How an EMC problem can kill people and a company

[b_force]

Yes EMC is very likely.
Although it has been many years, i actually worked on a project for a company dealing with these high voltage lines for trains.
The EMC introduces quite some issues. For that reason every conducting object has to be grounded around railway tracks.
You can actually see this, since the wires are bolted on fences, benches and such.

But in the end it's not a software or EMC fault.
It's lack of a decent backup system if everything fails.
Such a unit needs a mandatory easy to access kill button and brakes for these kind of situations.
Pretty much like a kill button on (heavy) equipment.

I guess our rules and regulations aren't that far yet unfortunately.

[Mr. Scram]

Yes EMC is very likely.
Although it has been many years, i actually worked on a project for a company dealing with these high voltage lines for trains.
The EMC introduces quite some issues. For that reason every conducting object has to be grounded around railway tracks.
You can actually see this, since the wires are bolted on fences, benches and such.

But in the end it's not a software or EMC fault.
It's lack of a decent backup system if everything fails.
Such a unit needs a mandatory easy to access kill button and brakes for these kind of situations.
Pretty much like a kill button on (heavy) equipment.

I guess our rules and regulations aren't that far yet unfortunately.

People keep speaking of kill buttons, but electric cars don't have those and electric bicycles don't have either.

[lamello]

I am stunned by the fact that this stint has several primal DESIGN faults.

1) It is unacceptable that the breaks can't stop the vehikel if the motor is in full power.

2) There is on easy to reach emergency break.

Only for the first reason alone it had never been allowed on the road.










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[b_force]

Yes EMC is very likely.
Although it has been many years, i actually worked on a project for a company dealing with these high voltage lines for trains.
The EMC introduces quite some issues. For that reason every conducting object has to be grounded around railway tracks.
You can actually see this, since the wires are bolted on fences, benches and such.

But in the end it's not a software or EMC fault.
It's lack of a decent backup system if everything fails.
Such a unit needs a mandatory easy to access kill button and brakes for these kind of situations.
Pretty much like a kill button on (heavy) equipment.

I guess our rules and regulations aren't that far yet unfortunately.

People keep speaking of kill buttons, but electric cars don't have those and electric bicycles don't have either.

Sorry, I don't follow how this is an argument that explains why some kind of safety mechanism is a bad thing?

[Mr. Scram]

Sorry, I don't follow how this is an argument that explains why some kind of safety mechanism is a bad thing?

I'm merely pointing out that they're not as required as some people are purporting here. You can live without them just fine, apparently.

[b_force]

I am stunned by the fact that this stint has several primal DESIGN faults.

1) It is unacceptable that the breaks can't stop the vehikel if the motor is in full power.

2) There is on easy to reach emergency break.

Only for the first reason alone it had never been allowed on the road.










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That is exactly my point.

I am just wondering. But most of these devices are never really used on a big scale.
Mostly they are just toys
So therefore it wasn't a big deal in the past.

[nctnico]

Now I'm going to give a very unpopular opinion:
Until there are facts, instead of many articles with speculation (like here) it can very well still be possible that the operator was distracted and accidentally move the throttle and panicked.

It could be a possibility but given the fact the government has revoked the road worthiness license there is much more going on here than an operator error. Such a decission can result in a major damage claim if it turns out there are no good grounds for it. Remember there is video footage of the accident (not publicly available) so the government's investigators have been able to see exactly what the operator was doing before the crash.

Having many cargo bikes on the road without problems doesn't mean there are no problems lurking. One of my customers has a large number of devices installed in the field (tested for CE compliance). In a particular case they found out that it was being affected by an electric motor mounted nearby. As a result the design got altered so the device works in that situation. That is one out of thousands of devices which had a problem in a particular situation. My customer choose to act on it and improve the product.

Anyway: it will be interesting to see if the investigation can reveal the root cause of the accident and if so what the cause is.

[b_force]

Sorry, I don't follow how this is an argument that explains why some kind of safety mechanism is a bad thing?

I'm merely pointing out that they're not as required as some people are purporting here. You can live without them just fine, apparently.

?

Well it is clear apparently not. Otherwise those kind of accidents wouldn't happen.
Keep in mind that you have to read "kill switch" as; "something to prevents the whole system to go crazy".

[nctnico]

Sorry, I don't follow how this is an argument that explains why some kind of safety mechanism is a bad thing?

I'm merely pointing out that they're not as required as some people are purporting here. You can live without them just fine, apparently.

On normal cars the ignition key cuts the power to the ignition (or close the fuel valve on a diesel). I would like to think that these systems are designed with some safety behind them. Even with key-less entry systems the electronic/electrical system of any car would need to be tested according to automotive standards.

[Mr. Scram]

?

Well it is clear apparently not. Otherwise those kind of accidents wouldn't happen.
Keep in mind that you have to read "kill switch" as; "something to prevents the whole system to go crazy".

You can't draw that conclusion, as that would suggest the lack of kill switch is the single cause of the accident. Again, I'm merely pointing out that hundreds of thousands of electric cars and bicycles are on the road without one. That makes it hard to claim it's absolutely required. The safety of electric vehicles doesn't seem to be dependent on the presence of kill switch.

We should also be mindful not to take this accident as a representative example, not yet at least. Maybe the investigation will tell us this was bound to happen, but for now it seems hundreds of thousands of children have been transported with these vehicles and four have perished in a single accident. That in itself doesn't warrant the conclusion that these vehicles are inherently unsafe.

[Mr. Scram]

On normal cars the ignition key cuts the power to the ignition (or close the fuel valve on a diesel). I would like to think that these systems are designed with some safety behind them. Even with key-less entry systems the electronic/electrical system of any car would need to be tested according to automotive standards.

Unless I'm misunderstanding things, this vehicle has the same feature.

[lamello]

On normal cars the ignition key cuts the power to the ignition (or close the fuel valve on a diesel). I would like to think that these systems are designed with some safety behind them. Even with key-less entry systems the electronic/electrical system of any car would need to be tested according to automotive standards.

Unless I'm misunderstanding things, this vehicle has the same feature.

The ignition switch will stop the stint. There are only some issues.
1) to reach the ignition key, the driver has to release the break. The stint will accellate (more panic).
2) the driver of the stint doesn't sit, it stands. In case of an emergency the driver has to release one hand of the stick ( and keep his balance) to reach the ignition switch ( possible hesitation).





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[Berni]

I don't think it needs a big red stop button on it. Cars have keys in them and this has too. But they are getting replaced by buttons, im guessing there is some fail safe design behind those. Electric cars usually have big contractors on the battery to disconnect it (very useful in a electrical fire). In the electrical hydroplaning jetsky thing we designed the electronics for, there was a bracelet kill switch that also caused these big battery contractors to disconnect while also stopping it in software at the same time.

But i do think this should have mechanical breaks on it even if the motor is used for braking. Even if the motor is used for that then the same handlebar lever should be used to operate that function so that light pulls on it activate regenerative braking and harder pulls operate the mechanical brake calipers. That way if the regenerative braking fails the driver in panic will pull it all the way to quickly get into mechanical braking.

But yes it could even be operator error as far as we know. If it happens in cars it could happen just as well here.

[b_force]

I am not drawing conclusions but frm a technical point of view i just find it strange that there doesn't seem to be such a mechanism.

Btw. There is a reason that in a lot of countries those electric bikes without peddling assistance are illegal.
As for electric cars, i don't know.

But it the end. It's still not an argument to say other things don't have it.
In fact if we look back in history most regulations bad accidents first need to happen before changing or introducing laws and regulations.
So in this case you could also see it as a way to prevent other horrible things happening in the future.

[Kjelt]

But the thing that really underlines why they mention being incapable:
- High current cables (16A) were improperly routed, and heat could accumulate in the enclosure. This could lead to problems with the solder used that apparently melts at 72 C. While the engine has a thermal cutoff at 82C.
Anyone seen either 72 or 82 C solders? 

I thought that was weird but the following wiki states melting point starting at 90^oC

https://en.wikipedia.org/wiki/Solder

I wonder if they did not mean the melting of the plastick isolation of the wire. 

[coppercone2]

they probobly forgot a 1 or 2

a key on a bike is retarded because you might be going down a hill or on a slope or some shit and you need to balance the wheel when your hands. It needs to be non fumbly and quick. Or bumpy road.. alot harder to drive with 1 hand. Your sitting comfortably in a car, one hand has alot more power then on a bike when your using your body to balance it. Even without power steering in a car you can kinda anchor yourself into the seat and really stiffen your back to get power out of one hand, if you do that on a bike its easy to lose balance.

I would like a handle bar you slam on or something to break a faux-joint to cut power. Preferably not a button but from some kind of body  reflex. Like a torque wrench.

So you can maintain full driving position with maximum control but just do something with your hands to exert some kind of force on the steering bar to break the circuit,

[nctnico]

But the thing that really underlines why they mention being incapable:
- High current cables (16A) were improperly routed, and heat could accumulate in the enclosure. This could lead to problems with the solder used that apparently melts at 72 C. While the engine has a thermal cutoff at 82C.
Anyone seen either 72 or 82 C solders? 

I thought that was weird but the following wiki states melting point starting at 90^oC

I think someone got a few things mixed up in that text. A thermal cut-off on an electric motor has nothing to do with the wiring. Maybe a typist put it together from some hand written notes.

[Kjelt]

But the thing that really underlines why they mention being incapable:
- High current cables (16A) were improperly routed, and heat could accumulate in the enclosure. This could lead to problems with the solder used that apparently melts at 72 C. While the engine has a thermal cutoff at 82C.
Anyone seen either 72 or 82 C solders? 

I thought that was weird but the following wiki states melting point starting at 90^oC

I think someone got a few things mixed up in that text. A thermal cut-off on an electric motor has nothing to do with the wiring. Maybe a typist put it together from some hand written notes.

Pretty shocking for an official government reply, very sloppy.

[langwadt]

But the thing that really underlines why they mention being incapable:
- High current cables (16A) were improperly routed, and heat could accumulate in the enclosure. This could lead to problems with the solder used that apparently melts at 72 C. While the engine has a thermal cutoff at 82C.
Anyone seen either 72 or 82 C solders? 

I thought that was weird but the following wiki states melting point starting at 90^oC

https://en.wikipedia.org/wiki/Solder

googling says 66.3In33.7Bi is 72'C

[coppercone2]

thats way too expensive for this job

[langwadt]

thats way too expensive for this job

it also absolutely no sense to use 72'c solder except for maybe a blob in a thermal fuse

[Mr. Scram]

they probobly forgot a 1 or 2

a key on a bike is retarded because you might be going down a hill or on a slope or some shit and you need to balance the wheel when your hands. It needs to be non fumbly and quick. Or bumpy road.. alot harder to drive with 1 hand. Your sitting comfortably in a car, one hand has alot more power then on a bike when your using your body to balance it. Even without power steering in a car you can kinda anchor yourself into the seat and really stiffen your back to get power out of one hand, if you do that on a bike its easy to lose balance.

I would like a handle bar you slam on or something to break a faux-joint to cut power. Preferably not a button but from some kind of body  reflex. Like a torque wrench.

So you can maintain full driving position with maximum control but just do something with your hands to exert some kind of force on the steering bar to break the circuit,

You don't balance a bicycle at anything but near standstill with your hands, and definitely not this four wheeled vehicle. While I do think that this vehicle may benefit from a more intuitive kill switch, I'm not buying that a car's ignition switch is that much better.

[coppercone2]

you definatly adjust your body on a turn and even more so if its bumpy/gradient is changed during  turning.

have you ever lost a turn in a four wheeled vehicle (i.e. bad highway ramp going too fast when you need to correct after you already feel the lurch from being thrown into a slide?)

Most people won't keep one hand on the wheel when their vehicle is slipping. If your driving with one hand your gonna freaking jump on the wheel with the other one (though your an idiot if you drive with one hand)

same for ATV

[chris_leyson]

At level crossings you have to raise the height of the overhead lines to allow for lorries. In the UK the height of the overhead line is 5.6m at level crossings and 6.75m on a high load routes. You have to raise and then lower the overhead line at level crossings so arcing between the line and pickup is going to be more likely.

If it's a main line then 25kV is used throughout most of the World and these days a balanced 50kV autotransformer system seems to be the "gold standard" because you only need a grid tap every 75km or so but that beside the point.

From an EMC point of view you've got a 25kV AC line at a height of 5.6m for sake of argument so an arc from the line to the train would produce a vertical electric field strength of perhaps 6kV/m if the train looked like a short circuit when the line reconnected. At some frequencies you might even get a 12kV/m transient because of resonance.

What are the EMC emission standards for 25kV traction systems under transient conditions ? I've just done some "on the fly" ballpark estimations for vertical electric fields and I haven't even considered the magnetic field transients when you have potetially 50A current paths disconnecting and reconnecting.

Level crossings and electric trains, perhaps more likelihood of a transient EM event due to the "gradient" of the overhead lines and potentially some very high transient field strengths. Do automotive standards test to this sort of transient field strength ? I can't see cheap control electronics housed in a plastic enclosure as having much immunity at all so I wouldn't rule out EMC. EMC problem, just trying to keep the subject on topic because it's an engineering forum. What the hell has breaking using a petrol or deisel engine and gear box got to with anything FFS.

10V/m CW EMC immunity aint the same as 10kV/m transient. If it turns out to be EMC related then that's a lack of due diligence on behalf of the manufacturers and those who create and enforce the standards.

[rs20]

I am not drawing conclusions but frm a technical point of view i just find it strange that there doesn't seem to be such a mechanism.

Things like lathes, milling machines etc have emergency stop buttons because if something suddenly goes haywire, there is no other way to quickly remove energy from the system and ostensibly recover to a safe situation.

In a vehicle; there's already a "make everything stop right now I don't want to be moving button": the brake.

To observe a situation where the brake has failed, and to say "my goodness there clearly needs to be an emergency stop button here" is kind of weird. Approximately 0% of users would know where it is, the manual would have a hard time describing when to use it ("dear user, if the brakes fail (WTF!?), press this button"). If the driver in this incident had 5 seconds to think things through, he could have steered to a different location or done any other number of evasive maneuvers. It's just ridiculous to assert that an emergency stop button would have entered the driver's mind as an option in that fraction of a second, even if one was present.

So how about this: let's make the bloody brakes work instead of going on about "emergency stop" buttons.

In fact if we look back in history most regulations bad accidents first need to happen before changing or introducing laws and regulations.
So in this case you could also see it as a way to prevent other horrible things happening in the future.

Something needs to happen, yes. You've failed to demonstrate that an E-stop button is that solution, though.