Otl / Over Temperature Limit; Pf1 / Power Failure; Pf 2 / Power Failure; Pf 3 / Power Failure - Sentry Xpress 5.0 Instructions For Use Manual

OTL / Over Temperature Limit

The kiln has shut off because the temperature is hotter
than the one that was set in the
This problem takes only a moment to fix in the
tion.

PF1 / Power Failure

The power failed during a controlled cooling segment.
The kiln temperature was below the last active cooling seg-
ment temperature when the power came back on. The kiln
will not resume firing. See "Power Failures," next column.

PF 2 / Power Failure

The power failed, and the kiln temperature was below
212°F / 100°C when the power came back on. The kiln will
not resume firing.

PF 3 / Power Failure

The power failed, and the temperature dropped 72°F /
40°C while the power was off. The kiln will not resume fir-
ing. Check for a loose wire between the transformer and the
controller.

TC 2 / Thermocouple Failure

The thermocouple failed while the controller was at
.
[IDLE]
TCR / Thermocouple Leads Reversed
Check that the ther-
mocouple lead wires
are connected to the
correct terminals on the
back of the controller
and on the thermocou-
ple connection block.

Basic Power Failure Principles

The Sentry Xpress handles a power failure in two ways:
1
After a brief power failure, the controller continues
firing as before. It shows a normal temperature dis-
play alternating with
2
After an extended power failure,
will appear. The kiln will NOT resume firing.
[PF3]
The kiln will remain turned off after a power failure if
the temperature is below 212°F / 100°C when the power co-
mes back on or if the temperature drops 72°F / 40°C or
more while the power is off.
When the Sentry Xpress aborts a firing after a power
failure, the display will show the following:
option. See page 19.
[LIM]
[LIM]
.
[PF]
[PF 1] [PF 2]
Keep the kiln lid or door closed when the kiln is not in use.
[PF 1] [PF 2]
Total firing time before power failed
Temperature at the time of power failure
op-
Current kiln temperature
To resume firing, restart the program. The kiln will be-
gin firing again from its present temperature. For example,
the kiln reached 1000°F / 538°C when the power failed. The
temperature is 800°F / 426°C when you turn the kiln back
on. Firing will resume from 800°F / 426°C. You need not
cool the kiln to room temperature before starting a ceramic
firing over unless you decide to use new witness cones.
When you resume firing by pressing Start/Stop, the
controller will begin firing in the first segment that has a
higher target temperature than the current kiln tempera-
ture. However, if the power failed during a ramping down
(cooling) segment, the controller will resume firing from
the same cooling segment.
Using Ceramic Witness (Shelf) Cones
After an Extended Power Failure
Orton self-supporting pyrometric cones.
The firing was interrupted more than 100°F/56°C
from the cone temperature: Fire the ware again. It
is okay to use the same partially fired witness cones,
even if they cooled back down to room temperature. So
long as the cones did not heat to within 100°F/56°C of
maturity, they can be used again.
The firing was interrupted less than 100°F/56°C
from the cone temperature: Fire the ware again. If
the kiln shuts off within 100°F / 55°C of maturity, and the
temperature drops 50°F / 28°C or more after the kiln
shuts off, do not depend on the witness cones. Once they
cool 50°F / 28°C after they have been heated to within
or 100°F / 55°C of maturity, they will not bend properly.
This is because they form a hard shell.
or
[PF 3]
27