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HelicopterMain Discussion › Current from ESC to Motor ?
05-28-2013 07:08 PM  4 years agoPost 1
Bouchah

rrKey Veteran

Willow Spring, N. Carolina USA

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Im working on a Trexs 550e V2, replacing the stock Aligh 70 Amp ESC with a Castle Talon 90 Amp, still keeping the stock MX600 motor.
The Talon ESC does not have any sort of motor leads coming off of it and the leads on the motor are too short to reach the ESC. Looking at the size wire that is on the 70 AMP ESC, I am wondering how it handles the Amp draw that it does. If 10 AWG wire is rated @ 30 Amps, how are we getting away with this small of a gauge wire? Is the Amp draw between the battery and the ESC the same as between the ESC and the motor?

What gauge wire should I use between the motor and ESC?

ALIGN ESC SPECS
Continuous current:70Amps with porper air flow
Surge current:110Amps(5sec)
Supporting motor types:2~10 pole in/outrunner brushless motors.
Supporting maximum RPM:2poles=>190,000rpm;6poles=>63,000rpm
Supporting input voltage:5.5V~25.2V
Supporting battery types: Li-ion/ Li-poly 2~6 cells
BEC output voltage: 5-6V step-less adjustment
Continuous current 3A; Burst current 5A
Size:65X31X18mm
Weight:72g

MOTOR SPECS
Input voltageC11.1V-50.4V
Max continuous current:75A/125A(5sec)
Max output power:3300W/5500W(5sec)
KV value:510KV
Dimension: spindle Ö6xÖ45x59mm
Weight: 340g (prox.)

Blade 130x (5)
Trex 550 V2 (18)
Shuttle ZXX
Freya Xspec (20)

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05-28-2013 10:30 PM  4 years agoPost 2
dkshema

rrMaster

Cedar Rapids, IA

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? Is the Amp draw between the battery and the ESC the same as between the ESC and the motor?
Yes. There is nothing else in the circuit between the battery and the motor where current is magically produced.

How are we getting away with it? It is not continuous current at 70 amps or 90 amps or whatever the rating of the ESC happens to be.

The average current is well within the current carrying capability of the wires, and as the wires are relatively short and large gauge, the IR drop is negligible, and little self-heating occurs.

The motor itself does not have 00 gauge wire, it is quite content with the leads it has. Use the same gauge wire as the motor, and keep it short.

Perhaps rearrange the ESC placement and see if you can get the motor to plug into the ESC.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

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05-28-2013 11:01 PM  4 years agoPost 3
Bouchah

rrKey Veteran

Willow Spring, N. Carolina USA

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Thanks for the reply,
Perhaps rearrange the ESC placement and see if you can get the motor to plug into the ESC.
I dont think that is possible, the motor leads are about 2", and the ESC only has female plugs on it. The only place the ESC could go to direct connect to the motor would be maybe under the battery tray. I really dont want to put it there, my first crash I experienced with this bird was nose first, took out the tray and the battery. Guess I will extend the wires a few inches.

Looking at the specs of the ESC it says continuous current of 70 amps, max 110 amps, that still looks like the wire should be bigger, but I guess these motor ESC developers know what they are doing, Hopefully!

Thanks again,
Howard

Blade 130x (5)
Trex 550 V2 (18)
Shuttle ZXX
Freya Xspec (20)

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05-29-2013 12:34 AM  4 years agoPost 4
dkshema

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Cedar Rapids, IA

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You really don't want 4 gauge or 2 gauge or 0 gauge wire between you electronics on a heli.

Again, just because it SAYS continuous, you don't SEE continuous peak or max current ever delivered in the system.

The wires are short, very little copper loss occurs, and the conductors are more than adequate for the purpose.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

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05-29-2013 12:59 AM  4 years agoPost 5
red_z06

rrProfessor

Dumont, NJ

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30amp rating for the 10awg is an extremely conservative number for household hookup wire using typically PVC jacket that melts at fairly low temps.

10awg silicone jacketed wires carry 140amp rating. That is continuous and depending also on cooling condition.

One major difference between PVC and silicone is that PVC will melt as it is a thermoform material that does not change chemical properties after being formed (hence melt and can be reformed), while silicone is a thermoset/cured material that will undergo changes in chemistry and can not be melted. It will char but never melt.

For this reason, silicone jacketed wires carry much higher current rating and typically are not used for household hookup wiring. Typically, when the over current occurs, either your connector housing or solder will melt before silicone jacket degrades.

www.JustinJee.com

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05-29-2013 10:11 AM  4 years agoPost 6
red_z06

rrProfessor

Dumont, NJ

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For Talon, you can use 12awg silicone jacket wire too. It is rated at 88amps.

www.JustinJee.com

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05-29-2013 12:02 PM  4 years agoPost 7
Ronald Thomas

rrMaster

Gainesville, Fl, USA

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Also the amount of current used will be distributed among the 3 leads going to the motor so no one lead will have the full rating, just 1/3 of it...

Team MikadoUSA 480XXTreme, 550SX, 600SX, 700XXTreme, 800XXTreme!!

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05-29-2013 12:34 PM  4 years agoPost 8
red_z06

rrProfessor

Dumont, NJ

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Also the amount of current used will be distributed among the 3 leads going to the motor so no one lead will have the full rating, just 1/3 of it...
Actually it is 2/3

Circuit path is a-b, b-c, a-c. So, any given wire will see the current 2/3 of the time.

www.JustinJee.com

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05-29-2013 12:53 PM  4 years agoPost 9
Ronald Thomas

rrMaster

Gainesville, Fl, USA

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True Sorry

Team MikadoUSA 480XXTreme, 550SX, 600SX, 700XXTreme, 800XXTreme!!

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05-29-2013 01:43 PM  4 years agoPost 10
dkshema

rrMaster

Cedar Rapids, IA

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Also the amount of current used will be distributed among the 3 leads going to the motor so no one lead will have the full rating, just 1/3 of it...
Actually it is 2/3
Circuit path is a-b, b-c, a-c. So, any given wire will see the current 2/3 of the time.
Both are WRONG.

Sorry, if the motor is consuming 30 amps at a given point in time, BOTH windings that are energized see the same number of amps -- 30. Both windings carry the full current present in the motor at any given point in time.

One of the three leads is tied to the high side switch to + battery volts, one of the leads is tied to the low side switch to ground. Whatever current enters the + side MUST also exit the motor to ground. The third winding is not energized and there is no current path through it. There is no current storage, splitting, diversion, or other physics defying phenomenon going on inside the motor.

Whatever enters 'a' exits through 'b' (or into 'b' leaves through 'c', or into 'a' leaves through 'c' ) in the commutation sequence noted above.

That is just the "steady-state, average" DC current. Starting the motor under a load sees instantaneous phase currents that exceed the steady state average by several times; momentary currents in excess of 100 amps are not out of the question, especially in the bigger motors and bigger helicopters.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

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05-29-2013 03:50 PM  4 years agoPost 11
Ronald Thomas

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Gainesville, Fl, USA

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One of the three leads is tied to the high side switch to + battery volts, one of the leads is tied to the low side switch to ground. Whatever current enters the + side MUST also exit the motor to ground. The third winding is not energized and there is no current path through it. There is no current storage, splitting, diversion, or other physics defying phenomenon going on inside the motor.
Whatever enters 'a' exits through 'b' (or into 'b' leaves through 'c', or into 'a' leaves through 'c' ) in the commutation sequence noted above.
I am a little confused, I don't see how that differs from what Red said. Please explain...so are you saying that all three leads are carrying the full load? If only two are energized at any given time, how is the third lead carrying load as well? Sorry for my ignorance.....

Team MikadoUSA 480XXTreme, 550SX, 600SX, 700XXTreme, 800XXTreme!!

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05-29-2013 03:56 PM  4 years agoPost 12
dkshema

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Cedar Rapids, IA

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Two leads at any time are energized. The third is open. Current cannot flow into, or out of, an open conductor.

The current path, say when the commutation sequence is for current to flow from 'a' to 'b' is through those two wires.

If the motor requires 30 amps at that point in time, 30 amps flows through into terminal 'a' and out through terminal 'b'.

The two energized leads carry 100% of the required current, not 2/3 of it.

The third lead has no path for current to flow, as it is not connected to either +V or ground. It is floating at that point in time.

The majority of motors out there for sale are Y-wound (WYE), not Delta wound.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

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05-29-2013 04:03 PM  4 years agoPost 13
red_z06

rrProfessor

Dumont, NJ

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Both are WRONG.
Arrrgg! I'm doing it all wrong.

Do you think I should redesign the motor that will go into the medial device (soon to go to FDA approval)?

.
.
.
.
.
.
.
.

All kidding aside, I look at the phase current on my motor design through an oscilloscope on a daily bases while fine tuning my motor design. It is not designed for power but for absolute efficiency.

In a simplistic way, Wye wind looks like below.

The current can flow from A-B,B-A(reverse) or A-C,C-A, or B-C, C-B. Whether it goes through two coils with common node in between for Wye or one coil only in delta makes no difference.

Lets assume only commutation pwm with no throttling pwm. 30amp input goes through any one of A-B, A-C, or B-C circuit. It is true (assume zero rise and drop time during the power on) that 30amp input is seen by the motor. But, that current goes through 3 phases in sequence and you will see that each coil is energized for exactly 2/3 of the time only. Because the 30amp input is seen only 2/3 of the time, the average current on each phase wire is only about 20amps.

BTW, this discussion has nothing to do with start-up peak current.

www.JustinJee.com

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05-29-2013 04:06 PM  4 years agoPost 14
Ronald Thomas

rrMaster

Gainesville, Fl, USA

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That is what I love about this hobby, always learning!!!!

Team MikadoUSA 480XXTreme, 550SX, 600SX, 700XXTreme, 800XXTreme!!

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05-29-2013 04:13 PM  4 years agoPost 15
dkshema

rrMaster

Cedar Rapids, IA

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I think we are splitting hairs. At any time, two windings are connected to their respective input/output. During that period, both windings see the full current. There is no other place for it to go. The AVERAGE or perhaps RMS current is lower as the commutation sequence progresses. Stall that motor, turn on the two windings, measure the current in all three leads, make sure your current limit circuits work.

You DO have to design for other than average current in your controller and the motor.

-----

Your medical device and my Horizontal Stabilizer Pitch Trim systems will both function well and keep us all safe.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

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05-29-2013 04:47 PM  4 years agoPost 16
red_z06

rrProfessor

Dumont, NJ

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What exactly do you mean both? You can only turn on any one of A-B, B-C, or A-C phase at any given time. But, in reality there is actually a small dead band of <100ns when all are off as the controller chip has a preprogrammed delay so no two gate path is on at the same time.

For wire gauge selection purposes, there are 4 circuits.

Battery + -,

A-B
B-C
C-A

Phase wires can be designed to handle 2/3 of the input side of ESC current capacity.

www.JustinJee.com

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05-29-2013 05:24 PM  4 years agoPost 17
Civerad

rrVeteran

Cincinnati, OH, USA

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If 10 AWG wire is rated @ 30 Amps, how are we getting away with this small of a gauge wire?
I think this is a rating for a 120 volt household wiring. I could be wrong.

But I use 10 AWG wire on my Talon to extend the leads to the motor and you should be fine. The female plugs on the ESC can get loose and I've had one plug come off while flying so make sure you secure those.

John D.
Team Align
H.A.W.K.S. - Cincinnati, OH
RIP Roman Pirozek Jr.

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05-29-2013 05:37 PM  4 years agoPost 18
red_z06

rrProfessor

Dumont, NJ

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BTW, how does
Both are WRONG
with capital WRONG turn into
I think we are splitting hairs
?

You are keep saying two windings are connected. There are three circuit paths with only one path energized at any given moment not two with the third node in float.

www.JustinJee.com

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05-29-2013 06:09 PM  4 years agoPost 19
JKos

rrProfessor

Redondo Beach, CA

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There are three circuit paths with only one path energized at any given moment not two with the third node in float.
I'm reading you both saying the same thing in this respect.

- John

RR rules!

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05-29-2013 06:17 PM  4 years agoPost 20
red_z06

rrProfessor

Dumont, NJ

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John

Take a look at the delta wind and see what happens when two windings are powered. This is not possible.

www.JustinJee.com

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HelicopterMain Discussion › Current from ESC to Motor ?
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