Electric kettle with PID control

[scoates]

Nope. No problem. I just tossed a Marrette on the end of my neutral line. Just don't ground it (the GFCI might not like neutral being grounded).

BTW, my cheap controller works. More details to be posted in the future (-:

S

 

[slnies]

I've got my controller box all wired up, and I'm just doing some final checks. With the GFCI, will it be a problem not having the neutral connected to anything on the kettle side?

No, remember that a GFCI only compares amps across the neutral and the ground. If you short the neural to the ground on your kitchen GFCI it will trip. In theory if you do not have a load to neutral a GFCI is useless. Any voltage to ground will fault the circuit tripping the overcurrent protection device ( the breaker). If you do not have a unbalanced load you do not need a GFCI. Any load to neutral is unbalanced (example: 120v or 277v). These are phase to ground loads. 220v is phase to phase and is balanced by nature. If you do not have a load to neutral in your system I would recommend using a fuse block with fast reaction fuses as these are more accurate than a breaker and ultimately safer. When a fuse dies it is dead. The other thing to remember is that GFCI's were only invented to protect people from their own stupidity I.E. dropping the drier in a sink full of water and then reaching to retrieve it. The best way to protect yourself if you are using straight 220v is to ground everything. This creates a grounding plane and insures that if the equipment fails it will cause a fault condition. These measures do not ensure that you will not get shocked the same is true with a GFCI it just lessens the likelihood of of death. I hope this answers your question.

 

[wihophead]

No, remember that a GFCI only compares amps across the neutral and the ground. If you short the neural to the ground on your kitchen GFCI it will trip. In theory if you do not have a load to neutral a GFCI is useless. Any voltage to ground will fault the circuit tripping the overcurrent protection device ( the breaker). If you do not have a unbalanced load you do not need a GFCI. Any load to neutral is unbalanced (example: 120v or 277v). These are phase to ground loads. 220v is phase to phase and is balanced by nature. If you do not have a load to neutral in your system I would recommend using a fuse block with fast reaction fuses as these are more accurate than a breaker and ultimately safer. When a fuse dies it is dead. The other thing to remember is that GFCI's were only invented to protect people from their own stupidity I.E. dropping the drier in a sink full of water and then reaching to retrieve it. The best way to protect yourself if you are using straight 220v is to ground everything. This creates a grounding plane and insures that if the equipment fails it will cause a fault condition. These measures do not ensure that you will not get shocked the same is true with a GFCI it just lessens the likelihood of of death. I hope this answers your question.

Sorry but you should really learn how a GFCI operates before you give advice and as far as the balanced and unbalanced load goes, how does that apply to a GFCI.

A GFCI monitors current flow between 2 current carrying conductors, a ground is not even required for it to function.

The only thing that I would agree with here is that you should ground everything.

 

[wihophead]

Yes, and no it is not illegal on residential power or at least the NEC does not forbid it. How ever According to that same NEC unless all of the parts of the system are listed for the intended use or for use with the individual parts of the system. you would be in violation. The way around is to have a EE approve the drawings and UL list the system. This however is not practical for use lowly Home Brewers.

That would be covered by individual municipalities.
The NFPA 70 was put in place to protect persons and property and does not cover power quality.


Switching power supplies such as the ones use in computers for residential use must be FCC approved not to mention most if not all switching power supplies are now required to come with power factor correction.
I am not sure if switching a load on and off quickly would pose a problem in a given municipality but I can tell you that it is not the same as a switching power supply.
A switching power supply is a non-linear load which the power company frowns on because of the harmonic currents they create.

If you want more info on this simply look up non-linear loads.

 

[mr x]

I am not sure if switching a load on and off quickly would pose a problem in a given municipality but I can tell you that it is not the same as a switching power supply.
A switching power supply is a non-linear load which the power company frowns on because of the harmonic currents they create.

In my country, they frown on all short cycle heavy amperage power switching.

 

[wihophead]

In my country, they frown on all short cycle heavy amperage power switching.

Yes, I would imagine it would depend heavily on the size of the infrastructure.
I believe Europe was one of the first pushing for PFC on all residential computer power supplies.

Sorry one more thing about GFCIs....I had a little too much to drink last night and forgot one key point.....

I will make it short and simple because there are just too many scenarios to cover.
Depending on the size of your over current protection device it will take anywhere from 15 to 50 amperes for quite a few cycles to clear a fault and it only takes 50milliamperes to kill you, a GFCI designed to protect persons will clear at an imbalance of ~5mA for ~2cycles.

A circuit breaker is designed to protect property, a GFCI is designed to protect life.

Also there is a potential for a GFCI to catch a fault before it becomes a dead short or ground fault.....just because a breaker says it clears at 15A does not mean that is the maximum current it will see because it takes several cycles to clear. This is the reason most branch circuit breakers are rated at 10000 amperes RMS symmetrical and mains are rated much higher ~21K amperes RMS symmetrical. A typical home may see current in the excess of 9KA during an event. I work in industry so the risk is much higher, this is why Arc flash is pushed so heavily in our trade.

 

[slnies]

Sorry but you should really learn how a GFCI operates before you give advice and as far as the balanced and unbalanced load goes, how does that apply to a GFCI.

A GFCI monitors current flow between 2 current carrying conductors, a ground is not even required for it to function.

The only thing that I would agree with here is that you should ground everything.

I hate being wrong. Today i was having a talk with one of our apprentices and he wanted to know more about GFCI's and I said" GFCI's are a comparative circuit device that compares what's going in to what's going out..." and then I went son of a... #*&^!!! so I am sorry for the miss info. I will say that in a 220 application even involving water that a GFCI is not always the best choice. In the case of a brewing system as long as the loads are balanced you should be good, this also means that a motor load of any kind may not work with a GFCI do to how the motor is built in the first place. S.

 

[slnies]

Yes, I would imagine it would depend heavily on the size of the infrastructure.
I believe Europe was one of the first pushing for PFC on all residential computer power supplies.

Sorry one more thing about GFCIs....I had a little too much to drink last night and forgot one key point.....

I will make it short and simple because there are just too many scenarios to cover.
Depending on the size of your over current protection device it will take anywhere from 15 to 50 amperes for quite a few cycles to clear a fault and it only takes 50milliamperes to kill you, a GFCI designed to protect persons will clear at an imbalance of ~5mA for ~2cycles.

A circuit breaker is designed to protect property, a GFCI is designed to protect life.

Also there is a potential for a GFCI to catch a fault before it becomes a dead short or ground fault.....just because a breaker says it clears at 15A does not mean that is the maximum current it will see because it takes several cycles to clear. This is the reason most branch circuit breakers are rated at 10000 amperes RMS symmetrical and mains are rated much higher ~21K amperes RMS symmetrical. A typical home may see current in the excess of 9KA during an event. I work in industry so the risk is much higher, this is why Arc flash is pushed so heavily in our trade.

On that note, you forgot that in a house hold if you do the math you fault rating one the line side is in access of 41k and a breaker is only rated for 10k which means that your property is not protected from the power company unless you fuse. That is why the code now requires coordination of equipment. You are correct about the breakers ability( good example of bad breaker "FPE") and you are correct about arc flash hazard. Most fuses are rated for 100k rms and can be had in ratings as high as 1M. This is also why your typical 1200-3000 amp switch gear is fused. Note that they are gfci protected above 1000 amps or 1000V nominal. This however is not for life protection it is for fire protection. You are also correct about the limits of a GFCI and that is why they are a good idea. One should note that a GFCI is no guarantee of safety unless properly monitored and tested. This goes for all electrical equipment.

 

[slnies]

That would be covered by individual municipalities.
The NFPA 70 was put in place to protect persons and property and does not cover power quality.


Switching power supplies such as the ones use in computers for residential use must be FCC approved not to mention most if not all switching power supplies are now required to come with power factor correction.
I am not sure if switching a load on and off quickly would pose a problem in a given municipality but I can tell you that it is not the same as a switching power supply.
A switching power supply is a non-linear load which the power company frowns on because of the harmonic currents they create.

If you want more info on this simply look up non-linear loads.

You are talking about electronic power switching which also causes Freq spikes and hysteresis and also plays havoc with the power supply. Note that the power company frowns on anything that can cost them money. Even if power factor correction wasn't required by parts of the code the power company does, and if you don't comply they charge you for it to the tune of 10s of thousands. Should also note that this covers motor loads and transformer loads. Motor loads in abundance usually account for a lag or a lead in power factor Example: 1000hp westinghouse motor.

 

[slnies]

One more thing before this gets to fare out of hand. We are here to provide good advice to a fellow home brewer, the rest of our ramblings are really a debate on the finer points of electrical theory, and code. Points of which we do not have to agree on completely. So for the record i think we should " relax and have a home brew." Charlie P. S.

 

[neo82087]

I'm confuse now

and PHEW a dipole single throw 250vac 30amp switch is hard to find and expensive!

 

[wihophead]

On that note, you forgot that in a house hold if you do the math you fault rating one the line side is in access of 41k and a breaker is only rated for 10k which means that your property is not protected from the power company unless you fuse. That is why the code now requires coordination of equipment. You are correct about the breakers ability( good example of bad breaker "FPE") and you are correct about arc flash hazard. Most fuses are rated for 100k rms and can be had in ratings as high as 1M. This is also why your typical 1200-3000 amp switch gear is fused. Note that they are gfci protected above 1000 amps or 1000V nominal. This however is not for life protection it is for fire protection. You are also correct about the limits of a GFCI and that is why they are a good idea. One should note that a GFCI is no guarantee of safety unless properly monitored and tested. This goes for all electrical equipment.

You are intermixing residential and commercial equipment which is not a good idea....when I stated a GFCI protects life I was referring to residential.
GFCIs that protect equipment are a different animal and do not have to clear a fault at ~5ma in 2 cycles

This is also an inaccurate statement
"Most fuses are rated for 100k rms"
It would simply not be cost effective.
Did you ever watch the video put out by Bussman on the importance of selecting the proper fuse, I thought that was a classroom standard...

I work for General Electric and all of are switch gear are programmable breakers with GFCI protection


I would like to know how you calculated residential maximum transformer fault at 41K. This is solely based on the transformer that feeds your residence. To calculate it, you would need to know the transformer impedance or call your power company. Power companies will not install a transformer that would put out a higher transformer fault current then standard residential equipment can handle, which is generally ~21KA at the main principal. How often do you see a modern residential service with fuses ahead of the main panel....hell most insurance companies (in WI at least) are refusing to insure houses with fuses at all do to the fact there is a chance someone could install an improper fuse.

 

[wihophead]

I'm confuse now

and PHEW a dipole single throw 250vac 30amp switch is hard to find and expensive!

You should be able to get a single throw double pole toggle switch rated for 30A 277V for $10-$15
Have you tried a local electrical supply shop not a home improvement store?
Otherwise I am sure you could find one online.

 

[neo82087]

My work so far:

This is the kettle that I am doing construction on. It is a 60qt Aluminum stock pot from Instawares

Hardware: one 4500 watt 240vac ultra-low density element, two 1 1/2" silicone O-rings (part 1RFG7 from Grainger), one 1" ID 1 1/4" OD stainless steel hex bushing (McMaster 4464K151), one 1 1/4" SS pipe locknut (Grainger 1LUL3), and one 1 1/4" steel locknut from HD (not pictured here, but can be seen below)

Marked for drilling, used a center punch to make drilling the pilot hole easier

1 1/4" bi metal hole saw (ended up having to sand quite a bit to make it larger, the hex bushing was more like 1 1/2")

 

[neo82087]

Hole is drilled and ready for construction

View inside the kettle

Added a locknut and plenty of teflon tape for a water-tight seal and installed the 4500 watt 240vac element

Another look inside

 

[neo82087]

Hm... why are the images not showing up??


edit... got it

 

[scoates]

Seems blogger doesn't like sharing images.
Email me privately, and I'll try to resolve your issue with being able to post on the montrealers site.

S

 

[mr x]

They show up now.

 

[neo82087]

So I decided to test out the GFCI today and I followed the instructions on the
back of the GFCI. Hit the test button and it shut off the power to my
controller, but when I hit the reset there was a substantial spark and the
circuit breaker tripped. Don't think that's supposed to happen... kinda scary! I
am just wondering why that would happen. Yikes!

 

[slnies]

So I decided to test out the GFCI today and I followed the instructions on the
back of the GFCI. Hit the test button and it shut off the power to my
controller, but when I hit the reset there was a substantial spark and the
circuit breaker tripped. Don't think that's supposed to happen... kinda scary! I
am just wondering why that would happen. Yikes!

Inrush current from the rest of the machine. If, just the control were on when you went to reset, it most likely will not trip when you reset. The other explanation is that you have a ground fault but from the looks of the pick up above the element is insulated from the pot, however this doesn't say anything about the rest of the wiring. Either way, I would try to reset it a couple of times first. If it turns back on your O.K. if not then it is time to break out the meter and track down the fault. A couple of questions though. Did you calculate the circuits load? Did you create a grounding plan? ( Ground everything, extreme like)
Thats it for know. S

 

[neo82087]

I checked the wiring and I am fairly certain there is not a ground fault. Even so, why would that cause the GFI to spark and the circuit breaker to trip? According to my understanding of the GFI, that is what is is supposed to detect and shut off. I have grounded everything in my circuit that has metal on it. I have not calculated the circuit's load. I am somewhat concerned to use the plug again because there is black burnt residue coming out of the side of the box where the GFCI is housed and where the spark occurred. I also am not sure I understand the concept of an Inrush Current which you have suggested as a possible cause.

 

[wihophead]

I doubt it is an inrush current problem especially if it is just a heater that you are controlling. With a heater, like an incandescent light bulb there will be a current spike when you turn it on until the heater warms up which causes the resistance to increase in turn lowering the current. Inductive and capacitive loads are much more likely to cause problems with inrush currents, motors probably being the worst. Do to the fact you had arcs and burning I would say that something is definitely wrong. I would highly recommend you find someone locally that can look at your wiring or at the very least take some detailed picture so maybe someone can help you.....good luck and be safe

 

[slnies]

I doubt it is an inrush current problem especially if it is just a heater that you are controlling. With a heater, like an incandescent light bulb there will be a current spike when you turn it on until the heater warms up which causes the resistance to increase in turn lowering the current. Inductive and capacitive loads are much more likely to cause problems with inrush currents, motors probably being the worst. Do to the fact you had arcs and burning I would say that something is definitely wrong. I would highly recommend you find someone locally that can look at your wiring or at the very least take some detailed picture so maybe someone can help you.....good luck and be safe

I agree with WIhophead on this one. He is right that inrush is not normaly a problem with resistive loads, that being said electricity is a mysterious bed fellow. There are people who dedicate their lives to figuring out all of it secrets, we know a lot, but that only scratches the surface. S

 

[BrewBeemer]

I was thinking about this SSR; http://www.teledynerelays.com/industrial/sd.asp
This dual SSR SD Series up to 50 amps/ 600 volts.
The DRD Series SSR up to 25 amps w/heat sink.
Both units are two relays in one package, need a heat sink for the 50 amp unit, best used with a cooling fan. I haven't a clue on their prices.

 

[BrewBeemer]

Does anyone have a source on heat sinks?

 

[bakins]

This is where I bought my PID's, SSR's and heat sinks:

http://www.auberins.com/

 

[BrewBeemer]

Those are only 25 amp besides I want to use SSRD's without operating them at their maximum capacity. Yes I already looked at what that company had to offer. Thanks for the reply.

 

[neo82087]

Check e-bay, you can find many SSR's there

 

[King of Cascade]

+1 on auberins.com, Temperature control solutions for home and industry fast service

 

[cyberbackpacker]

My work so far:

Hardware: one 4500 watt 240vac ultra-low density element, two 1 1/2" silicone O-rings (part 1RFG7 from Grainger), one 1" ID 1 1/4" OD stainless steel hex bushing (McMaster 4464K151), one 1 1/4" SS pipe locknut (Grainger 1LUL3), and one 1 1/4" steel locknut from HD (not pictured here, but can be seen below)

What is the difference between the Grainger 1 1/4" SS pipe locknut, and the 1 1/4" steel locknut you got from HD?

Thanks, as I really like the way you have yours installed, and I think is the best solution for mounting an element in a kettle without having a fitting welded in.