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Author Topic: Arming Plug causing ESC damage?  (Read 14613 times)

Online Peter Germann

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Arming Plug causing ESC damage?
« on: February 25, 2016, 03:35:52 AM »
I believe to remember having read (here?) pulling an arming plug (disconnecting the battery) at full RPM may possibly cause damage to the ESC. May I please ask experts to comment on this?

Thank you and kind regards
Peter Germann

Offline Wolfgang Nieuwkamp

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Re: Arming Plug causing ESC damage?
« Reply #1 on: February 25, 2016, 09:24:55 AM »
Peter,

When
1. you are using a large propeller
2. the current limiting feature is disabled

it could be that the back EMF voltage over the windings burn one or more of the Power Mosfets of the output stage of the ESC.

May I suggest to ask your question to the technical people of Castle Creations? It may take two weeks, but you will get a competent answer.

Regards,

Wolfgang

Offline Tim Wescott

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Re: Arming Plug causing ESC damage?
« Reply #2 on: February 25, 2016, 10:41:56 AM »
Hey Peter:

Short answer: maybe yes, maybe no.

Long answer: uh, it's complicated.  Basically you can't just turn off the current to a motor in an uncontrolled way -- doing so will lead to nasty voltage spikes.  You can't turn off a transistor in those things too slowly, or it'll burn up (switching amplifiers use teeny transistors because they're either all the way on or all the way off.  If they stay in between for too long -- POOF!)

A circuit designer that cares could, I think, make an ESC that would shrug that off.  But it would have to be done it on purpose, which means that either the circuit designer does it on the sly, or everyone in the management chain cares enough to budget the time and money to make it happen.

What it all boils down to is -- ask the ESC manufacturer.  Or, if it's a cheap ESC that you bought for 30 Euros, and that looks exactly like a dozen other cheap ESCs except for the brand name, then assume that if a bad thing can happen it will.

If someone is willing to pay me about $60,000 I'll sell them an ESC that's robust to all of that, plus regulates at least as well as the original Jeti Spin 66, and maybe even tolerates being shoved into the grass at random times while spinning at top speed.  I'll throw in a built-in Hubin-style timer for free.  The next ten one will cost about $100 each.  For $100,000 up front, I'll just sell them for $100.  Piece prices will continue to go down as guaranteed volume goes up.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Igor Burger

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Re: Arming Plug causing ESC damage?
« Reply #3 on: February 26, 2016, 04:48:41 AM »
I believe to remember having read (here?) pulling an arming plug (disconnecting the battery) at full RPM may possibly cause damage to the ESC. May I please ask experts to comment on this?

Thank you and kind regards

yes, it is known issue, the rason is that the current in coil has some energy, that energy must go somewhere when transistor cuts the current, you will see that energy as current continuing to flow somewhere after cutting of - if there was no "where" you will see known voltage peak ... but there IS where to flow, there are diodes for that purpose in every FET transistor, unfortunately all ESCs for BLDC are designed to forward that current back to battery (old DC ESCs are constructed different, diode feeds motor winding, not battery) , if you disconnect that battery during run, there will be no "where" it will cause voltage peak which will certainly overrride max Fet voltage

so the situation is clear, however there are 2 things which can make it safer:

1/ if max voltage for ESC his high enough - for example if you use 6cell ESC with 2 cell battery, ecs will highly probably survive

2/ high quality low ESR capacitors on battery leads - they will catch that current, they are usualy good enough in new ESC (at least on well designed ESCs) but they dergrade in time, so old ESC can fail also

so my recomendation - do not use safety plug for regular cutting motor off, it is safety plug for emergency when cost of ESC is not an issue, not cut off plug ... in normal situation, remove it only when motor does not run ... that is why I recommend to have normal low voltage switch on ESC like you can see on Spins 66, or timer with cut off function

Online Peter Germann

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Re: Arming Plug causing ESC damage?
« Reply #4 on: February 26, 2016, 07:14:00 AM »
Thank you all. As suggested,I have submitted the matter to Castle today:

"At this point in time the FAI rule makers are evaluating both the safety gain and / or  a possible technical risk resulting from making the installation of arming plugs (between battery and ESC) compulsory for Control Line electric speed models, class F2G. As I am involved in this decision finding process, I would like to ask the following question: Arming plugs sometimes used in Control Line model airplanes are, when being pulled while the motor runs full RPM, disconnecting the battery from the ESC. My question is whether such sudden disconnect could possibly damage the ESC?"

I will publish their response here. Igor, could we perhaps get a related statement from Jeti, too?

rgds, Peter

Peter Germann

Offline Paul Smith

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Re: Arming Plug causing ESC damage?
« Reply #5 on: February 26, 2016, 05:46:38 PM »
It seems like your theory may be correct.  So don't pull the plug at full throttle.

We still need protection from high powered motors that can start themselves for no known reason.  I, for one, do not trust gizmos and circuits devised by modelers.

This is akin to the wrist strap on the handle.  While I don't plan to let go of the handle myself, I feel a bit safer if others wear the thong.
Paul Smith

Offline Tim Wescott

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Re: Arming Plug causing ESC damage?
« Reply #6 on: February 26, 2016, 08:13:37 PM »
so my recomendation - do not use safety plug for regular cutting motor off, it is safety plug for emergency when cost of ESC is not an issue, not cut off plug ... in normal situation, remove it only when motor does not run ... that is why I recommend to have normal low voltage switch on ESC like you can see on Spins 66, or timer with cut off function

Most ESCs will stop if their signal is cut off, so you could wire a switch into the power lead to the ESC.  If you were going to make it part of the safety equipment on an electric plane you'd probably want to have guidelines for calling it out, such as a big red arrow against a contrasting background saying "Safety Off".

I suspect that something bad enough to make you want to cut power to the motor, but not so bad that it's already smoked the ESC, could probably be dealt with by holding the plane until the timer runs out.  Or just shove the nose of the plane into the ground -- that'll smoke the ESC, but if it's that important, c'est la vie.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Brett Buck

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Re: Arming Plug causing ESC damage?
« Reply #7 on: February 27, 2016, 10:35:56 AM »
Most ESCs will stop if their signal is cut off, so you could wire a switch into the power lead to the ESC.  If you were going to make it part of the safety equipment on an electric plane you'd probably want to have guidelines for calling it out, such as a big red arrow against a contrasting background saying "Safety Off".

I suspect that something bad enough to make you want to cut power to the motor, but not so bad that it's already smoked the ESC, could probably be dealt with by holding the plane until the timer runs out.  Or just shove the nose of the plane into the ground -- that'll smoke the ESC, but if it's that important, c'est la vie.

   I think if you try a full-power run on the ground, you will also cause damage, or at least something is going to get VERY hot. It's going to run the battery down in about 4 minutes.

     Pulling the plug while it is running is an emergency action and may very well break something. You sure do not want to do it unless you have to.

     Brett

Offline Tim Wescott

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Re: Arming Plug causing ESC damage?
« Reply #8 on: February 27, 2016, 12:58:14 PM »
I wonder if the little military drones that look like models use an ESC that's more rugged, or if they just don't worry about it.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Brett Buck

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Re: Arming Plug causing ESC damage?
« Reply #9 on: February 27, 2016, 03:08:40 PM »
I wonder if the little military drones that look like models use an ESC that's more rugged, or if they just don't worry about it.

  I don't know but you wouldn't normally encounter this problem anyway, since you normally control it with the regular low-level logic signals.

   The back-EMF issue is not trivial. I have seen transistor radios with 1200V ceramic capacitors to shunt inductive spikes around the output transistors, and if you put in 50V, they will blow in pretty short order. This with a VCC of a mere 6 volts, a 1/10th of a watt total power draw,  and an output transformer about the size of your thumbnail.

     Brett

Offline Paul Smith

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Re: Arming Plug causing ESC damage?
« Reply #10 on: February 28, 2016, 07:51:32 AM »
Just throw a rag into the prop.  That has always worked well for me.  It never hurt one of my engines and only slightly hurt the rag.
Paul Smith

Offline Carl Cisneros

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Re: Arming Plug causing ESC damage?
« Reply #11 on: February 28, 2016, 10:21:10 AM »
Paul;
you don't really want to do that (rag in the prop) with electric power. With glo/diesel or spark motors, yes, it works great.

With electric power and using some of the cheaper ESC's that do not normally have the over current shut off, the motor
will want to continue running, the current really shooting up to the moon, until the magic smoke is let out of the esc and also more than likely can and will damage the motor itself.


Carl
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Offline Tim Wescott

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Re: Arming Plug causing ESC damage?
« Reply #12 on: February 28, 2016, 01:39:27 PM »
Paul;
you don't really want to do that (rag in the prop) with electric power. With glo/diesel or spark motors, yes, it works great.

With electric power and using some of the cheaper ESC's that do not normally have the over current shut off, the motor
will want to continue running, the current really shooting up to the moon, until the magic smoke is let out of the esc and also more than likely can and will damage the motor itself.

I only fly electric RC (and design circuits -- hence, electric CL is too much like work).  But I'm assured by folks I trust that even the "good" Castle ESCs will quietly die if you stuff the plane into the ground at full throttle.  Presumably this applies to throwing a rag in the prop.

This is an oversimplification, but basically an IC engine has a fairly constant torque, and the speed rises until the prop is resisting that torque.  An electric motor being driven at a constant voltage* has a fairly constant speed**, and if you try to slow it down the torque (and current) will rise to keep it going that fast.  So a rag in the prop of an engine will just drag it to a stop.  A rag in the prop of a motor, unless it's using a very different sort of ESC, will pull tons of current and pop something.

* Which is what ESCs do, more or less.

** It's not a perfectly constant speed or we wouldn't need governors.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Online Peter Germann

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Re: Arming Plug causing ESC damage?
« Reply #13 on: March 02, 2016, 12:51:59 AM »
As per today, Castle Creations responds to my above question as follows:

Quote

…the answer is YES… This can cause the FETs to shut down in an abnormal state, meaning a contact inside the esc that should be open but is closed could cause a short between 2 of the phases and cause the esc to burn up.

I am familiar with the deans arming plugs.. They are fine when the motor isn't running but if the motor is running I would not recommend inserting while it is..

It may not happen overtime - but the possibility is there and could damage the esc. Not a possibility I think belongs in a mandatory rule book in my opinion.

End of quote

Peter G.
Peter Germann

Offline Brett Buck

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Re: Arming Plug causing ESC damage?
« Reply #14 on: March 02, 2016, 09:45:25 AM »
As per today, Castle Creations responds to my above question as follows:

Quote

…the answer is YES… This can cause the FETs to shut down in an abnormal state, meaning a contact inside the esc that should be open but is closed could cause a short between 2 of the phases and cause the esc to burn up.

I am familiar with the deans arming plugs.. They are fine when the motor isn't running but if the motor is running I would not recommend inserting while it is..

It may not happen overtime - but the possibility is there and could damage the esc. Not a possibility I think belongs in a mandatory rule book in my opinion.

End of quote

Peter G.


   I don't understand the last part. We are going to have this rule in the rule book whether emergency use breaks it or not, because you can't allow a chance of the motor running away by accident in the pits. The numerous reported incident of unexpected starts requires that.

   I am perfectly fine with the notion that pulling the plug or the battery connection while it is running will damage the ESC, and the fact that it might certainly doesn't surprise me.  That's not the use case. A normal use case is to insert the plug with the controller unpowered (by definition, not running), and pull the plug with the motor stopped. That had better not break it. Pulling the plug with it running is not anticipated and will only happen in the strangest of cases, in which case, damaging it is OK with me.

    Brett

Offline Tim Wescott

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Re: Arming Plug causing ESC damage?
« Reply #15 on: March 02, 2016, 10:49:53 AM »
What Brett said.  The arming plug is there to be pulled any time that someone won't have the airplane adequately restrained.  The intent of the rule in the US (as stated by Brett originally) only involves pulling or inserting the plug when the motor is stopped.  Pulling the plug when the motor is running is a distant corner-case, and, I suspect, may never happen at all.

If you want to shut the motor off under manual control, put a slide switch in the power line to the timer or use controller with a low-level arming switch.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Fredvon4

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Re: Arming Plug causing ESC damage?
« Reply #16 on: March 02, 2016, 12:22:07 PM »
I only tangentially know about arming plugs from adds I see in the RC catalogs and their use is for safety to prevent battery and ESC commands/power to make it to the electric motor

Knowing that modern motors are three wire, and I accept that the arming plug is just interrupting one of the three to prevent motor from starting
could this infrequent but real concern be negated by cutting power to any two of the leads(Weighs more) or (weighs even more) all three and thus if the plug is pulled while running, there would be no induced back voltage?
"A good scare teaches more than good advice"

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Offline Tim Wescott

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Re: Arming Plug causing ESC damage?
« Reply #17 on: March 02, 2016, 12:32:17 PM »
I only tangentially know about arming plugs from adds I see in the RC catalogs and their use is for safety to prevent battery and ESC commands/power to make it to the electric motor

Knowing that modern motors are three wire, and I accept that the arming plug is just interrupting one of the three to prevent motor from starting
could this infrequent but real concern be negated by cutting power to any two of the leads(Weighs more) or (weighs even more) all three and thus if the plug is pulled while running, there would be no induced back voltage?

The arming plugs required in the CL rules go in a battery lead to completely cut power to the electronics and motor.  Not in the motor leads.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Fredvon4

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Re: Arming Plug causing ESC damage?
« Reply #18 on: March 02, 2016, 12:48:41 PM »
AHA

not using electrics I did not know that...

Just for arguments sake a simple rule change to interrupt the Vcc to the motor seems to me to add the needed safety...BUT as evidenced here I am probably wrong

"A good scare teaches more than good advice"

Fred von Gortler IV

Offline Tim Wescott

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Re: Arming Plug causing ESC damage?
« Reply #19 on: March 02, 2016, 01:37:26 PM »
AHA

not using electrics I did not know that...

Just for arguments sake a simple rule change to interrupt the Vcc to the motor seems to me to add the needed safety...BUT as evidenced here I am probably wrong

There is no Vcc to the motor.  The ESC generates power for the timer (I assume that this is the "Vcc" you're talking about).  Interrupting that would make the timer stop sending pulses, and if the ESC were working correctly that would stop the motor.

The key phrase is "if the ESC were working correctly".  Cutting power to the timer protects the system from a faulty timer, but it does not protect the system from a faulty ESC that decides on its own that the timer is telling it to go.  Having a physical cut-off from the battery itself would mean that only an act of God would start the motor going when the arming switch is open.

Now, an ESC failing in that manner is probably less likely than a timer failing in that manner.  But ESC are complicated beasts, they have microprocessors on them, and with a system that complicated just about anything can happen.  Having that "just cut off everything" arming switch in there is a very inexpensive way of gaining absolute certainty that when it's used the plane won't fly.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Fredvon4

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Re: Arming Plug causing ESC damage?
« Reply #20 on: March 02, 2016, 02:19:36 PM »
Tim truly brother I am not trying to be thick

When I came back to modeling only game in town was RC and I sort of always wanted one as a kid so got talked into an Hobyco electric trainer.  There were all sorts of consumer cautions about testing with out a propeller on it because there are several modes where the motor ESC pair might arm and spin the prop

Later some one (deans?) made an "arming plug" that I just assumed interrupted the battery voltage before the ESC, or after, on one of the motor power leads

seemed to me ( for transmitter RC) to be fairly common to interrupt the power to the motor so the battery /ESC system was still hot and you could check aileron, rudder and elevator with out an armed motor

You guys doing electric stunt added in governors and timers either on board the ESC or separate to control your flight power omitting the need for a transmitter and the fiddling

If the safety need is to stop a self/inappropriately armed motor from spinning up the prop at the wrong time.

It would seem to me interrupting the current to the motor would be the preferred state for the arming plug

and I was wondering, in this configuration, if that would prevent the back EMF from letting the smoke out of the timer/ESC.... but did consider that the typical arming plug only interrupts ONE wire and a three wire motor would perhaps need at least two of the leads interrupted to prevent the back EMF

"A good scare teaches more than good advice"

Fred von Gortler IV

Offline Tim Wescott

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Re: Arming Plug causing ESC damage?
« Reply #21 on: March 02, 2016, 02:52:03 PM »
Tim truly brother I am not trying to be thick

Each of us is thick, in our own special way.

Putting the arming plug in one of the motor leads would probably keep the motor from starting up, but the ESC gets pretty cranky.  Depending on how the ESC handles the situation, it may not stop a running motor -- on most motors it would, but in theory a sophisticated enough ESC would just keep on truckin'.

Personally, on my RC planes I just plug a battery into the receiver to test out the servos, or I stand behind the plane, or I take the prop off.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline phil c

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Re: Arming Plug causing ESC damage?
« Reply #22 on: March 02, 2016, 07:52:26 PM »
@TimW
"The arming plug is there to be pulled any time that someone won't have the airplane adequately restrained. "
@PGermann  "Arming plugs sometimes used in Control Line model airplanes are, when being pulled while the motor runs full RPM, disconnecting the battery from the ESC. My question is whether such sudden disconnect could possibly damage the ESC?"

As I understand the rules, the AMA insisted on adding the arming plug to prevent the motor from unexpectedly starting due to a ESC or other control failure when it was unattended or not being adequately restrained.  It was never intended to be used to stop a motor while it is running.  I find it hard to see a situation where, especially with a speed model, the model is spinning around on the ground at full power and someone tries to stop it and pull a plug on it.  That would most likely make a bad situation even worse.

The only "safety" use for an arming plug is to disconnect the battery so the power plant can't accidentally start, essentially "pulling the fuel line" or "emptying the tank" on an engine powered model.  Even glow or diesel engines have been known to start simply from flipping the prop or tweaking the spinner.  That too can be a dangerous situation, especially if there is fuel in the tank or fuel line and someone is not properly restraining the model.
phil Cartier

Offline Tim Wescott

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Re: Arming Plug causing ESC damage?
« Reply #23 on: March 02, 2016, 09:28:40 PM »
@TimW
"The arming plug is there to be pulled any time that someone won't have the airplane adequately restrained. "
@PGermann  "Arming plugs sometimes used in Control Line model airplanes are, when being pulled while the motor runs full RPM, disconnecting the battery from the ESC. My question is whether such sudden disconnect could possibly damage the ESC?"

As I understand the rules, the AMA insisted on adding the arming plug to prevent the motor from unexpectedly starting due to a ESC or other control failure when it was unattended or not being adequately restrained.  It was never intended to be used to stop a motor while it is running.  I find it hard to see a situation where, especially with a speed model, the model is spinning around on the ground at full power and someone tries to stop it and pull a plug on it.  That would most likely make a bad situation even worse.

The only "safety" use for an arming plug is to disconnect the battery so the power plant can't accidentally start, essentially "pulling the fuel line" or "emptying the tank" on an engine powered model.  Even glow or diesel engines have been known to start simply from flipping the prop or tweaking the spinner.  That too can be a dangerous situation, especially if there is fuel in the tank or fuel line and someone is not properly restraining the model.

Just to clarify: by "be pulled" I meant that the plug is there to be pulled before a plane is left unrestrained -- certainly not that it's there so that one can yank it while the motor is running.

I can't think of a situation where pulling the plug on a running motor would enhance the safety of competitors and/or spectators more than it would endanger the guy reaching his hand toward a severely misbehaving electric motor with a nice sharp prop on it.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Brett Buck

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Re: Arming Plug causing ESC damage?
« Reply #24 on: March 02, 2016, 11:01:00 PM »
@TimW
"The arming plug is there to be pulled any time that someone won't have the airplane adequately restrained. "
@PGermann  "Arming plugs sometimes used in Control Line model airplanes are, when being pulled while the motor runs full RPM, disconnecting the battery from the ESC. My question is whether such sudden disconnect could possibly damage the ESC?"

As I understand the rules, the AMA insisted on adding the arming plug to prevent the motor from unexpectedly starting due to a ESC or other control failure when it was unattended or not being adequately restrained.  It was never intended to be used to stop a motor while it is running.  I find it hard to see a situation where, especially with a speed model, the model is spinning around on the ground at full power and someone tries to stop it and pull a plug on it.  That would most likely make a bad situation even worse.

The only "safety" use for an arming plug is to disconnect the battery so the power plant can't accidentally start, essentially "pulling the fuel line" or "emptying the tank" on an engine powered model.  Even glow or diesel engines have been known to start simply from flipping the prop or tweaking the spinner.  That too can be a dangerous situation, especially if there is fuel in the tank or fuel line and someone is not properly restraining the model.

  The AMA did not insist on this, I proposed it and it was passed. But it was already common to nearly universal anyway.

    The rest of it is exactly right. To need to pull the plug when it is running, one would have to have an unplanned start, have the airplane restrained or recaptured somehow, and then the person holding it not be able to stop it with the regular start switch (which takes one touch). The idea was to prevent it from starting unexpectedly in the first place.

    If you have to pull the plug with it running, you are several mistakes or accidents in already, so blowing the controller is a minor issue. It was certainly never intended to be used that way in any normal circumstances.

    Brett

Offline Howard Rush

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Re: Arming Plug causing ESC damage?
« Reply #25 on: March 03, 2016, 09:50:47 PM »
so my recomendation - do not use safety plug for regular cutting motor off, it is safety plug for emergency when cost of ESC is not an issue, not cut off plug ... in normal situation, remove it only when motor does not run ... that is why I recommend to have normal low voltage switch on ESC like you can see on Spins 66, or timer with cut off function

As I recall, the Spin 66 switch function is disabled after the motor starts.  This makes the system more reliable: a switch failing open during an overhead eight will not stop the motor.  However, The only way to stop a running motor is to pull the plug.  One could use a double-pole switch, using the other pole to short the timer output to the Spin.
The Jive Combat Team
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Offline Igor Burger

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Re: Arming Plug causing ESC damage?
« Reply #26 on: March 04, 2016, 01:30:15 AM »
Switch on Jeti spin cuts 5V to timer, not to ESC itself. So when you switch it off ruring run, I will run second or 2 and then stops like with "lost signal" from R/C, means it will not break, simply zero power.

Offline Howard Rush

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Re: Arming Plug causing ESC damage?
« Reply #27 on: March 04, 2016, 03:19:13 AM »
Thanks, Igor.  Perhaps what I saw was the effect of the large capacitor in the TUT, which is the timer in control when my motor starts. 
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Offline Igor Burger

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Re: Arming Plug causing ESC damage?
« Reply #28 on: March 04, 2016, 03:39:21 AM »
Hard to say, but with only my timer in ESC it also runs 1 or 2 sec after switching off.

Offline Tim Wescott

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Re: Arming Plug causing ESC damage?
« Reply #29 on: March 04, 2016, 10:03:55 AM »
That "large capacitor" only holds enough charge to keep the TUT running for a few milliseconds at most.  It's there to smooth out the power to the tut if you have long cables or if there's momentary power interruptions.

The signal to an ESC is a pulse; shorting the ESC signal wouldn't generate low throttle pulses.  If an ESC with a microprocessor in it* turns off in response to it's pulse train ceasing then it does so because someone made it that way.

* AFAIK, all brushless ESCs have microprocessors in them, and probably all but the oldest and cheapest brushed ESCs.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Fredvon4

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Re: Arming Plug causing ESC damage?
« Reply #30 on: March 04, 2016, 12:37:57 PM »
I don't know why I can't let this go and I apologize because I recognize many here as professional stunt fliers now using electric and I don't even fly stunt other than for fun

Perhaps I do not understand the safety Failure mode the ARMING plug is supposed to prevent

Knowing it is stunt and Control line leads me to believe the ONLY safety failure mode is a UN-COMMANDED motor/prop spin up on an other wise unrestrained aircraft

If this is false assumption then the rest is just clutter

ON a three wire Brush-less electric motor any two wires provide current to spin the motor and the third wire is feedback to the ESC/governor/Timer...but because the way they are wired there is NO specific color code ....IE any two can cause CCW spin and reversing them causes CW spin.. in each case the un specified third wire sends pulse signals down stream to the (controller)

The OP asked about removing the ARMING plug during motor running and if the resultant NOW a GENERATOR would over load the Controlling electronics and blow a component and the answer seems logically to be YES because none of the components were designed to accept this high current voltage

MY immediate thought was this is easy but not as light a fix... simply make the ARMING plug interrupt TWO motor wires AFTER the ESC

I suspect you are trying to tell me that an powered UP ESC/TIMER/Governor...demands to see some complete circuit to the MOTOR or they misbehave or fail to simply turn on....
SO///The interrupter(ARMING PLUG) to the motor needs a low current/HIGH OHM SHUNT

BTW way guys ----it is perfectly OK to tell me to go away and shut up

I acknowledge that I don't fully understand the safety and politics of this ....just trying to understand for my own curisity
"A good scare teaches more than good advice"

Fred von Gortler IV

Offline Tim Wescott

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Re: Arming Plug causing ESC damage?
« Reply #31 on: March 04, 2016, 12:57:00 PM »
I don't know why I can't let this go and I apologize because I recognize many here as professional stunt fliers now using electric and I don't even fly stunt other than for fun

Perhaps I do not understand the safety Failure mode the ARMING plug is supposed to prevent

Knowing it is stunt and Control line leads me to believe the ONLY safety failure mode is a UN-COMMANDED motor/prop spin up on an other wise unrestrained aircraft

If this is false assumption then the rest is just clutter

This is the only failure mode that the rule is intended to address.  I can dream up other failure modes (most of them involving the plane bouncing off of the ground, or bird strikes), but these are (A) rare, (B) nearly always blow the electronics immediately anyway, and (C) of the residual, most scenarios involve the entire audience either running for cover or laughing.  I really think that it's pointless to dwell on these "other scenarios".

ON a three wire Brush-less electric motor any two wires provide current to spin the motor and the third wire is feedback to the ESC/governor/Timer...but because the way they are wired there is NO specific color code ....IE any two can cause CCW spin and reversing them causes CW spin.. in each case the un specified third wire sends pulse signals down stream to the (controller)

The OP asked about removing the ARMING plug during motor running and if the resultant NOW a GENERATOR would over load the Controlling electronics and blow a component and the answer seems logically to be YES because none of the components were designed to accept this high current voltage

MY immediate thought was this is easy but not as light a fix... simply make the ARMING plug interrupt TWO motor wires AFTER the ESC

I suspect you are trying to tell me that an powered UP ESC/TIMER/Governor...demands to see some complete circuit to the MOTOR or they misbehave or fail to simply turn on....
SO///The interrupter(ARMING PLUG) to the motor needs a low current/HIGH OHM SHUNT

BTW way guys ----it is perfectly OK to tell me to go away and shut up

I acknowledge that I don't fully understand the safety and politics of this ....just trying to understand for my own curisity

OK.  I don't fly electric CL either, but I do design brushless motor drive circuits.  ANY interruption in the high-current wires are going to cause completely random high-voltage events, in no small part because when there's inductors involved (like motor coils), the current WILL find a way to complete the circuit, generally by sparking across the open switches if they can't do it some other way.  Randomly opening switches in high-current circuits like this causes a phenomenon known among experienced designers as Bad Weird S**t.  I'll call it BWS for short.

So, you won't get the same BWS by putting your arming plug in the motor lead, but you'll still get BWS.  Also, the rule as it stands is unequivocal: disconnect the battery when no one is touching the plane or handle.  Period.  Since there's folks out there that are just born to circumvent rules no matter how sensible they may be or the ease with which one can come into compliance, I don't think we want to clutter up the rules with opportunities for circumvention to solve a non-problem with an option that won't help.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Fredvon4

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Re: Arming Plug causing ESC damage?
« Reply #32 on: March 04, 2016, 01:12:01 PM »
Tim

OK brother I am going to leave it alone

But you should know...I am KD5NCO and have been building home brew circuits for decades now and understand BWS especially in 1500Watt+ (loafing) RF power amplifiers

And freely admit I shy away for micro circuitry ....because many of my efforts are power levels that require air gaps larger than the nanometer width connecting runs that include circuit board inductor and capacitors in the design of the three, four, and six layer boards....I am a HF guy with no desire to play in the micro millimeter world

73s
"A good scare teaches more than good advice"

Fred von Gortler IV

Offline Tim Wescott

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Re: Arming Plug causing ESC damage?
« Reply #33 on: March 04, 2016, 01:40:50 PM »
So would you pull the antenna lead off of a 1.5kW amplifier that's running key-down?
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Fredvon4

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Re: Arming Plug causing ESC damage?
« Reply #34 on: March 05, 2016, 07:00:48 AM »
Only if I needed to see how much smoke was really inside.... %^

BUT point taken

Thanks for putting up with my encroachment
"A good scare teaches more than good advice"

Fred von Gortler IV

Offline Brett Buck

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Re: Arming Plug causing ESC damage?
« Reply #35 on: March 05, 2016, 06:12:30 PM »
I don't know why I can't let this go and I apologize because I recognize many here as professional stunt fliers now using electric and I don't even fly stunt other than for fun

Perhaps I do not understand the safety Failure mode the ARMING plug is supposed to prevent

Knowing it is stunt and Control line leads me to believe the ONLY safety failure mode is a UN-COMMANDED motor/prop spin up on an other wise unrestrained aircraft

   That's correct, either from inadvertent button-pushing or low-level uncommanded state change. Before anyone says that's not a sensible reason, be advised that this has already happened at least 10 times to various people in a wide array of variations. And that is just to my knowledge ,there are undoubtedly more.

     Pulling the plug on a running motor is not the use case and it's hard to even envision a situation where that is likely to happen. If you can get to the plug, you can get to the start button.
   
  Brett

Offline Dick Pacini

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Re: Arming Plug causing ESC damage?
« Reply #36 on: March 06, 2016, 02:10:02 PM »
Paul;
you don't really want to do that (rag in the prop) with electric power. With glo/diesel or spark motors, yes, it works great.

Carl


Back in '75, I was practicing for the NATS and my plane had a fat run.  I set it down (trike gear) and yelled to my buddy to rag the prop when it came around.  He did as instructed and tossed a red shop towel into the prop as the plane went by.

Instantly, the entire nose broke off as well as the prop.  It lay there in a screaming shaft run for a few seconds before the OS Max 35 seized up.  Yep, it worked great...
AMA 62221

Once, twice, three times a lady.  Four times and she does it for a living.

Online Peter Germann

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Re: Arming Plug causing ESC damage?
« Reply #37 on: March 07, 2016, 04:04:00 AM »
Dear friends

with your much appreciated expert comments considered, I have today submitted the following to chairman Peter Halman of the FAI F2  Control Line Subcommittee:

Quote:

Regarding the risk of unintentional motor start, I would  like to suggest the following amendments of ABR 1.3.2

c.) Electric powered control line model aircraft with their battery (-ies) connected to the speed controller (-s) and the motor (-s) connected to the speed controller (-s) must be restrained at all times except during take-off, flight and landing operations.

Reason, not to be part of the amendment:
When being connected as described the speed controller (-s) of an electric power train may at any time start the motor (-s) on its (their) own. Therefore, with batteries connected, restraining the aircraft is the primary measure for safe operations.

d.) Electric powered control line model aircraft must be equipped with suitable devices to cut the flow of power from the battery (-ies) to the speed controller (-s) or from the speed controller (-s) to the motor (-s). Such devices must be easy accessible, without the use of tools.

Reason, not to be part of the amendment:
Even when restraining the aircraft as per c.), unintentional motor start on ground remains to be a critical safety hazard. Also, depending of the type of malfunction in the esc, depressing the “Start” button again for shut-off may not work. Therefore, the easy accessibility of systems and/or devices allowing to cut the flow of power serves as subsidiary safety measure. Such systems/devices could be an arming plug installed in the primary circuit between battery and speed controller, easy accessible battery connectors, or a 2-leads arming plug installed in the secondary circuit between esc and motor.

End of quote.

Thank you for contributing,I will keep you informed.

Peter Germann

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Offline Tim Wescott

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Re: Arming Plug causing ESC damage?
« Reply #38 on: March 07, 2016, 10:21:39 AM »
Hey Peter:

Just a comment, I'll leave the proposed rule to your judgment:

I could see fights breaking out over the interpretation of "suitable devices".  This is why Brett's rule specifically calls out complete mechanical disconnection (with "switch" implied, but that could be put in explicitly) -- that saves you from someone who wants to have an electronic cut-off device that's subject to all the same limitations as an ESC/timer combo.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Wolfgang Nieuwkamp

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Re: Arming Plug causing ESC damage?
« Reply #39 on: March 07, 2016, 11:15:58 AM »
Hello Peter,

Tim´s comment is correct. The last sentence could read "Such devices must provide a contact separation of at least 0,5 mm, and be easily accessible without the use of tools"

Regards,

Wolfgang

Offline Brett Buck

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Re: Arming Plug causing ESC damage?
« Reply #40 on: March 12, 2016, 06:53:03 PM »
Hey Peter:

Just a comment, I'll leave the proposed rule to your judgment:

I could see fights breaking out over the interpretation of "suitable devices".  This is why Brett's rule specifically calls out complete mechanical disconnection (with "switch" implied, but that could be put in explicitly) -- that saves you from someone who wants to have an electronic cut-off device that's subject to all the same limitations as an ESC/timer combo.

    I explicitly stated "mechanical" to preclude transistor switches/SCRs, etc. which would be tempting solutions due to the weight saving. The sort of switch you would need for any sort of reliable operation is very heavy

     Brett

Offline Tim Wescott

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Re: Arming Plug causing ESC damage?
« Reply #41 on: March 12, 2016, 07:00:22 PM »
The sort of switch you would need for any sort of reliable operation is very heavy.

I think a knife switch could be made nearly as light as an arming plug.  But that's splitting hairs -- there's nothing out there to just buy.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Online Peter Germann

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Re: Arming Plug causing ESC damage?
« Reply #42 on: March 14, 2016, 05:26:14 AM »
The last sentence could read "Such devices must provide a contact separation of at least 0,5 mm, and be easily accessible without the use of tools"
Wolfgang

How about this:

d.) Electric powered control line model aircraft must be equipped with mechanical contact separation devices to cut the flow of power from the battery (-ies) to the speed controller (-s) or from the speed controller (-s) to the motor (-s). Such devices must be easily accessible, without the use of tools.

rgds. Peter
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Offline Brett Buck

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Re: Arming Plug causing ESC damage?
« Reply #43 on: March 14, 2016, 09:35:15 AM »
How about this:

d.) Electric powered control line model aircraft must be equipped with mechanical contact separation devices to cut the flow of power from the battery (-ies) to the speed controller (-s) or from the speed controller (-s) to the motor (-s). Such devices must be easily accessible, without the use of tools.

rgds. Peter

   I am still not sure what situation you are concerned with with regard to pulling the plug with it running. If you can hold  it well enough to pull the plug, you should be able to push the button, or just let it run and take your chances.

   The original rule intentionally permitted someone to just use the battery plug for the same purpose. One could just wait until they were ready to go, plug in the battery, pop on the cowl (however it is fastened) and then go - as long as someone had a good hold on it. This permitted you to save the weight of the plug and socket if you were willing to put up with the inconvenience of putting the cowl on in the circle.

      The only thing I can think you are saving with this rule is some sort of electronic failure, where pushing the button fails to stop a runaway (that is otherwise restrained and safe). It seems to me that this is a builder decision - take the chance of burning up some electronic that have already failed in some way VS damaging the same electronics by pulling the plug from back EMF.  It doesn't help the problem I was originally trying to address (unrestrained runaways) at all, because it has to be restrained in order to pull the plug, too.

   Could you maybe explain what you are trying to protect against with this aspect of the change?

     Brett

Online Peter Germann

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Re: Arming Plug causing ESC damage?
« Reply #44 on: March 14, 2016, 10:08:16 AM »
 Could you maybe explain what you are trying to protect against with this aspect of the change?
 Brett

I believe the essential part of the rule is the restraining of the airplane at all times when the battery is connected. In case a helper carring the acft back to the pits after landing cannot reach the stop button when an unintional restart occurs, or when pressing the stop button does not work, disconnecting as suggested in 1.3.2.d.) could well be the only effective measure to prevent damage from extended static runs at full speed. The method of disconnceting is, apart from the possible esc damage risk, not really important. What is important is that the method is effective and easily feasible.

Or, if I may put it the other way around, I think we need both, restraining airplanes with hot power trains and easily accessible ("mechanical") circuit brakers.

Peter
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Offline Tim Wescott

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Re: Arming Plug causing ESC damage?
« Reply #45 on: March 14, 2016, 10:54:08 AM »
How about this:

d.) Electric powered control line model aircraft must be equipped with mechanical contact separation devices to cut the flow of power from the battery (-ies) to the speed controller (-s) or from the speed controller (-s) to the motor (-s). Such devices must be easily accessible, without the use of tools.

rgds. Peter

That wording sounds good to me.  Of course, I don't fly in any FAI competitions, so take what I say as a suggestion only.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Brett Buck

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Re: Arming Plug causing ESC damage?
« Reply #46 on: March 14, 2016, 11:53:30 AM »
I believe the essential part of the rule is the restraining of the airplane at all times when the battery is connected. In case a helper carring the acft back to the pits after landing cannot reach the stop button when an unintional restart occurs, or when pressing the stop button does not work, disconnecting as suggested in 1.3.2.d.) could well be the only effective measure to prevent damage from extended static runs at full speed. The method of disconnceting is, apart from the possible esc damage risk, not really important. What is important is that the method is effective and easily feasible.

Or, if I may put it the other way around, I think we need both, restraining airplanes with hot power trains and easily accessible ("mechanical") circuit brakers.

    I see. But I don't see how it improves safety consequentially - it might, in extreme circumstances, save the battery, but it doesn't appear to have much effect on personnel safety.

    I don't particularly object to this as a practice (and mine will certainly have a conventional arming plug like everybody else uses) but I would be more inclined to leave it out of the rulebook as a mandatory item.

    Brett

Online Peter Germann

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Re: Arming Plug causing ESC damage?
« Reply #47 on: March 15, 2016, 03:51:41 AM »
The suggested amendment shall be made to rule 1.3.2 in Volume ABR which means that it will be binding not for F2B (stunt)alone but for all classes of the control line category in FAI. In F2G (electric speed), for example, power is typically controlled by r/c and the installation of a circuit braker is planned to become mandatory. As further classes may well be electrified in future, such as F2D (combat), the terms of ABR 1.3.2. shall be written to best possibly take into account the (future) safety requirements of all c/l classes.
Peter Germann

Offline Brett Buck

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Re: Arming Plug causing ESC damage?
« Reply #48 on: March 15, 2016, 11:47:00 AM »
The suggested amendment shall be made to rule 1.3.2 in Volume ABR which means that it will be binding not for F2B (stunt)alone but for all classes of the control line category in FAI. In F2G (electric speed), for example, power is typically controlled by r/c and the installation of a circuit braker is planned to become mandatory. As further classes may well be electrified in future, such as F2D (combat), the terms of ABR 1.3.2. shall be written to best possibly take into account the (future) safety requirements of all c/l classes.

  Circuit breaker? Where did that come from?  If anything, I would not include a circuit breaker, but a fusible link, but I don't think you need either.

   Again, I am not sure why the second part is wise to make mandatory. Rules should be implemented to improve personnel safety when necessary, but not to protect equipment from the owners decisions (like, I don't want the weight of an arming plug and will take my chances on a restrained runaway).

    Brett

Online Peter Germann

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Re: Arming Plug causing ESC damage?
« Reply #49 on: March 16, 2016, 08:50:54 AM »
  Circuit breaker? Where did that come from?  If anything, I would not include a circuit breaker, but a fusible link, but I don't think you need either.
Again, I am not sure why the second part is wise to make mandatory. Rules should be implemented to improve personnel safety when necessary, but not to protect equipment from the owners decisions (like, I don't want the weight of an arming plug and will take my chances on a restrained runaway).
Brett

Sorry for the misuse of "circuit breaker." What I meant was a device mechanically separating the power from the esc or form the motor. Which could be an arming plug or the unplugging of one of power leads, provided the plug can be reached easily w/o the use of tools. Such as in case of a top loader with a snap-on battery compartment cover or in case a profile fuselage.
Peter
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