Mark Williams
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Would this work to vary the temp. My question is what the heck to do with the ground wire. Would I wire it to the body of the oven (not shown in drawing ,will be surrounding heating element)
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Electrical question
- Thread starter Mark Williams
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I'm far from an expert, but it sounds ok to me. The heating element is based on resistance, so if you vary the voltage you should get different temperatures. I don't know about the ground.
I don't think thats how most ovens work though. I think the heating element runs at a constant voltage or current, and the thermostat turns it on and off as needed.
I don't think thats how most ovens work though. I think the heating element runs at a constant voltage or current, and the thermostat turns it on and off as needed.
Mark Williams
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No electricians huh? I do have life insurance and wont hold anyone responsable if I get cooked
I'm going to plug into my dryers 220 outlet and run the cord through the vent hole. Fire exinguishers are charged and ready.
I'm going to plug into my dryers 220 outlet and run the cord through the vent hole. Fire exinguishers are charged and ready.
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Oh yeah...this hippy stuff is starting to scare me. I wake up in the middle of the night thinking they're coming for me too. I think I'm going to start putting my great plains rifle under my pillow 
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ground wires go to the frame or chassis of the piece of electrical equipment to prevent a shock if the live wires going to the heating element short curcuit.
Mark Williams
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Thanks George,
I kinda figured that, just wasn't quite sure where to put it. The oven casing will be the ground point.
I kinda figured that, just wasn't quite sure where to put it. The oven casing will be the ground point.
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If the inner casing is electrically insulated from the outer shell connect the ground wire to both.
Mark, I wouldn't do that. Your drawing shows a 115 Volt autotransformer (Variac). If it did work the lowest voltage I believe you will realize across the heating element is 115 volts. L1 and L2 are two phases of 115 volts each. Using any of these two lines (L1 or L2) and the ground as a return puts 115 volts across the load (the load in this case is the heating element).
An autotransformer is nothing more than a single winding (coil) with an un-terminated pig tail as part of the winding. The AC is attached to a tap in the coil and the return ground is attached to one end of the coil and is also attached to the transformer output. The other lead of the transformer output is a wiper conection and by turning the dial, which positions the wiper on the coil, you vary the output voltage. The auto transformer is named after the 'auto effect' which allows for a certain maximum increase in votage as the wiper is poistioned past the coil tap and into the un-terminated pig tail of the coil. That is why Variacs are rated at approximately 140 - 145 volts maximum output.
RL
An autotransformer is nothing more than a single winding (coil) with an un-terminated pig tail as part of the winding. The AC is attached to a tap in the coil and the return ground is attached to one end of the coil and is also attached to the transformer output. The other lead of the transformer output is a wiper conection and by turning the dial, which positions the wiper on the coil, you vary the output voltage. The auto transformer is named after the 'auto effect' which allows for a certain maximum increase in votage as the wiper is poistioned past the coil tap and into the un-terminated pig tail of the coil. That is why Variacs are rated at approximately 140 - 145 volts maximum output.
RL
Mark Williams
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So what would this do?,burn out the variac?
Hello Mark
Please check the following three things.
Please write down everything that you see on the "nameplate" of your variac and post it here. Please also show how all of the wires or terminals on the variac are labelled. Roger is right that most variacs that are commonly available will only be rated for 110V. If it is only rated for 110V and you connect it to 220V and you have a fire, and your insurance company finds out, they probably will refuse to pay. Guaranteed safety is why there are all those little UL logos on the serial labels of your home appliances.
Please use the ohm function of a DVM (Digital Voltmeter) to check that neither of the wires from your variac that you show connected to the element or L2 of your mains supply are connected to the wire that you are showing as connected to G on your mains supply. If one of them is connected, it will short out your supply.
Please check that the element is not connected to the chassis of the oven using the ohm function of the DVM. If one end is connected, you will short out your supply when you apply power.
It appears that the connection scheme that you have shown is rather unusual. I think that you will get a range of 110V to 220V across your element instead of the usual range of 0V to 220V. I don't know if that is your intention. We use non-variable autotransformers in the UPS' that we manufacture at work. One end of the winding is always connected to Neutral or Ground. The same goes for the big, three-phase variacs that we have in our test labs.
I hope that this helps you stay safe.
Phil
Please check the following three things.
Please write down everything that you see on the "nameplate" of your variac and post it here. Please also show how all of the wires or terminals on the variac are labelled. Roger is right that most variacs that are commonly available will only be rated for 110V. If it is only rated for 110V and you connect it to 220V and you have a fire, and your insurance company finds out, they probably will refuse to pay. Guaranteed safety is why there are all those little UL logos on the serial labels of your home appliances.
Please use the ohm function of a DVM (Digital Voltmeter) to check that neither of the wires from your variac that you show connected to the element or L2 of your mains supply are connected to the wire that you are showing as connected to G on your mains supply. If one of them is connected, it will short out your supply.
Please check that the element is not connected to the chassis of the oven using the ohm function of the DVM. If one end is connected, you will short out your supply when you apply power.
It appears that the connection scheme that you have shown is rather unusual. I think that you will get a range of 110V to 220V across your element instead of the usual range of 0V to 220V. I don't know if that is your intention. We use non-variable autotransformers in the UPS' that we manufacture at work. One end of the winding is always connected to Neutral or Ground. The same goes for the big, three-phase variacs that we have in our test labs.
I hope that this helps you stay safe.
Phil
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Hippies? Whoa.... Thought Tim Lively came back online for a minute....
Is there a general resource of information on electricity for complete idiots? You talk about AC/DC and my neck starts spasming and I have high school flashbacks.... Thanks.
Tim
Where's my combat boots and flannel shirt I used to tie around my waist?
Is there a general resource of information on electricity for complete idiots? You talk about AC/DC and my neck starts spasming and I have high school flashbacks.... Thanks.
Tim
Where's my combat boots and flannel shirt I used to tie around my waist?
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Mark....Rodger and Phil are right. Question...Why are you using the Variac? The easy way to do what you want is go to the junk yard or most any inner city neighborhood and find an old stove. Pull the controls and transformer and elements off of that. hook it up in your enclosure and you are ready to go.
OH....you will need to hook to 220 and have at least 40 amps for operation. If you don't have 220 in the shop or the box won't support the load, go to hotplate controls.
Good luck!
OH....you will need to hook to 220 and have at least 40 amps for operation. If you don't have 220 in the shop or the box won't support the load, go to hotplate controls.
Good luck!
Mark Williams
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Good Idea peter,
Might run down to 25th St. and Jefferson Ave. Wading through the hookers and crack dealers is always fun with a .45 sticking out of your waistband. Junkyard would probably be safer
That 4 gauge kablammo gun you were taliking about making might do the trick
Might run down to 25th St. and Jefferson Ave. Wading through the hookers and crack dealers is always fun with a .45 sticking out of your waistband. Junkyard would probably be safer
That 4 gauge kablammo gun you were taliking about making might do the trick
Mark
Are you the one who had a post about extending an oven to temper larger pieces. If so, just use the whole oven. It already has a thermostat, ON/OFF controls as well as a safe way to connect to your power source. The thermostat has a temperature sensor that controls a switch that will apply power to your element when the temperature is too low and disconnect it when too high. Do use an oven thermometer to set the temperature. They are only a few dollars from the kitchen gadgets department of any Walmart or Target store. The thermostats in a typical house oven is not calibrated accurately. The ovens that you would buy from Paragon work the same way but have more sophisticated and accurate electronic controls. There is no need to use a variable voltage to control the temperature.
Tim
Go to your local public library and look for some books on basic electricity or home wiring. The books on home wiring should give you some good safety guidelines. It is not that hard. In fact a lot of it is somewhat like plumbing. It is when one has to make a living working with it that one has to get into the subtleties and keep up with the state of the art. There may be a book on basic electricity in the "Idiots Guide to..." or "... for Dummies" series. I saw an amazing array of titles at Barnes and Noble this weekend including "World Religions", "Party Planning", "Feng Shui" and "Home Neurosurgery".
Hope this helps.
Phil
Are you the one who had a post about extending an oven to temper larger pieces. If so, just use the whole oven. It already has a thermostat, ON/OFF controls as well as a safe way to connect to your power source. The thermostat has a temperature sensor that controls a switch that will apply power to your element when the temperature is too low and disconnect it when too high. Do use an oven thermometer to set the temperature. They are only a few dollars from the kitchen gadgets department of any Walmart or Target store. The thermostats in a typical house oven is not calibrated accurately. The ovens that you would buy from Paragon work the same way but have more sophisticated and accurate electronic controls. There is no need to use a variable voltage to control the temperature.
Tim
Go to your local public library and look for some books on basic electricity or home wiring. The books on home wiring should give you some good safety guidelines. It is not that hard. In fact a lot of it is somewhat like plumbing. It is when one has to make a living working with it that one has to get into the subtleties and keep up with the state of the art. There may be a book on basic electricity in the "Idiots Guide to..." or "... for Dummies" series. I saw an amazing array of titles at Barnes and Noble this weekend including "World Religions", "Party Planning", "Feng Shui" and "Home Neurosurgery".
Hope this helps.
Phil