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Coil Design #2
By WXYZCIENCE, Section Mechanical Posted on Thu Mar 8th, 2007 at 07:32:32 PM MST
Answers

This coil research has me interested in coil efficiency. The wave forms below were the same across both coils. The first 120 hz (2400 rpm 6 pole)

Next 400 hz (6000 rpm 6 pole)

Dc Resistance Test: The two coils were placed into a series circuit with an applied emf of 12v dc. The current was limited to 2.70 amps by a automotive 12v tail light bulb. Coil #1 .105v dc, Coil #2 .117v dc. The resistance for Coil #1 .038 ohms, Coil #2 .043 ohms.

Inductance Test: The next test that was done on the coils was an inductance test. Coil #1 .051 mh (400hz = .128 ohms) Coil #2 .041 mh (400hz = .102 ohms)

I will have to do more tests to confirm the readings. I will mount both coils with temperature sensors and exact loads. This next test will give me side by side readings for more accuracy.
Joseph.

Coil Design #2 | 4 comments (4 topical, 0 editorial)

Re: Coil Design #2 (3.00 / 0) (#1)
by Flux on Thu Mar 8th, 2007 at 01:33:44 PM MST
(User Info)

Not sure how you measured inductance but I am very surprised that there is much difference at 400Hz.

I am not sure what use inductance is going to be anyway, you will never manage to measure leakage reactance which is the thing that matters.

Re: Coil Design #2 (3.00 / 0) (#2)
by Nando (nando37-at-tx-dot-rr-dot-com Correct theanti-spam) on Thu Mar 8th, 2007 at 02:14:02 PM MST
(User Info)

What are you trying to really get ?.

Can you measure the inductance ?.

Your measurements, the way you are doing it, will require such precise equipment and calorimetry that for sure you do not have.

If you want to get the efficiency of the coils, define the wire size, the inductance and the stray capacitance of it, then you may be able to calculate where the frequency where the efficiency starts to decay.

For your AXIAL generators and the frequency generated, the coils winding have to be quite high at least one order of magnitude, point to consider then.

Unless you are aiming for more than 2000 Hz then put aside your idea.

At 12000 RPM, 2 poles produces 200 Hz, 4 poles 400 Hz, 6 poles 600 Hz.

Can you detail your reasoning for such experiment ?.

Nando

Re: Coil Design #2 (3.00 / 0) (#4)
by WXYZCIENCE on Fri Mar 9th, 2007 at 02:43:52 PM MST
(User Info)

nando, My first tests with the #14 guage wire coil the temperature rise started at 11c and went to 37c. The load was ~150 watt. (light bulb). This test was over a period of ~ half an hour. The second coil 4 x #21guage same load never reached 15c.

I wanted to find out why.

Here is what I have come up with:

I would not recommend building a coil with a single conductor for any air stator application.
Heat is a major factor regardless of the speed in axial design.
Shorting coils to shutdown turbine produces to much destructive vibration on the structural components.

My opinion: Tests on this high speed design aggravated the long term and sustained effects that all large axial designs will encounter. More so in conditions where elevated ambient temperature is sustained.

My suggestion: Someone building a larger Axial should try multiple strand coils to see if it will improve the operational temperature rise.

Can you measure the inductance ?.
I have access to a real good inductance meter.Thanks nando for your input. I will keep posting the results as the steam turbine and the high speed axial meet probably this summer.
Joseph

[ Parent ]

Re: Coil Design #2 (3.00 / 0) (#3)
by willib (willibur at comcast dot net) on Thu Mar 8th, 2007 at 08:55:04 PM MST
(User Info) http://www.njwind.com/webcam.html#

nice looking waveforms
Carpe Ventum (seize the wind)

Coil Design #2 | 4 comments (4 topical, 0 editorial)

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