Page
ST312A
User
Handbook
12
Operating Notes
If the ST312A is programmed to heat the kiln at a faster rate than the kiln
is capable of then the ST312A will turn on full power then wait until the
kiln temperature has risen to the correct temperature before proceeding to
the next ramp or soak segment.
Likewise if the ST312A is programmed to cool the kiln at a faster rate
than the kiln is capable of then the ST312A will apply zero power then
wait until the kiln has cooled to the correct temperature before proceeding
to the next ramp or soak segment.
Kiln too slow
Heating & Cooling Ramps
The ST312A is capable of controlled ramps for both heating and cooling.
If the soak temperature is set lower than t1 for example then ramp 2 will
automatically become a
negative
(cooling) ramp.
STOP key operation
If the START/STOP key is pressed during a firing then the firing will be
halted (not paused). Pressing the START/STOP key again will cause the
ST312 to restart the firing from the beginning. The ST312A will look at
the current kiln temperature and if this is greater than temperature t1 then
the ST312A will automatically
cool
from current temperature to t1 at
ramp rate 1. This may not be what is desired so the STOP key should
only be used to halt the firing in an emergency.
The program can be paused or program data can be changed while the
controller is firing (see page 14). This is a better option than using the
STOP key. The segment advance feature (see page 14) is however avail-
able to recover quickly from STOP key operation if required.
Memory
All programs & necessary data are remembered when the ST312A is
turned off. In the event of power failure during firing the ST312A will
automatically resume firing when power is returned (this feature can be
disabled: see installation handbook).
Firing
Delayed Start
The delayed start time period is set to
00
.
00
when the ST312A is turned on.
ST312A User Handbook
Page 9
Firing
To start a firing press the START/STOP key. The RUN lamp will light.
To stop the firing prematurely press the START/STOP key again.
.
20
°C
°C/hr
hr.min
If the left-hand decimal point is on then
the keyboard is locked & the ST312A
will not respond to the START/STOP
key. Press the
©
&
ª
keys together &
hold down for 5 seconds to unlock.
01
.
12
°C
°C/hr
hr.min
If a delayed start has been set then press-
ing the START/STOP key causes a time
delay to start. The time remaining is
shown on the display - this counts down
once per minute. The DELAYED
START lamp on the mimic panel will
light. The centre decimal point will flash
once per second.
20
.
°C
°C/hr
hr.min
If no delayed start has been set (00.00)
then pressing the START/STOP key
causes firing to commence immediately.
The RAMP 1 lamp on the mimic panel
will light. If kiln heating is required then
the right-hand decimal point on the dis-
play will light while heating power is
being applied to the kiln.
Information: The ST312A operates by calculating the amount of energy
required by the kiln every 30 seconds. If for example 40% of full energy is
required to maintain a particular ramp rate or a particular soak temperature
then the ST312A will apply heating power to the kiln for 12 seconds every 30
seconds. The right-hand decimal point in the display will light for 12 seconds
every 30 seconds. If the kiln has a contactor then a loud click will be heard both
when the decimal point lights up and when it goes out. If full heating power is
required then the decimal point will remain lit. If full cooling is required then
the decimal point will remain off.
Firing
Hint: it is good practice to check that the program is correct by pressing
the
¨
key & checking the program contents before pressing the START/
STOP key to start a firing.
