Variac for Idiot Part 2

[sdumper]

Ok I cant seem to find any diagrams that make sense for wiring my variac.

Here is a pict of the front, back, top and bottom.

Do I wire to the screws on the top of the variac and if so which screws get my power in from my power cord and which screws go to my load tester?

http://i190.photobucket.com/albums/z294/sdumper/IMG00212.jpg





http://i190.photobucket.com/albums/z294/sdumper/IMG00213.jpg

[wdrzal]

That got me stumped........The should be 2 terminals that are electrically isolated from the metal case.

[sdumper]

Looks like there are 2 punch outs at the top. Am I supose to punch those out and wire through that somehow?

opps dangerous pict

[sjg0]

Yea its meant to be punched out. But dont do that yet, unscrew the case first and take it apart. If you can, take pics of inside.

[wdrzal]

Is there a place where the power cord goes in ? I don't see that on the pics. It's possible you have a varic that needs to be "hard wired".

If it's to be hard wired you will still need to open the case up ,so I would do that first.

If you try to punch those knockouts without disassembly you risk punching one into the windings and causing damage.

It appears you should use 2 romex connectors for wire strain relief .

[sdumper]

All the goodness was tucked away inside picts in a minute

[sdumper]

Now for the wiring help part 2 :--)

http://i190.photobucket.com/albums/z294/sdumper/IMG00220.jpg

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http://i190.photobucket.com/albums/z294/sdumper/IMG00222.jpg

[sdumper]

Ok I have 3 schemes

a: 0 -140 volts, b: 0 -120 volts c: 0 - 280 volts

I think a: is fine and I dont think it matters where my black or white wires go correct.
What about the wires from the load tester?

Looks like they go to 2 and 3 right? Diagram "a: (0-140) up close...

http://i190.photobucket.com/albums/z294/sdumper/IMG00230.jpg

[wdrzal]

That's a multi tap variac so you have the option of 120v or 140 volts on the secondary side using 120v on the primary side. The next question is: are you going to use a watt meter or measure the amps & voltage to determine the wattage as you adjust the voltage ? I see most guys use a watt meter.

[sdumper]

I dont have a watt meter so will need a cheat sheet to know what im getting with diff settings such as 125 watt, 200 watt 250 watt and 300 watt.

heres what i did for the 0-140 wire hopfully i did it right but not sure where to put ground wire.

Black power wire and two bottom load tester wires are going to (2) the two top load tester wires are going to (3) and the white power wire is going to (5)

http://i190.photobucket.com/albums/z294/sdumper/IMG00230.jpg
http://i190.photobucket.com/albums/z294/sdumper/IMG00233.jpg

[sjg0]

Do you have a multimeter? That would help.

Anyway, I think hooking up your cartridge heaters directly to the internals of the variac is not so good an idea. If possible, go to radio shack or something like that and get banana jack plugs. Then punch out those holes and hook em up to there.

Also, While your there, get some heatshrink.
Technically this stuff is unnecessary, but it will make your life easier.

For wiring, I cant really see whats going on, but it looks ok. Buy a fuse at Radio Shack too(IMPORTANT).

[sdumper]

Too late...

[ruffus]

if that thing on the bottom of your load tester is a heat switch then u need to use it like one so one wire from each of the cartridge heaters have to go to one of the 2 spades on it and then u would put the other spade to the 3 screw on your varic and then the other 2 wires from your cartridge heaters go to the 2 screw. if this is how u have it the i would think that u would be good to go. but i am with the other guys u should have your varic set up so u can easly un hook your load tester. and for the ground wire i would think u could just ground it to the case of the varic

[sdumper]

Bummer it was such a major pain to put this back togther....oh well I just noticed that a simple back plate isnt going to hold it down right anyway....

[sjg0]

Too late...

What do you mean "Too late" ?!?!

Seriously at least buy a fuse!

[sdumper]

I already sealed it up...but as the post above stated I will need to rewire anyway.

Whats with the "?!?!" did I write something that was rude?

[[XC] Hicks121]

If you dont have a meter, you REALLY need one bud. :yepp:

Also fuse it up so you dont fry anything. :up:

[sjg0]

Whats with the "?!?!" did I write something that was rude?

No, its just in my mind i read it as a very trite "nope too late", to which my reaction was a "wtf???" of sorts.... :rolleyes:

And you just made it sound like putting it back together is irreversible, and I didnt yet catch the post saying you needed to open it up again anyway. :p:

[sdumper]

http://i190.photobucket.com/albums/z294/sdumper/IMG00234.jpg

Still not sure what you mean about a fuse can someone explain what kind of fuse to use and where it goes?

[ruffus]

well this fues is a thermal fues which will blow at a its set temp. i think that is what they mean if not they mean just a fues so that if u get a surge that it does not burn out anything. now that i am thinking u have done your the same way i did mine and i don't use a thermal fuse as i have the thermal switch like u do. but u can't go wrong if u use a fues to stop any surges.

[sdumper]

Thanks Ruffus...

Spent about 40 minutes trying to explain to the guys at lowes and ace what I was trying to do and why I needed a fuse. They eventually gave up on me and told me to come back at 5:00pm when the senior electrical guy comes in...

Oh well still needed to get some basic supplies so the trip wasnt wasted :-)

Hey Sjg0 im not the kind of guy who would be a jerk on purpose sorry I came across that way :)

[sdumper]

Any way Load Tester to Variac wiring complete and works perfectly :)


http://i190.photobucket.com/albums/z294/sdumper/IMG00235.jpg

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http://i190.photobucket.com/albums/z294/sdumper/IMG00237.jpg

[sjg0]

http://www.radioshack.com/product/index.jsp?productId=2103768

Thats exactly what you need (your variac is 5A right?). To install it, cut your black (hot) wire and place this in between the separated wires. Polarity doesnt matter so either way works. You will need to buy a fuse holder too, because if you try to solder it directly to the wire you risk poping the fuse lol.

Ugh, i wouldnt worry about a thermal fuse because its a pita to find one with the exact specs you need. Plus you will hopefully have your K-type probe on there anyway, so just make sure your temps are in the (-) lol.

Once you get all that straightened out, insulate, and you should be good to go!

No no no, dont worry i dont think your a jerk, it was just a little odd.... nm....

[sjg0]

Now that I think of it, its a good idea to pick up a simple rocker switch too for ease of use so you dont have to unplug every time your done. But that's just like what I would do....

[DetroitAC]

This variarc is a DC model not AC so disregard that ground

only the case an block should be grounded (green wire)

It's a DC model? Where are you getting that? The wiring diagram specifies AC.

Looks good Scott, I would suggest wiring the entire load block apparatus to a three prong plug, and putting a three prong receptacle in the knockout of the variac. That'll make it not so cumbersome, but if you're Ok with how it is then leave it. I also think you should run a ground wire to the variac case and the copper block. I just mount it to one of the thermal switch screws with a ring terminal.

[sdumper]

It's a DC model? Where are you getting that? The wiring diagram specifies AC.

Looks Scott, I would suggest wiring the entire load block apparatus to a three prong plug, and putting a three prong receptacle in the knockout of the variac. That'll make it not so cumbersome, but if you're Ok with how it is then leave it. I also think you should run a ground wire to the variac case and the copper block. I just mount it to one of the thermal switch screws with a ring terminal.

cool man will do :)

sent you a message via paypal btw.

[sjg0]

SJG0 that's a current fuse (amp)

the 1 Sdumper looking for is a thermal type that blow when reach a temp, but need to buy alot of them for are 1 time application

best use a therm-stat witch are re-setting type

Yes I know that. He needs a current fuse on there. Hence why i posted the link for him.

On the other hand, he does not need a thermal fuse because a) he already has one and b) its not very necessary so long as he has his thermometer hooked up to it (which he will when tuning) and knows to shut it off well before it reaches 160C (at which point it will probably already be damaged so the thermal cutoff @ 160C like in your pic is pointless).

[Planet]

You should always use a thermal cut off on load testers. Even if he has his thermometer hooked up what if he walks away or the phase unit fails. Its never a bad idea to have more than one safety cut off. Also thats a 70C cutoff not 160C

[teyber]

Yes I know that. He needs a current fuse on there. Hence why i posted the link for him.

On the other hand, he does not need a thermal fuse because a) he already has one and b) its not very necessary so long as he has his thermometer hooked up to it (which he will when tuning) and knows to shut it off well before it reaches 160C (at which point it will probably already be damaged so the thermal cutoff @ 160C like in your pic is pointless).

im not sure if you have ever seen a phase unit running(i assume not) but if you have ever seen one crash you will understand why you need one.

i burned my load tester, a unit with a controller was holding a load fine, i was in the bathroom if i remember the temps raised to about 10c the controller shut the unit off adn within seconds my garage was filled with smoke... still hard feelings with a member of the forum about that one :(

until you get experience with phase change its best not to make statements, rather suggestions, unless you really know what your talking about. Hell, i dont' know what im talking about, but i sure know how much it blows to have a load tester issue :rolleyes:

[sjg0]

im not sure if you have ever seen a phase unit running(i assume not) but if you have ever seen one crash you will understand why you need one.

Yea actually my neighbor is the VP of Honeywell and he has sorta been helping me out the past few months. He actually has quite a few cascades in his garage and offered to give me one because it was taking up too much space in his garage. In other words, yes i have seen a system crash, i have seen one, etc etc...


i burned my load tester, a unit with a controller was holding a load fine, i was in the bathroom if i remember the temps raised to about 10c the controller shut the unit off adn within seconds my garage was filled with smoke... still hard feelings with a member of the forum about that one :(

Yea.... i thought it was common sense to always monitor your systems.... especially in the middle of tuning but ok, sorry to hear about your unfortunate incident. You wouldnt leave your acet torch on when you go to the bathroom would you? Sorry to had to learn that this is dangerous stuff the hard way :(



until you get experience with phase change its best not to make statements, rather suggestions, unless you really know what your talking about. Hell, i dont' know what im talking about, but i sure know how much it blows to have a load tester issue :rolleyes:

True, im not the most experienced on these forums, but honestly is just common sense. Your going to have a thermometer on the load tester anyway, and when tuning you should be monitoring it quite often, so the only advantage of the thermal fuse is it will shut off automatically instead of you manually pulling the plug when your thermo starts reading positive numbers.

Besides, imo, the thermal cutoff at 160 degrees is too much and defeats the purpose of having it. By the time it actually trips "the garage will be filled with smoke"


Edit - Sorry for off-topic OP

[sjg0]

You should always use a thermal cut off on load testers. Even if he has his thermometer hooked up what if he walks away or the phase unit fails. Its never a bad idea to have more than one safety cut off.
While i agree there is no such thing as too many fail-safes, common sense saves 99% of fails. This is dangerous equipment, you wouldn't leave the room with your acet torch on would you?


Also thats a 70C cutoff not 160C

oops lol didnt catch that its F not C. Either way though, 70C is still to much imo, personally i would get one that is 20C-30C cutoff.

[sdumper]

Yea actually my neighbor is the VP of Honeywell and he has sorta been helping me out the past few months. He actually has quite a few cascades in his garage and offered to give me one because it was taking up too much space in his garage.




Im confused I thought you had been building for awhile.

[ruffus]

well i have the same thermal switch that he is useing and mine opens at 85c and i have had a system shut down on me and the load tester and evap get to about 90c and it shuts off the load tester. i find that it works good. but yes i am with the guys u need to have a fuse before the varic just incase u get a surge. it will save your varic and alot of time and money

[sdumper]

Wouldn't I just trip a circuit breaker?

Exactly what type of fuse do you recommend I really need fuse details and a link to the fuse housing because I wasted almost an hour today with Lowes and ACE who both thought I was crazy :--)

[SexyMF]

Wouldn't I just trip a circuit breaker?

Not a given. What if the fault condition means your circuit is drawing 7Amps? You will wreck your variac before the circuit breaker trips.

Get a panel-mount fuse holder and mount it into the variac case. Do not use an in-line use holder. These are really meant for low voltage/DC circuits.




There is a lot of harping on about the dangers of high pressure gases, but I am more concerned about people doing mains wiring (and those builders who are not electrically qualified and sell there wares).
On one hand, we can recommend parts to you, but quality control is beyond our control. Variacs are dangerous. They present a whole raft of failure modes.

[sjg0]

its 160 F

the idea! its a pic shown a unit not the set-point to use an yes most wafer would be toast but to illustrate are safety devices other than thermFuse

I dont exactly get what you are saying here but i think your trying to say that pic was just an example to illustrate the difference between a one-time use fuse and a resetting one? Alright gotcha.


Wouldn't I just trip a circuit breaker?

Eventually yes, but by that time all your equipment would be destroyed. Your variac can handle a max of 5A. Typical houses are wired with 15A circuit breakers(some rooms 20A, dryer 30A). So if your variac starts drawing say 10A, then it will fry, and the circuit breaker will be totally unaffected until it draws more than 15A.


Exactly what type of fuse do you recommend I really need fuse details and a link to the fuse housing because I wasted almost an hour today with Lowes and ACE who both thought I was crazy :--)

If im not mistaken, the variac you have there is 5A no?
In that case you will want the fuse i posted a link for(yes that exact one).

Here it is again:
http://www.radioshack.com/product/index.jsp?productId=2103768
http://www.radioshack.com/product/index.jsp?productId=2062257

There is a fuse holder too.
Im sorry you wasted an hour at those places :(
But if you told them "I need a fuse for a Variac" thats why. Variac stands for variable AC transformer, and even if you said that they would have no idea what your talking about so they cannot give you the proper fuse. Anyway, you need a ~125V fuse that will pop at 5Amps.

[wdrzal]

140v * 5A = 700W the resistance will be 28 ohms. I doubt those cartridges total 700 watts but it doesn't matter. I just used the maximum output value of 140v * 5A sdumpers Variac.

lets say @ the maximum of 140V the temperature of the block increases and thus the resistance,say to 35 ohms.
140v @ 35ohms = 4A producing 560W . As the block temps increases the resistance increases (ohms) thus the current Falls. So the Variac won't be harmed . The Hi-temp cut out will prevent overheating.

The point being: Current drops as resistance goes up with a set voltage.

[sdumper]

Thanks Walt so I should be ok with just using a standard surge protector and the thermal cut off switch which Eric already has attached to the load tester right?

[wdrzal]

^^^^^^^Yep, there is probably a fuse or more likely a fusible link set @ just above 5 amps Incorporated into the Variac.

[wdrzal]

As a further example: say sdumpers block is getting hot and @ the 35 ohms used above but @ 100 volts.

The heat out put would be 285.714 watts @ 2.857 amps of current.

As long as the Variac is not undersized for the cartridges wattage your OK.



Now most use around 300 to 400 watt cartridges (single or combined), keep in mind though, as the block is cooled with your phase unit,the cartridge resistance will go down and thus the current will go up for a given voltage. So when buying a variac used the way we do here ,you need to oversize a bit. How much???? well that depends on how low of a temperature you reach and what the resistance(ohms) of the given cartridge is @ that Temperature.

[wdrzal]

Watt Density has to do with Where the distribution of heat is from the cartridge. Say a 700 watt cartridge 1.5 inches long, may reach 1000 watt density at the center 1.25 inches,but 500 watt density peak @ the ends . Doesn't mean it will draw over 700 watts @ rated temperature.

Watt density is how and where the heat is distributed from a cartridge,(they are not completely uniform) does not have anything to do with the rated electrical data total.

[ultralo1]

SJG0 that's a current fuse (amp)

the 1 Sdumper looking for is a thermal type that blow when reach a temp, but need to buy alot of them for are 1 time application

best use a therm-stat witch are re-setting type

You can find those at your local CC Dickson. They even make an adjustable temp temp Limit switch (Therm-stat)

[sdumper]

Actually the heatloader has a built in thermal switch. My heatloader is one I bought from DetroitAC as pictured here :)

http://www.xtremesystems.org/forums/showpost.php?p=3593816&postcount=36

[sdumper]

Not sure exactly how to calculate load for a particular variac setting can someone help me out.

All I know is that my Variac is wired like this for 0 to 140 volts and im using a heat loader from Eric with dual 150 watt cartridges.

Line: 120 volts, 50 to 60 c/s
Load: 0 - 140 volts
Load Tester: 2 - 150 watt cartridges pictured here: http://www.xtremesystems.org/forums/showpost.php?p=3593816&postcount=36

http://i190.photobucket.com/albums/z294/sdumper/IMG00230.jpg

[sjg0]

Buy this:
http://www.amazon.com/P3-International-P4400-Electricity-Monitor/dp/B00009MDBU/ref=pd_bbs_sr_1?ie=UTF8&s=electronics&qid=1233603585&sr=8-1
You stick that in between the wall and the electrical cord, and it measures how many Watts you are drawing.
Just keep in mind a +/- 10% inefficiency. So even though its pulling 200W from the wall, maybe only 185W will actually be converted to heat.

Or you could do it the more complicated way as others have suggested, using a Amp meter/multimeter and Ohm's Law.

Or you could do it the ridiculously complicated way as i believe wdrzal suggested, taking into consideration resistance/change in resistance due to change in temperature. :ROTF:
Note: When dealing with bigger circuits definitely do it this way.

[sjg0]

Actually, its a good idea to get a Kill-A-Watt anyway, even if you do it the multimeter way, because with that you can:
-Calculate the efficiency of your unit and if efficiency is really bad that usually means your straining your compressor.
-Find out how much electricity various appliances use, and thus be more energy-conscious and save money on your electric bill :up:

[ultralo1]

Somebody posted a nice pic of an ohms law chart a while back. I think it might have been in the other variac thread. You need those formulas. The one formula i think i remeber is "I2 X R=W" current squared times resistance equals wattage.

Try to find the watts formulas.

[sjg0]

Somebody posted a nice pic of an ohms law chart a while back. I think it might have been in the other variac thread. You need those formulas. The one formula i think i remeber is "I2 X R=W" current squared times resistance equals wattage.

Try to find the watts formulas.

Correct-o-mundo!
Behold, the holy formula wheel!:

[sdumper]

Correct-o-mundo!
Behold, the holy formula wheel!:


Ok but all that I know is the V parameter so where do I get the others?

ergo 0 - 140 volts.

[sjg0]

Ok but all that I know is the V parameter so where do I get the others?

ergo 0 - 140 volts.

Let me paraphrase my previous post:
You have two options, buy a Kill-a-Watt or buy a Multimeter.

:up:

[sdumper]

Err why buy a multi meter I have three already?

--Edit-- Not trying to be sarcastic but I would rather not stick a multimeter around a variac because frankly it makes me a bit nervous.

Im going to buy a " Kill A Watt Electricity Usage Monitor" because it will serve me well for many things.

[sjg0]

Err why buy a multi meter I have three already?

--Edit-- Not trying to be sarcastic but I would rather not stick a multimeter around a variac because frankly it makes me a bit nervous.

Im going to buy a " Kill A Watt Electricity Usage Monitor" because it will serve me well for many things.

Oh my bad sorry I didnt know you already had a multimeter.
But if your nervous with it then its good your getting the Kill-a-Watt for simplicity sake.

[wdrzal]

If you can measure the voltage and the amps jut plug those 2 numbers into this calculator.

http://www.chromalox.com/resource-center/calculators/ohms-law.aspx


Any 2 parameters will give you the other 2.

[Sgrios]

In my experience.. (Going to bold that)
A kill-a-watt meter is terrible at measuring inductive loads, accurately.
Inductive loads: motors, compressors.

Another note about Kill-a-watt meters, the sampling rate is very low in my experience, compared to meters my fluke.
IE. It can miss quick spikes or surges in usage.

I've also had issues when monitoring power supplies with a kill-a-watt.

[sdumper]

Doesn't have to be perfect because I stay up to date on the latest intel/AMD offerings so once I get a ball park comfort level I will finish my tuning on a real CPU.

[ultralo1]

--Edit-- Not trying to be sarcastic but I would rather not stick a multimeter around a variac because frankly it makes me a bit nervous.



Usually you have to change the leads over to the AMP plugs/holes, then you have to install the unit in seris in the circuit. Unless you have an AMP clamp.

[teyber]

If you can measure the voltage and the amps jut plug those 2 numbers into this calculator.

http://www.chromalox.com/resource-center/calculators/ohms-law.aspx


Any 2 parameters will give you the other 2.

nice find! :up:

[SexyMF]

The load-tester presents a purely resistive load so watt meters are fine. Most watt meters give you power factor anyway.

I suggest you use eyelets or fork connectors to mount the wire the screw terminals.

[sdumper]

Thanks for the help guys!!