Wind Turbine Power

quique

I have a wind turbine that I bought in TW.

Attachment not found.

Its rated at 1000W & 48V. I have a couple of questions...

1) The generator has a coupling with 3 wires. I understand that its because its three-phase. However, the cables have no markings and the coupling it self has 3 terminals with screws to hold on the the extension wires I must install. I have contacted the supplier which will respond by tomorrow but I wanted to run this by you guys...the recommended way to test it would be to actually mount the turbine and use a tester to determine which is which? Ive called my electrician to come find out for me, Im assuming he will only need a tester, right?

2) There is a wire that runs from the generator to the coupling. Its about 10" long and made up of 3 individual red wires. They look like AWG12 wires. But Im thinking, if Im going to run this for about 10m, wouldnt I loose a lot of power from the source to 10m downstream of DC current if I use such a thin wire? Im only used to solar panel and battery wiring where the cable has to be very thick, thicker than AWG8 or 6 and more. So if the turbine wires HAVE to be longer due to the fact that the wires must run down a very tall pole, why do they use what seems to be AWG12 wire from the generator to the coupling? Because its only 10"? But the terminals in the coupling are about the same size, they wouldnt accomodate anything thicker than AWG10 or 8 (pushing it).

3) What does three phase and single phase practically mean?

thanks guys

BB.

Re: Wind Turbine Power

IF this is a three phase turbine (with no internal rectifiers), then the labeling of the three phase wires does not matter.

You just connect the three wires to your three phase input rectifier (in any order) and you are done.

You can confirm by measuring the restance between all three wires (L1-L2, L2-L3, L3-L1). If the resistance is all the same (and flip the +/- leads of your DC based Ohm meter to confirm no diodes in circuits) you are fine. Be a bit careful when connecting and disconnecting the Ohm Meter--It passes a little bit of current into the coils on your turbine and when the leads are disconnected, the collapsing field in the coils may generate a few hundred volts and "bite" you.

Also, would check the resistance between LX and Frame Ground on the wind turbine. It is possible (but not likely) that one of the phases is grounded (more issues if you find a low resistance gun).

-Bill

ChrisOlson

Re: Wind Turbine Power

quique wrote: »

2) There is a wire that runs from the generator to the coupling. Its about 10" long and made up of 3 individual red wires. They look like AWG12 wires. But Im thinking, if Im going to run this for about 10m, wouldnt I loose a lot of power from the source to 10m downstream of DC current if I use such a thin wire?

No, AWG 12 should be fine for a 48V 1,000 watt turbine. Each phase of a three-phase generator being rectified to DC carries the peak current 2/3's of the time. So at 18 amps DC output if you put a clamp-on meter on one of the legs you'll only see 12 amps RMS on the wire.
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Chris

quique

Re: Wind Turbine Power

Thanks for all your replies.

Im just a bit confused by all the technical terms. I understand ac means alternating current, and that it is a result of the source of the current. If the source generates the current by rotating coils around a magnetic field, the current will have alternating "polarity"? because the flow of electrons changes direction every 60 secs.

I think understand dc means direct or continuous current which means the electron flow is always constant in one direction.

Then when single and threephase came into my life, i read up on it and i kinda understand the meaning, the whole 120 degree offset because of the way its produced etc, but does that mean there is single/three phase ac and dc, or just ac?

And if a turbine actually is a motor that spins coils around a magnet, then what it should produce is 48V ac, right? Not 48V dc like a large solar panel would produce?

ChrisOlson

Re: Wind Turbine Power

All generators produce AC (alternating current). DC generators have a very ingenious mechanical rectifier device called a commutator and brushes. However most generators will convert the AC power they produce to DC with the use of a solid state rectifier, or diode bridge.

AC current is output in the form of a sine wave that goes to full positive, then to zero and then to full negative, alternating with the current frequency. The frequency of any generator is determined by the number of poles it has times the rpm divided by 120. So the frequency of a permanent magnet wind turbine generator producing so-called "wild AC" will constantly vary, depending on the angular velocity (rpm) of the turbine's rotating assembly.

DC current is as you surmise - it is current that flows in only one direction and does not alternate between positive and negative. Transmission of DC current is more efficient than AC because of capacitance in wires. Being AC is constantly changing polarity the wire has to be "charged" and "discharged" with every AC cycle. With DC it is only "charged" once and electrons flow in one direction constantly. However, wire capacitance only really becomes an issue with very long wire runs.

When you measure AC current (amps) or voltage most meters are going to show a RMS (Root Mean Square) value. The peak values, that you will see when measured on the DC side of a rectifier are higher than what the AC RMS values are. So a three-phase generator producing 10 amps AC RMS per phase will produce ~14.9 amps of DC current. And the same generator producing 50 volts RMS per phase will deliver 69.2 volts DC. This is the difference between the actual peak value and the Root Mean Square value that most AC meters will measure.

The term "phase" only applies to AC. Common worldwide are single and three-phase AC systems. Three phase is merely three single phase windings separated by 120 electrical degrees and it is more efficient for power transmission than single phase systems. It is possible to also have two-phase, four-phase, five-phase and so on. But there is no real advantage in polyphase systems one you get over thee-phases, so they are very rare.
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Chris