A glass artist recently asked about the error messages on the 12-key Sentry 2.0 digital controller. When he programmed a cooling rate that was faster than his kiln could cool, FTC appeared in the display window. A heating rate that is faster than the kiln can heat results in an FTH message. (FTC = Fail to Cool. FTH = Fail to Heat.)
Even though FTC or FTH appears, the kiln will continue its normal operation. The messages are to alert you that the kiln could not cool or heat as fast as you had programmed. But they will not shut off the kiln.
FTC and FTH are “temperature deviation” alarms. There are four deviation alarms:
FTH (Fail to Heat) The temperature is too low during a firing ramp. (During a firing ramp, the temperature goes up.)
FTC (Fail to Cool) The temperature is too high during a cooling ramp. (During a cooling ramp, the temperature goes down.)
HTDE (High Temperature Deviation) The temperature is too high during either a firing ramp or a hold. When HTDE appears, the controller will shut off the kiln. This is a safety measure. HTDE is the only temperature deviation alarm that will shut off the kiln.
LTDE (Low Temperature Deviation) The temperature is too low during a cooling ramp or during a hold.
All four deviation alarms are turned off when you enter a cooling or heating rate of 9999 in Ramp-Hold mode. (They turn off only during a segment that has a 9999 rate.) Remember that the HTDE alarm (high temperature deviation) will also remain off. This alarm shuts off the kiln when temperature rises too much during a heating ramp or hold.
Some people worry when FTH, FTC, or LTDE appears. They wonder if something is wrong with the kiln. Here are the methods to set the deviation temperature so that the alarm messages do not appear during routine firings:
1) Test your kiln to find its fastest firing rate and its slowest cooling rate. Then program the controller using rates within the range of the kiln’s heating/cooling capacity. If your fastest heating rate is 600° per hour, enter a rate no faster than 600°.
2) Set the deviation temperature to a higher number in the Sentry’s Options. The higher the number, the less likely that an alarm message will appear.
3) Set the deviation temperature to 0 in the Sentry’s Options. Note, however, that this turns off the HTDE alarm, which shuts the kiln off when the temperature is higher than the deviation setting. We do not recommend a 0 setting.
To adjust the Sentry 2.0 temperature deviation setting:
1) From IDLE, press OPTIONS repeatedly until TEDE appears.
2) Press ENTER. Change the deviation temperature. Press ENTER. Press STOP to return to IDLE.