FAI-F1D
Free Flight Indoorist
A while back I ordered an HXT 2730 3000 kv "Silver Wonder" for a limited motor run free flight model (E36 class). As described in this thread, I found out that they sent me the wrong motor: http://forum.flitetest.com/showthread.php?14884-HXT-3000-kv-is-it-really
After a little investigation, I realized the windings were terminated in wye format. You can push the kv back to the desired range by re-terminating the windings into delta format.
So here's the motor as it came to me:
Removing the motor mount lets us get to the relevant areas and take a closer look:
Now we can see that the leads come in to the three phase and the ends of each phase are soldered together (the little bit covered in shrink tubing up by the mount mast).
For clarity, I've pulled out that common termination and removed its shrink tubing. WARNING: it's now non insulated because of the exposed solder!
That common termination is what defines this as a wye layout. Current has to flown through one phase and back out through another, which increases torque. Delta format isolates the phases, which decreases torque, but reduces phase resistance by 50%, thereby increasing the kv of the motor. Here's a diagram explaining the wye configuration:
We want to convert it to this layout:
It is absolutely critical that we do not short out a phase either by an incorrect termination pattern or by scraping insulation off the wires. This is why you will see repeated warnings about potential pitfalls here.
Now go back to that common termination point...
Carefully pull it off to the side. Next strip back the insulation on the leads to expose more wire for the work:
Desolder the common termination point and pull the wires away from each other. You need to keep them organized so you can reference the ordering of the phases.
Use your multimeter to track down which phase is which. As you can see, the lead and its end are at opposite sides of the pattern. Make a record of this and go back to the wiring diagram.
Once you've figured out which end is going to attach to which lead, scrape back the insulative coating at the base of each lead and wrap the ends around the leads they go to. Go back and check the leads. tapping into ANY pair of two leads should provide a closed circuit. If you have a short, you'll also have an open circuit across one of your three possible lead-lead combinations. Notice I have not soldered these together yet.
This next step is critical. BE CAREFUL. You can easily fry your ESC and/or burn out a phase at this point. Carefully arrange the terminations so that they are away from contact with the motor mount mast and each other. Now carefully plug everything into your ESC and arm the system.
VERY CAREFULLY advance the throttle. If there are any sparks or excessive jittering of the throttle, drop it back to zero immediately. It only takes a second for a short to cook your equipment! Since the terminations are not soldered yet, there will be some tiny sparks in the terminations. You've been warned.
If anything isn't right, go back and recheck that you've paired the terminations correctly. Refer to diagrams as needed. I was fortunate in that I paid close enough attention to get it right the first time. Proper care will ensure that you achieve the same outcome.
Once satisfied, I soldered the terminations to make it permanent.
And now time to insulate those terminations...and find out that the bullet connectors are large enough that I have to remove them to fit the shrink tubing.
With the bullets removed, the shrink tubing goes in place and everything is insulated.
Now wait! Don't put the bullets back on just yet. Put a larger piece of shrink tubing on that will bundle the three insulated terminations together (refer to the first photos to see what this looks like) so that moving the wires around won't put undue stress on the joins and break a connection.
Now you can put the bullets back on.
In test runs without the prop, the motor was audibly higher pitched when running, a clear sign that it worked out. The flying field verified this.
My climb pattern went from this: https://www.youtube.com/watch?v=Z5THIcU3Yco
to this: https://www.youtube.com/watch?v=pSrzH-dVumI
After a little investigation, I realized the windings were terminated in wye format. You can push the kv back to the desired range by re-terminating the windings into delta format.
So here's the motor as it came to me:
Removing the motor mount lets us get to the relevant areas and take a closer look:
Now we can see that the leads come in to the three phase and the ends of each phase are soldered together (the little bit covered in shrink tubing up by the mount mast).
For clarity, I've pulled out that common termination and removed its shrink tubing. WARNING: it's now non insulated because of the exposed solder!
That common termination is what defines this as a wye layout. Current has to flown through one phase and back out through another, which increases torque. Delta format isolates the phases, which decreases torque, but reduces phase resistance by 50%, thereby increasing the kv of the motor. Here's a diagram explaining the wye configuration:
We want to convert it to this layout:
It is absolutely critical that we do not short out a phase either by an incorrect termination pattern or by scraping insulation off the wires. This is why you will see repeated warnings about potential pitfalls here.
Now go back to that common termination point...
Carefully pull it off to the side. Next strip back the insulation on the leads to expose more wire for the work:
Desolder the common termination point and pull the wires away from each other. You need to keep them organized so you can reference the ordering of the phases.
Use your multimeter to track down which phase is which. As you can see, the lead and its end are at opposite sides of the pattern. Make a record of this and go back to the wiring diagram.
Once you've figured out which end is going to attach to which lead, scrape back the insulative coating at the base of each lead and wrap the ends around the leads they go to. Go back and check the leads. tapping into ANY pair of two leads should provide a closed circuit. If you have a short, you'll also have an open circuit across one of your three possible lead-lead combinations. Notice I have not soldered these together yet.
This next step is critical. BE CAREFUL. You can easily fry your ESC and/or burn out a phase at this point. Carefully arrange the terminations so that they are away from contact with the motor mount mast and each other. Now carefully plug everything into your ESC and arm the system.
VERY CAREFULLY advance the throttle. If there are any sparks or excessive jittering of the throttle, drop it back to zero immediately. It only takes a second for a short to cook your equipment! Since the terminations are not soldered yet, there will be some tiny sparks in the terminations. You've been warned.
If anything isn't right, go back and recheck that you've paired the terminations correctly. Refer to diagrams as needed. I was fortunate in that I paid close enough attention to get it right the first time. Proper care will ensure that you achieve the same outcome.
Once satisfied, I soldered the terminations to make it permanent.
And now time to insulate those terminations...and find out that the bullet connectors are large enough that I have to remove them to fit the shrink tubing.
With the bullets removed, the shrink tubing goes in place and everything is insulated.
Now wait! Don't put the bullets back on just yet. Put a larger piece of shrink tubing on that will bundle the three insulated terminations together (refer to the first photos to see what this looks like) so that moving the wires around won't put undue stress on the joins and break a connection.
Now you can put the bullets back on.
In test runs without the prop, the motor was audibly higher pitched when running, a clear sign that it worked out. The flying field verified this.
My climb pattern went from this: https://www.youtube.com/watch?v=Z5THIcU3Yco
to this: https://www.youtube.com/watch?v=pSrzH-dVumI
