EMI/RFI Dangerous?

[Pota]

I have made a gokart. Rather powerfull i would say.
It weights around 160-165kg.
700amp and 180volt.

And I have recently been thinking about the EMI/RFI. How dangerous is it to sit so close to such much current rushing trough to the motor siting right behind me?

Best Regards

Thomas

 

[Punx0r]

Unless you have a pacemaker, not at all :wink:

 

[Drunkskunk]

I have made a gokart. ...
700amp and 180volt.
..... How dangerous is it to sit so close to such much current rushing trough to the motor siting right behind me? ...

Deadly, if you're as crazy as me. Seriously, that ought to be fun. There is something very special about building a machine so overpowered that you get that quiet moment of reflection before your first ride, knowing that may have built the thing that kills you. it's a rush few people get to share.
But none of that risk comes from EMI/RFI/EMF/EMP. While high EMF has a known vector for concern in small children, no causal link has ever been found. there is no vector of concern for older children or adults.

In English, that means scientists think it might be possible that small children are at risk for some bad health effects, but no case has ever been found where it actually did cause any harm. And they know it don't do shit to bigger kids or adults.

Seriously, you got RF radiation passing through you all the time. Lots of it. F'ing scary amounts of it from sources all over the place. where ever you are sitting right now, there are probably 100,000 cell phones with signals strong enough to read the data from. as long as they are on, they are transmitting in all directions, and those go right through your body. And Cellphones are a drop in the bucket. Everything is wifi enabled now days, all of that is broadcasting, and those signals go much further out than they can reliably connect with. Then you have all the blue tooth devices, and RF wireless mice, keyboards, garage door openers. All the radio channels, and all the TV channels with powerful antenna broadcasting their powerful signals all the time, right through you. Satellite radio and TV? it's being broadcast right through you from above, with multiple satellites broadcasting down on you at any given time. Weather radar, air traffic radar, national defense radar? always on, always bouncing through you, some times both directions.

And we're still just scratching the surface of electromagnetic radiation. Power lines, electric motors, microwave ovens, street lights, house wiring. it's enough to make some people wear a tinfoil hat!
But it really is safe. We as a life form evolved in an environment that's being bombarded by massive amounts of EMR all the time. The sun has been blasting away at the earth with a massive and constant stream, and sometimes epic bursts of EMR since the earth was a little dust cloud hoping to grow up into a ball of mud. And for all that, it ain't hurt no one yet.

 

[billvon]

But none of that risk comes from EMI/RFI/EMF/EMP. While high EMF has a known vector for concern in small children, no causal link has ever been found. there is no vector of concern for older children or adults.

In English, that means scientists think it might be possible that small children are at risk for some bad health effects, but no case has ever been found where it actually did cause any harm. And they know it don't do shit to bigger kids or adults.

Nope. No known issues in kids _or_ adults.

Seriously, you got RF radiation passing through you all the time. Lots of it. F'ing scary amounts of it from sources all over the place. where ever you are sitting right now, there are probably 100,000 cell phones with signals strong enough to read the data from. as long as they are on, they are transmitting in all directions, and those go right through your body. And Cellphones are a drop in the bucket.

Everything is a drop in the bucket compared to the sun.

The most powerful cellphone out there might put a watt of non-ionizing radiation into your body. Non-ionizing means it does not break molecular bonds in things like proteins and DNA. A huge amount of it can warm you up (think microwaves) but other than that doesn't cause damage.

Just stepping into the sun exposes you to a few hundred watts of _ionizing_ radiation - the sort of radiation that will break molecular bonds in DNA and give you skin cancer.

 

[Pota]

I have made a gokart. ...
700amp and 180volt.
..... How dangerous is it to sit so close to such much current rushing trough to the motor siting right behind me? ...

Deadly, if you're as crazy as me. Seriously, that ought to be fun. There is something very special about building a machine so overpowered that you get that quiet moment of reflection before your first ride, knowing that may have built the thing that kills you. it's a rush few people get to share.
But none of that risk comes from EMI/RFI/EMF/EMP. While high EMF has a known vector for concern in small children, no causal link has ever been found. there is no vector of concern for older children or adults.

In English, that means scientists think it might be possible that small children are at risk for some bad health effects, but no case has ever been found where it actually did cause any harm. And they know it don't do shit to bigger kids or adults.

Seriously, you got RF radiation passing through you all the time. Lots of it. F'ing scary amounts of it from sources all over the place. where ever you are sitting right now, there are probably 100,000 cell phones with signals strong enough to read the data from. as long as they are on, they are transmitting in all directions, and those go right through your body. And Cellphones are a drop in the bucket. Everything is wifi enabled now days, all of that is broadcasting, and those signals go much further out than they can reliably connect with. Then you have all the blue tooth devices, and RF wireless mice, keyboards, garage door openers. All the radio channels, and all the TV channels with powerful antenna broadcasting their powerful signals all the time, right through you. Satellite radio and TV? it's being broadcast right through you from above, with multiple satellites broadcasting down on you at any given time. Weather radar, air traffic radar, national defense radar? always on, always bouncing through you, some times both directions.

And we're still just scratching the surface of electromagnetic radiation. Power lines, electric motors, microwave ovens, street lights, house wiring. it's enough to make some people wear a tinfoil hat!
But it really is safe. We as a life form evolved in an environment that's being bombarded by massive amounts of EMR all the time. The sun has been blasting away at the earth with a massive and constant stream, and sometimes epic bursts of EMR since the earth was a little dust cloud hoping to grow up into a ball of mud. And for all that, it ain't hurt no one yet.

Very good and informativ posts!

What if.. I told you... i have medical device such as pacemaker or other devices on my body. Would the sun etc give med more EMI/RFI/EMF/EMP radiaton than my gokart?

 

[dustNbone]

If you've ever rode an electric train (diesel electric included), taken a high speed elevator, walked under high tension transmission lines, had an x-ray, etc. then you've probably already done much worse than a little go kart will.

 

[billvon]

What if.. I told you... i have medical device such as pacemaker or other devices on my body. Would the sun etc give med more EMI/RFI/EMF/EMP radiaton than my gokart?

The sun gives you more damaging radiation than anything else by orders of magnitude. (Unless you live in Chernobyl or something . . . )

For the rest of it:

EMI stands for electromagnetic interference. It's what makes your radio stop working when you are near an electric motor. It's a problem for other devices, but is so small in terms of energy that it's not worth worrying about in terms of exposure.

RFI stands for radio frequency intereference. Usually the same as EMI, except EMI is broader-band.

EMF stands for either electromotive force or electromagnetic fields. Probably the latter based on usage. The strength of these is often given in units of electrical or magnetic field. Note that it is generally referring to _static_ fields, fields that either aren't moving or are moving so slowly that they are effectively static. Power line coupling is an example; 60Hz is very slow. However, the biggest EMF you are exposed to cumulatively over the course of your life is the Earth's magnetic field. Not because it's very strong but because it's always there.

EMP is an electromagnetic pulse, caused by transient events like lightning, arc faults in power lines or nuclear weapons. If you are near any of those things, you have a lot more to worry about than exposure to a transient EM field!

 

[ckelly78z]

Unless you have a pacemaker, not at all :wink:

Lats year, due to heart failure brought on by past chemotherapy drugs, I got a new pacemaker. No more welding, or standing over running engine alternators. I imagine that a high powered gocart might also qualify for the list.

 

[madin88]

EMF stands for either electromotive force or electromagnetic fields. Probably the latter based on usage. The strength of these is often given in units of electrical or magnetic field. Note that it is generally referring to _static_ fields, fields that either aren't moving or are moving so slowly that they are effectively static. Power line coupling is an example; 60Hz is very slow. However, the biggest EMF you are exposed to cumulatively over the course of your life is the Earth's magnetic field. Not because it's very strong but because it's always there.

Static magnetic fields should not make any problems at least thats how it is for electronic devices.
A magnetic field coming from 700A which is alternating at motor ERPM and controller PWM is a whole different case and could be way more "dangerous".
If you have a given frequency and given length of wire, the wire could act like an antenna and emit a signal (with lot of energy in it). So it depends on many factors.
What you could do to reduce the emissions is using shilded wires for the phases and twisting them. Those orange colored EV cables are normally shilded so i would use them. Routing all the wires through a metal tube will also reduce noise.

 

[Punx0r]

I don't think the orange EV cable is shielded?

Bits of an EV power train might kick out some serious low frequency electrico-magentic noise that might mess up other electrical equipment but us bags of biology are pretty darn immune to it. Even something like a ship's radar which emits around 50kW of microwave EMF (higher frequency = more worse) is no hazard to people unless you get up extremely close (or stare into the emitter), in which case it will start to simply warm up your skin. Once you're 10m/30ft away the itensity is only 1/10th of the maximum safe exposure.

But yeah, your wifi or phone is unlikely to work and if you've got a medical electronic implant you'll be staying well, well away.

 

[Drunkskunk]

Well that changes things a bit. EMI, RFI, EMF, EMP, EMR, etc, etc are all Safe for organic life. They may not be safe for sensitive electronic life. If you've become 0.1% cyborg, and had some device implanted in you like a pace maker, you're dealing with a whole different problem.

Many pacemakers are built with a sensitive magnetic switch. if you place a magnet near them, they switch modes. Some go into diagnostic mode, where a DR with an EKG hooked up to you can read the battery life and other diagnostic data. Others will switch off so the Dr can tell how well your heart is doing on it's own. Some will do both, depending on how the magnet is placed, or the number of times it's placed. They are also sensitive to electronic noise from anything that can transmit.

Taken from The Boston Scientific:

Safe to Use Normally
These household items are generally safe to use with a pacemaker as long as they are in good working condition and used as intended:

Air purifiers
Blenders
CD/DVD Players
Clothes washing machines
Electric blankets
Electric can openers
Electric invisible fences
Electric toothbrushes
Fax/copy machines
Hair dryers
Heating pads
Hot tubs/whirlpool baths
NOTE: Talk with your doctor before using a hot tub. It will not harm your pacemaker but hot tubs may affect your medical condition.
Laser tag games
Microwave ovens
Ovens (electric, convection, or gas)

Pagers
Patient alert devices
Personal computers
Personal digital assistants (PDAs)
NOTE: PDAs that are also cell phones should be kept at least 6 inches away from your pacemaker.
Portable space heaters
Radios (AM and FM)
Remote controls (TV, garage door, stereo, camera/video equipment)
Stoves (electric or gas)
Tanning beds
Televisions
TV or radio towers (safe outside of restricted areas)
Vacuum cleaners
VCRs
Video games


Safe to Use at a Distance

It is safe to use these items so long as you don’t place them directly over your pacemaker:

Cordless (household) telephones
Electric razors
Hand-held massagers
Portable MP3 and multimedia players (such as iPods®) that do not also function as a cellular phone
NOTE: While portable MP3 players should not interfere with your pacemaker, the headphones or earbuds should be stored at least 6 inches (15 cm) away from your pacemaker. You should avoid draping the headphones around your neck.



Keep at least 6 inches (15 cm) away from your pacemaker:

Cellular phones, including PDAs and portable MP3 players with integrated cellular phones
Devices transmitting Bluetooth® or Wi-Fi signals (cell phones, wireless Internet routers, etc.)
Headphones and earbuds
NOTE: It’s safe to use headphones and earbuds. But you should not drape them around your neck or store them in a breast or other shirt pocket.
Magnetic wands used in the game of Bingo

Keep at least 12 inches (30 cm) away from your pacemaker:

Battery-powered cordless power tools
Chainsaws
Corded drills and power tools
Lawn mowers
Leaf blowers
Remote controls with antennas
Shop tools (drills, table saws, etc.)
Slot machines
Snow blowers
Stereo speakers

Keep at least 24 inches (60 cm) away from your pacemaker:

Arc welders
CB and police radio antennas
Running motors and alternators, especially those in vehicles
NOTE: Avoid leaning over running motors and alternators of a running vehicle. Alternators create large magnetic fields that can affect your pacemaker. However, when you are driving or riding you are at a safe distance.

Using Cell Phones Safely

Your cell phone is a source of EMI and could affect your pacemaker temporarily. Once you move the phone away from your pacemaker, it will return it to working as usual.

Keep at least 6 inches (15 cm) between the cell phone and your pacemaker. If the phone transmits more than 3 watts, keep the phone 12 inches (30 cm) away.
Hold the phone to your ear on the opposite side of your body from your pacemaker.
Do not carry a cell phone in a breast pocket or on your belt if that places the phone within 6 inches (15 cm) of your pacemaker.

This applies only to cell phones, not to household cordless phones. But you should avoid placing your household cordless phone receiver directly over your pacemaker.

NOT Safe for Use

These items are not safe to use if you have a pacemaker:

Body-fat measuring scales
Jackhammers
Magnetic mattresses and chairs
Stun guns

Source: http://www.bostonscientific.com/con...ker/using-household-appliances-and-tools.html

 

[billvon]

What you could do to reduce the emissions is using shilded wires for the phases and twisting them. Those orange colored EV cables are normally shilded so i would use them. Routing all the wires through a metal tube will also reduce noise.

Also add capacitance. That will cut down on higher frequency EMI (and induced currents increase with frequency.)

 

[Stevew77]

You can put shielding ( like alu foil ) between you and the cables and motors, but worth putting a trailing earth strap onto the cart so any static build up or induced voltage from the electric field from cables or motors, discharges to ground.

 

[Ralyant]

I need to see this gokart!

Im wanting to build an electric gokart also!