Shown here is an older Amprobe ammeter. At one time that model was widely used at Paragon.
Interpreting a Kiln’s Amperage Reading
Recent Q&As: Digital kiln won’t shut off; repairing firebrick cracks; audible alarm signals
INTERPRETING A KILN’S AMPERAGE READING
The electrical data plate, which is mounted to the side of the switch box on most kilns, lists the kiln’s rated amperage. As the heating elements age, they pull fewer amps. Measuring the amps is one way to determine if the elements are beginning to age.
However, a low amperage reading does not always indicate worn out elements. The low reading could also be due to low voltage. To correctly interpret the amperage reading, first take a voltage reading of the circuit that powers the kiln.
Here is a useful formula:
Voltage tested with a voltmeter while the kiln is firing divided by the circuit’s rated voltage = ratio of loss
Ratio of loss multiplied by the kiln’s rated amps = expected amperage of a kiln fired at this new voltage
A 240-volt kiln is rated at 45 amps (10,800 watts). The 240-volt circuit gives a voltmeter reading of 240 volts. If the voltage reading drops to 235 while the kiln is firing, then
235 divided by 240 = 0.979
45 amps x 0.979 = 44 amps
44 amps is the normal amperage of a new 45-amp kiln fired on the 235-volt circuit.
44 amps x 235 volts = 10,340 watts. The normal wattage for this particular kiln on 240 volts is 10,800, but because of low voltage, the kiln will draw only 10,340 watts.
This example shows how low voltage affects the amperage reading. This is why a voltage reading should be taken before the amperage reading. Wattage is directly proportional to the maximum temperature that can be obtained; i.e., lower wattage results in a lower maximum temperature.
Here is a video that shows how to measure volts and amps:
Q. My kiln is not shutting off when it reaches cone 06. It is holding the temperature 1861 for hours and hours. After the controller shows me "cone 06" I see "5 20." How do I eliminate this?
A. Please check Program Review. A long hold time has been added to your cone 06 program. The 5 20 means the hold will continue for 5 hours and 20 minutes. To remove the hold time, reprogram the kiln for cone 06. When you see the Hold prompt, enter 0000.
Q. A very small piece of firebrick has broken out, and I am hoping I won't lose any more of it. Is there a liquid cement that I could pour on to seal the crack?
A. Generally, repair cement should not be used to cover cracks in firebricks, because the repair cement applied to the surface tends to break out later. This is due to the difference in expansion between the cement and the firebricks. The cement application must be thin.
Q. Which 12-key and 3-key controller error messages are accompanied by an audible alarm?
A. Sentry 12-key controller: ALAR, FTH, FTC, LTdE and HTdE
Sentry Xpress 3-key controller: ALAr, HTdE and CPLT (The Sentry Xpress does not have the FTH, FTC and LTdE alarms.)
"The greatest challenge to any thinker is stating the problem in a way that will allow a solution." -- Bertrand Russell
This Memorial Day I am thinking of one of my favorite poems, “In Flanders Fields,” by John McCrae. Its powerful images echo across a century of time.
We will be closed next Monday to observe the sacrifices of those who gave so very much. All of us at Paragon wish you a safe Memorial Day weekend.
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 / www.facebook.com/paragonkilns
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