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Understanding the Printed Specs on a Relay

Check the coil voltage, which is printed on the side of the relay.


Understanding the Printed Specs on a Relay

Recent Q&As: Firing glass across two half shelves; reasons for digital temperature inaccuracy

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Before replacing the mechanical relay of a digital kiln, read the label printed on the side of the new relay to be sure you are installing the correct one. The label is confusing until you spend a little time studying it.

On the label, find the voltage of the relay coil, which is the electromagnet inside the relay. When the electromagnet receives a signal from the controller, terminals inside the relay come together. The terminals make a clicking noise and turn on the heating elements.

The voltage of the coil is printed on the relay near a symbol of the coil. (In the sample relays shown, the coil is symbolized by a rectangle with a diagonal line.) The coil in the top left relay is 12 volts DC, which is the most commonly used kiln relay. The coil in the bottom left relay is 240 volts AC. The coil in the relay on the right is 200 - 240 volts AC (for 208 volt kilns).

The 12 volt DC coil is used in relays that are turned on by a digital controller. The 240 volt AC coil is used for relays that are activated by an infinite control switch instead of a digital controller. The earlier Paragon GL-24ADTSD, which is a digital kiln with switches that adjust the top and side elements, uses both types of relays.

DC means direct current, which comes from the controller to the relays. The symbol for DC is a horizontal solid line over a broken line. AC is the current from the wall outlet and is symbolized by a wavy line.

The relay is rated for a level of current. The current rating of the relay does not mean it requires that much current to operate. The current rating is the maximum safe level that the relay can handle.



Q. How does one avoid the shelf seam line on the back of a glass piece when firing large pieces across two half shelves?

A. To avoid the line going through the middle of two half shelves butted together, lay the glass onto a sheet of 1/8" thick fiber paper placed over the shelf. You may be able to get multiple firings from the paper provided you work at tack fusing temperatures. The paper doesn't last long at full fuse.

Q. What receptacle (outlet) do you install on the kiln switch box for the Orton vent? Is the receptacle 120 volts in a 240 volt switch box?

A. We use both NEMA 5-15R (for 120 volt) and NEMA 6-15R (for 240 volt) receptacles, depending on the voltage of the kiln.

A 240 volt Orton Vent Master is used on a 240 volt kiln, so the 6-15R outlet is selected. A 120 volt Vent Master can be used in situations where a 120 volt supply is available, such as in a 120 volt kiln or a kiln with a step-down transformer added to the kiln’s switch box.

Q. What causes a kiln to become 500 degrees F. hotter than the thermocouple reading shown in the controller display window?

A. If the controller temperature reading is that far off, the problem is probably with the thermocouple installation. Check to see if the wire from the thermocouple to the controller is crimped or damaged. Also look for shorts between the thermocouple and the kiln case that might be grounding out the thermocouple signal. Make sure the thermocouple is not pushed back into the kiln wall.

A loose thermocouple connection probably would not be the issue. Loose connections cause random temperature readings or FAIL codes.



"There isn't a ruler, a yardstick or a measuring tape in the entire world long enough to compute the strength and capabilities inside you." -Paul Meyer



You are welcome to call us through Apple Facetime to trouble shoot kiln problems. Video trouble shooting has been very effective and a great time saver, because it is like having our customer service person right next to you. Aim your phone at the problem you are having with your kiln. For more information, please call or email Customer Service: 972-288-7557 /

Thank you,

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 / / /

PRIVACY NOTICE: Under no circumstance do we share or sell your email address.

Copyright 2017, by Paragon Industries, L.P.

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