the definition of non-linear.

Originally posted by iwire: The current leads or lags the voltage sine wave instead of following it.

If the current is a pure and clean sine wave, and if it lags the voltage (itself also being a pure and clean sine wave) by some amount of time, then you would not be looking at harmonics, and the load would not be "non-linear." Rather, what you would have here is a linear, but inductive, load, such as a motor.

 

[iwire]

Re: Harmonic Loads

Thanks, I learned something new.

 

[iwire]

Re: Harmonic Loads

By the way, the correct parts of my post I liberated from the NEC, the incorrect parts where all me.