Electric kettle with PID control

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I'm confuse now :drunk:

and PHEW a dipole single throw 250vac 30amp switch is hard to find and expensive!
 
slnies said:
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.
 
neo82087 said:
I'm confuse now :drunk:

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.
 
My work so far:

ekettle+001.jpg


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

ekettle+003.jpg


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)

ekettle+004.jpg


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

ekettle+006.jpg


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")
 
ekettle+008.jpg


Hole is drilled and ready for construction

ekettle+009.jpg


View inside the kettle

ekettle+016.jpg


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

ekettle+014.jpg


Another look inside
 
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
 
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!
 
neo82087 said:
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
 
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.
 
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
 
wihophead said:
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
 
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.
 
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.
 
Can I ask a question? I was under the impression that the threads on the water heater elements were no NPT, but actually NPS, or BSP... straight threads and not tapered like normal pipe threads?
If this is the case, McMaster has a brass Hex Bushing (4978K181) that could be married up with the complimentary brass BSP components to build this same bulkhead, with brass, and using the BSP threads that will match those on the water heater element.
 
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