The electromagnet (left side of picture) causes the contacts (right side of picture) to close.
How Does a Relay Work?
Reader Response: Firing the lid separate from a pot
Recent Q&As: A digital kiln in an older home; firing clay in a glass kiln; how a downdraft vent affects the Kiln Sitter cone
HOW DOES A RELAY WORK?
Relays turn on the heating elements of digital kilns. The relays make that clicking noise that you hear while the kiln fires. I have included a photo of the inside a relay to help you to understand how it works.
A relay contains a small electromagnet. When the controller needs to turn on the kiln's heating elements, it sends a 12-volt signal to the electromagnet, which then pulls a pivoting bar toward the magnet. The bar, in turn, releases a pair of electric contacts, which allows them to come together. The elements are wired to the relay so that when the relay contacts close, electricity flows to the elements.
The contacts inside the relay are positioned on the end of spring strips. When the signal from the controller turns off, the electromagnet loses power, and the spring strips separate the contacts.
As you can see, the digital controller does not turn on the heating elements directly. It uses separate relays because they are inexpensive to replace. The relays would be costly to replace if they were built into the controller.
Last week I recommended firing the lid on top of the pot in the stoneware glaze firing. A reader asked, “Won't the lid stick to the top? Or since it is stoneware they do not glaze the top edge of the pot or the bottom edge of the lid?”
Yes, the lid will stick if glazed along the rim where it touches the pot. Where the lid and pot touch must be free of glaze. It is okay to fire the lid on the pot during the bisque firing. Try firing the top separately during the bisque firing if you are having problems with glaze pinholing on the inside of the pot.
Q. I live in an older house that has ungrounded 120-volt outlets. Will that affect a digital controller?
A. Yes. A digital kiln needs a circuit with a grounding wire. This helps the controller to dissipate random electrical “noise” that might otherwise cause error messages.
Q. I have a Paragon Fusion-7. Can I fire clay in this kiln?
A. The maximum temperature of the Fusion-7 is 1700 degrees F. You can fire it to cone 09 but no hotter. Cone 09 is pushing the kiln to its maximum, so I suggest not firing to that temperature regularly. The elements will last longer at glass fusing temperatures.
Q. Does the cool air from the Vent Master affect the bending of the cone in the Dawson Kiln Sitter / Orton Auto-Cone?
A. The Vent Master has almost no effect on a cone in the Kiln Sitter / Auto-Cone, according to Orton. The airflow through a kiln is reduced to almost a static condition when the kiln reaches temperatures above 1000F. This is because the air expands and becomes lighter as it is heated. The volume of air pulled into the kiln when the cone is at bending temperature is so small that it has no effect on the cone.
“When you concentrate on making a pot, you have no time to dwell on your problems. I know a therapist who used clay in working with suicidal teens. She has worked wonders with these kids.” --Mike Gordon
Last year, Long Beach, California customs agents found a blue 1965 VW van in a shipping crate. The van had been stolen 35 years earlier and had been forgotten in storage. That van reminded me of a blue 1967 VW van that I sold to the John Hohenshelt, owner of Paragon Industries. (He is the father of John Jr., the company president.) John Sr. was going to use the van as a company vehicle.
Before I handed John Sr. the keys, he said, “Now Arnold, if the engine blows up next week, you and I are just going to laugh about it.” We laughed at his statement as I handed him the keys.
Sure enough, the engine seized up a week later, and John paid to have it overhauled. When he told me what had happened, we just laughed. I learned a lot about John from that experience.
With best wishes,
Arnold Howard Paragon Industries, L.P. – Better Designed Kilns 2011 South Town East Blvd., Mesquite, Texas 75149-1122 Voice: 972-288-7557 & 800-876-4328 / Fax: 972-222-0646 / firstname.lastname@example.org / www.paragonweb.com
PRIVACY NOTICE: Under no circumstance do we share or sell your email address.
Copyright 2010, by Paragon Industries, L.P.